9. Rules list

9.1. Introduction

9.2. $HTTP_RAW_POST_DATA Usage

$HTTP_RAW_POST_DATA is deprecated, and should be replaced by php://input.

$HTTP_RAW_POST_DATA is deprecated since PHP 5.6.

It is possible to prepare code to this lack of feature by setting always_populate_raw_post_data to -1.

<?php

// PHP 5.5 and older
$postdata = $HTTP_RAW_POST_DATA;

// PHP 5.6 and more recent
$postdata = file_get_contents(php://input);

?>

See also $HTTP_RAW_POST_DATA variable.

9.2.1. Suggestions

  • Use php://input with fopen() instead.
Short name Php/RawPostDataUsage
Rulesets CompatibilityPHP56
Severity Major
Time To Fix Slow (1 hour)

9.3. $php_errormsg Usage

$php_errormsg is removed since PHP 8.0. $php_errormsg tracks the last error message, with the directive track_errors. All was removed in PHP 8.0, and shall be replaced with error_get_last().

<?php

function foo() {
    global $php_errormsg;

    echo 'Last error: '.$php_errormsg;

    echo 'Also, last error: '.error_get_last();
}

?>

9.3.1. Suggestions

  • Use error_get_last() instead.
Short name Php/PhpErrorMsgUsage
Rulesets CompatibilityPHP80
Php Version 8.0-
Severity Minor
Time To Fix Quick (30 mins)

9.4. $this Belongs To Classes Or Traits

$this variable represents the current object, inside a class or trait scope.

It is a pseudo-variable, and should be used within class’s or trait’s methods and not outside. It should also not be used in static methods.

PHP 7.1 is stricter and check for $this at several situations. Some are found by static analysis, some are dynamic analysis.

<?php

// as an argument
function foo($this) {
    // Using global
    global $this;
    // Using static (not a property)
    static $this;

    // Can't unset it
    unset($this);

    try {
        // inside a foreach
        foreach($a as $this) {  }
        foreach($a as $this => $b) {  }
        foreach($a as $b => $this) {  }
    } catch (Exception $this) {
        // inside a catch
    }

    // with Variable Variable
    $a = this;
    $$a = 42;
}

class foo {
    function bar() {
        // Using references
        $a =& $this;
        $a = 42;

        // Using extract(), parse_str() or similar functions
        extract([this => 42]);  // throw new Error(Cannot re-assign $this)
        var_dump($this);
    }

    static function __call($name, $args) {
        // Using __call
        var_dump($this); // prints object(C)#1 (0) {}, php-7.0 printed NULL
        $this->test();   // prints ops
    }

}
?>

9.4.1. Suggestions

  • Do not use $this as a variable name, except for the current object, in a class, trait or closure.
Short name Classes/ThisIsForClasses
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)
Examples OpenEMR

9.5. $this Is Not An Array

$this variable represents the current object and it is not an array.

This is unless the class (or its parents) has the ArrayAccess interface, or extends ArrayObject or SimpleXMLElement.

<?php

// $this is an array
class Foo extends ArrayAccess {
    function bar() {
        ++$this[3];
    }
}

// $this is not an array
class Foo2 {
    function bar() {
        ++$this[3];
    }
}

?>

See also ArrayAccess, ArrayObject and The Basics.

9.5.1. Suggestions

  • Extends ArrayObject, or a class that extends it, to use $this as an array too.
  • Implements ArrayAccess to use $this as an array too.
  • Use a property in the current class to store the data, instead of $this directly.
Short name Classes/ThisIsNotAnArray
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.6. $this Is Not For Static Methods

Static methods shouldn’t use $this variable.

$this variable represents an object, the current object. It is not compatible with a static method, which may operate without any object.

While executing a static method, $this is actually set to NULL.

<?php

class foo {
    static $staticProperty = 1;

    // Static methods should use static properties
    static public function count() {
        return self::$staticProperty++;
    }

    // Static methods can't use $this
    static public function bar() {
        return $this->a;   // No $this usage in a static method
    }
}

?>

See also Static Keyword <https://www.php.net/manual/en/language.oop5.`static.php>`_.

9.6.1. Suggestions

  • Remove the static keyword on the method, and update all calls to this method to use $this
  • Remove the usage of $this in the method, replacing it with static properties
  • Make $this an argument (and change its name) : then, make the method a function
Short name Classes/ThisIsNotForStatic
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-static-this

9.7. ** For Exponent

The operator ** calculates exponents, also known as power.

Use it instead of the slower function pow(). This operator was introduced in PHP 5.6.

<?php
    $cube = pow(2, 3); // 8

    $cubeInPHP56 = 2 ** 3; // 8
?>

Be aware the the ‘-‘ operator has lower priority than the ** operator : this leads to the following confusing result.

<?php
    echo -3 ** 2;
    // displays -9, instead of 9
?>

This is due to the parser that processes separately - and the following number. Since ** has priority, the power operation happens first.

Being an operator, ** is faster than pow(). This is a microoptimisation.

See also Arithmetic Operators.

9.7.1. Suggestions

  • Use the ** operator
  • For powers of 2, use the bitshift operators
  • For literal powers of 2, consider using the 0xFFFFFFFFF syntax.
Short name Php/NewExponent
Rulesets Suggestions, php-cs-fixable
Php Version With PHP 5.6 and more recent
Severity Minor
Time To Fix Quick (30 mins)
Precision Very high
Examples Traq, TeamPass

9.8. ::class

PHP has a special class constant to hold the name of the class : class keyword. It represents the class name that is used in the left part of the operator.

Using \:\:class is safer than relying on a string. It does adapt if the class’s name or its namespace is changed’. It is also faster, though it is a micro-optimisation.

It is introduced in PHP 5.5.

<?php

use A\B\C as UsedName;

class foo {
    public function bar( ) {
        echo ClassName::class;
        echo UsedName::class;
    }
}

$f = new Foo( );
$f->bar( );
// displays ClassName
// displays A\B\C

?>

Be aware that \:\:class is a replacement for __CLASS__ magic constant.

See also Class Constant.

9.8.1. Suggestions

  • Use ::class whenever possible. That exclude any dynamic call.
Short name Php/StaticclassUsage
Rulesets CompatibilityPHP53, CompatibilityPHP54
Php Version With PHP 5.5 and more recent
Severity Major
Time To Fix Slow (1 hour)
Precision Very high

9.9. @ Operator

@ is the ‘no scream’ operator : it suppresses error output.

<?php

// Set x with incoming value, or else null.
$x = @$_GET['x'];

?>

This operator is actually very slow : it will process the error all the way up, and finally decide not to display it. It is often faster to check the conditions first, then run the method without @.

You may also set display_error to 0 in the php.ini : this will avoid user’s error display, but will keep the error in the PHP logs, for later processing.

The only situation where @ is useful is when a native PHP function displays errors messages when error happens and there is no way to check it from the code.

This is the case with fopen(), stream_socket_server(), token_get_all().

See also Error Control Operators and Five reasons why the shut-op operator should be avoided.

9.9.1. Suggestions

  • Remove the @ operator by default
Name Default Type Description
authorizedFunctions noscream_functions.json data Functions that are authorized to sports a @.
Short name Structures/Noscream
Rulesets Analyze, Performances, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Precision Very high
ClearPHP no-noscream
Examples Phinx, PhpIPAM

9.10. Abstract Away

Avoid using PHP native functions that produce data direcly in the code. For example, date() or random_int(). They should be abstracted away in a method, that will be replaced later for testing purposes, or even debugging.

To abstract such calls, place them in a method, and add an interface to this method. Then, create and use those objects.

<?php

// abstracted away date
$today = new MyDate();
echo 'Date : '.$today->date('r');

// hard coded date of today : it changes all the time.
echo 'Date : '.date('r');

interface MyCalendar{
    function date($format) : string ;
}

class MyDate implements MyCalendar {
    function date($format) : string { return date('r'); }
}

// Valid implementation, reserved for testing purpose
// This prevents from waiting 4 years for a test.
class MyDateForTest implements MyCalendar {
    function date($format) : string { return date('r', strtotime('2016-02-29 12:00:00')); }
}

?>

This analysis targets two API for abstraction : time and random values. Time and date related functions may be replaced by Carbon, Clock, Chronos. Random values may be replaced with RandomLib or a custome interface.

See also Being in control of time in PHP and How to test non-deterministic code.

9.10.1. Suggestions

  • Abstract away the calls to native PHP functions, and upgrade the unit tests
Name Default Type Description
abstractableCalls   ini_hash Functions that shouldn’t be called directly, unless in a method.
abstractableClasses   ini_hash Classes that shouldn’t be instantiated directly, unless in a method.
Short name Patterns/AbstractAway
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.11. Abstract Or Implements

A class must implements all abstract methods of it parent, or be abstract too.

While PHP lints this code, it won’t execute it and stop with a Fatal Error : Class BA contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (A\:\:aFoo).

<?php

abstract class Foo {
    abstract function FooBar();
}

// This is in another file : php -l would detect it right away

class FooFoo extends Foo {
    // The method is not defined.
    // The class must be abstract, just like Foo
}

?>

See also Class Abstraction.

9.11.1. Suggestions

  • Implements all the abstract methods of the class
  • Make the class abstract
Short name Classes/AbstractOrImplements
Rulesets Analyze, LintButWontExec
Severity Major
Time To Fix Quick (30 mins)
Examples Zurmo

9.12. Abstract Static Methods

Methods cannot be both abstract and static. Static methods belong to a class, and will not be overridden by the child class. For normal methods, PHP will start at the object level, then go up the hierarchy to find the method. With static, it is necessary to mention the name, or use Late Static Binding, with self or static. Hence, it is useless to have an abstract static method : it should be a static method.

A child class is able to declare a method with the same name than a static method in the parent, but those two methods will stay independent.

This is not the case anymore in PHP 7.0+.

<?php

abstract class foo {
    // This is not possible
    static abstract function bar() ;
}

?>

See also Why does PHP 5.2+ disallow abstract `static class methods? <https://stackoverflow.com/questions/999066/why-does-php-5-2-disallow-abstract-static-class-methods>`_.

9.12.1. Suggestions

  • Remove abstract keyword from the method
  • Remove static keyword from the method
  • Remove the method
Short name Classes/AbstractStatic
Rulesets Analyze
Php Version With PHP 7.0 and older
Severity Minor
Time To Fix Quick (30 mins)

9.13. Access Protected Structures

It is not allowed to access protected properties or methods from outside the class or its relatives.

<?php

class foo {
    protected $bar = 1;
}

$foo = new Foo();
$foo->bar = 2;

?>

See also Visibility and Understanding The Concept Of Visibility In Object Oriented PHP.

9.13.1. Suggestions

  • Change ‘protected’ to ‘public’ to relax the constraint
  • Add a getter method to reach the target value
  • Remove the access to the protected value and find it another way
Short name Classes/AccessProtected
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.14. Accessing Private

List of calls to private properties/methods that will compile but yield some fatal error upon execution.

<?php

class a {
    private $a;
}

class b extends a {
    function c() {
        $this->a;
    }
}

?>
Short name Classes/AccessPrivate
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.15. Add Default Value

Parameter in methods definition may receive a default value. This allows the called method to set a value when the parameter is omitted.

<?php

function foo($i) {
    if (!is_integer($i)) {
        $i = 0;
    }
}

?>

See also Function arguments.

9.15.1. Suggestions

  • Add a default value for parameters
Short name Functions/AddDefaultValue
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)
Examples Zurmo, Typo3

9.16. Adding Zero

Adding 0 is useless, as 0 is the neutral element for addition. Besides, when one of the argument is an integer, PHP triggers a cast to integer.

It is recommended to make the cast explicit with (int).

<?php

// Explicit cast
$a = (int) foo();

// Useless addition
$a = foo() + 0;
$a = 0 + foo();

// Also works with minus
$b = 0 - $c; // drop the 0, but keep the minus
$b = $c - 0; // drop the 0 and the minus

$a += 0;
$a -= 0;

?>

Adding zero is also reported when the zero is a defined constants.

If it is used to type cast a value to integer, then casting with (int) is clearer.

9.16.1. Suggestions

  • Remove the +/- 0, may be the whole assignation
  • Use an explicit type casting operator (int)
Short name Structures/AddZero
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP no-useless-math
Examples Thelia, OpenEMR

9.17. Aliases Usage

PHP manual recommends to avoid function aliases.

Some functions have several names, and both may be used the same way. However, one of the names is the main name, and the others are aliases. Aliases may be removed or change or dropped in the future. Even if this is not forecast, it is good practice to use the main name, instead of the aliases.

<?php

// official way to count an array
$n = count($array);

// official way to count an array
$n = sizeof($array);

?>

Aliases are compiled in PHP, and do not provide any performances over the normal function.

Aliases are more likely to be removed later, but they have been around for a long time.

See documentation : List of function aliases.

9.17.1. Suggestions

  • Always use PHP recommended functions
Short name Functions/AliasesUsage
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
ClearPHP no-aliases
Examples Cleverstyle, phpMyAdmin

9.18. All Uppercase Variables

Usually, global variables are all in uppercase, so as to differentiate them easily. Though, this is not always the case, with examples like $argc, $argv or $http_response_header.

When using custom variables, try to use lowercase $variables, $camelCase, $sturdyCase or $snake_case.

<?php

// PHP super global, also identified by the initial _
$localVariable = $_POST;

// PHP globals
$localVariable = $GLOBALS['HTTPS'];

?>

See also Predefined Variables.

Short name Variables/VariableUppercase
Rulesets Coding Conventions
Severity Minor
Time To Fix Slow (1 hour)

9.19. Already Parents Interface

The same interface is implemented by a class and one of its children.

That way, the child doesn’t need to implement the interface, nor define its methods to be an instance of the interface.

<?php

interface i {
    function i();
}

class A implements i {
    function i() {
        return __METHOD__;
    }
}

// This implements is useless.
class AB extends A implements i {
    // No definition for function i()
}

// Implements i is understated
class AB extends A {
    // redefinition of the i method
    function i() {
        return __METHOD__.' ';
    }
}

$x = new AB;
var_dump($x instanceof i);
// true

$x = new AC;
var_dump($x instanceof i);
// true

?>

9.19.1. Suggestions

  • Keep the implements call in the class that do implements the methods. Remove it from the children classes.
Short name Interfaces/AlreadyParentsInterface
Rulesets Analyze, Suggestions
Severity Minor
Time To Fix Instant (5 mins)
Examples WordPress, Thelia

9.20. Already Parents Trait

Trait is already used a parent’s class or trait. There is no use to include it a second time.

<?php

trait ta {
    use tb;
}

trait t1 {
    use ta;
    use tb; // also used by ta
}

class b {
    use t1; // also required by class c
    use ta; // also required by trait t1
}

class c extends b {
    use t1;
}

?>

See also Traits.

9.20.1. Suggestions

  • Eliminate one of the trait request
Short name Traits/AlreadyParentsTrait
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.21. Altering Foreach Without Reference

Foreach() loop that should use a reference.

When using a foreach loop that modifies the original source, it is recommended to use referenced variables, rather than access the original value with $source[$index].

Using references is then must faster, and easier to read.

<?php

// Using references in foreach
foreach($source as $key => &$value) {
    $value = newValue($value, $key);
}

// Avoid foreach : use array_map
$source = array_walk($source, 'newValue');
    // Here, $key MUST be the second argument or newValue

// Slow version to update the array
foreach($source as $key => &$value) {
    $source[$key] = newValue($value, $key);
}
?>

You may also use array_walk() or array_map() (when $key is not used) to avoid the use of foreach.

See also foreach.

9.21.1. Suggestions

  • Add the reference on the modified blind variable, and avoid accessing the source array
Short name Structures/AlteringForeachWithoutReference
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
ClearPHP use-reference-to-alter-in-foreach
Examples Contao, WordPress

9.22. Alternative Syntax Consistence

PHP allows for two syntax : the alternative syntax, and the classic syntax.

The classic syntax is almost always used. When used, the alternative syntax is used in templates.

This analysis reports files that are using both syntax at the same time. This is confusing.

<?php

// Mixing both syntax is confusing.
foreach($array as $item) :
    if ($item > 1) {
        print $item elements\n;
    } else {
        print $item element\n;
    }
endforeach;

?>
Short name Structures/AlternativeConsistenceByFile
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.23. Always Anchor Regex

Unanchored regex finds the requested pattern, and leaves room for malicious content.

Without ^ and $, the regex searches for any pattern that satisfies the criteria, leaving any unused part of the string available for arbitrary content. It is recommended to use both anchor

<?php

$birthday = getSomeDate($_GET);

// Permissive version : $birthday = '1970-01-01<script>xss();</script>';
if (!preg_match('/\d{4}-\d{2}-\d{2}/', $birthday) {
    error('Wrong data format for your birthday!');
}

// Restrictive version : $birthday = '1970-01-01';
if (!preg_match('/^\d{4}-\d{2}-\d{2}$/', $birthday) {
    error('Wrong data format for your birthday!');
}

echo 'Your birthday is on '.$birthday;

?>

Note that $ may be a line ending, still leaving room after it for injection.

<?php

$birthday = '1970-01-01'.PHP_EOL.'<script>xss();</script>';

?>

This analysis reports false positive when the regex is used to search a pattern in a much larger string. Check if this rule doesn’t apply, though.

See also CWE-625: Permissive Regular Expression.

9.23.1. Suggestions

  • Add an anchor to the beginning and ending of the string
Short name Security/AnchorRegex
Rulesets Security
Severity Major
Time To Fix Instant (5 mins)

9.24. Always Positive Comparison

Some PHP native functions, such as count(), strlen(), or abs() only returns positive or null values.

When comparing them to 0, the following expressions are always true and should be avoided.

<?php

$a = [1, 2, 3];

var_dump(count($a) >= 0);
var_dump(count($a) < 0);

?>

9.24.1. Suggestions

  • Compare count() to non-zero values
  • Use empty()
Short name Structures/NeverNegative
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Instant (5 mins)
Examples Magento

9.25. Always Use Function With array_key_exists()

array_key_exists() has been granted a special VM opcode, and is much faster. This applies to PHP 7.4 and more recent.

It requires that array_key_exists() is statically resolved, either with an initial \, or a use function expression. This doesn’t affect the global namespace.

<?php

namespace my/name/space;

// do not forget the 'function' keyword, or it will apply to classes.
use function array_key_exists as foo; // the alias is not necessary, and may be omitted.

// array_key_exists is aliased to foo :
$c = foo($a, $b);

// This call requires a fallback to global, and will be slow.
$c = array_key_exists($a, $b);

?>

This analysis is related to Php/ShouldUseFunction, and is a special case, that only concerns array_key_exists().

See also Add array_key_exists to the list of specialy compiled functions.

9.25.1. Suggestions

  • Use the use command for arrray_key_exists(), at the beginning of the script
  • Use an initial before array_key_exists()
  • Remove the namespace
Short name Performances/Php74ArrayKeyExists
Rulesets Performances
Php Version 7.4+
Severity Minor
Time To Fix Quick (30 mins)

9.26. Ambiguous Array Index

Indexes should not be defined with different types than int or string.

Array indices only accept integers and strings, so any other type of literal is reported. In fact, null is turned into an empty string, booleans are turned into an integer, and real numbers are truncated (not rounded).

<?php

$x = [ 1  => 1,
      '1' => 2,
      1.0 => 3,
      true => 4];
// $x only contains one element : 1 => 4

// Still wrong, immediate typecast to 1
$x[1.0]  = 5;
$x[true] = 6;

?>

They are indeed distinct, but may lead to confusion.

See also array.

9.26.1. Suggestions

  • Only use string or integer as key for an array.
  • Use transtyping operator (string) and (int) to make sure of the type
Short name Arrays/AmbiguousKeys
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples PrestaShop, Mautic

9.27. Ambiguous Static

Methods or properties with the same name, are defined static in one class, and not static in another. This is error prone, as it requires a good knowledge of the code to make it static or not.

Try to keep the methods simple and unique. Consider renaming the methods and properties to distinguish them easily. A method and a static method have probably different responsibilities.

<?php

class a {
    function mixedStaticMethod() {}
}

class b {
    static function mixedStaticMethod() {}
}

/... a lot more code later .../

$c->mixedStaticMethod();
// or
$c::mixedStaticMethod();

?>
Short name Classes/AmbiguousStatic
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)

9.28. Ambiguous Visibilities

The properties have the same name, but have different visibilities, across different classes.

While it is legit to have a property with the same name in different classes, it may easily lead to confusion. As soon as the context is need to understand if the property is accessible or not, the readability suffers.

It is recommended to handle the same properties in the same way across classes, even when the classes are not related.

<?php

class person {
    public $name;
    private $address;
}

class gangster {
    private $name;
    public $nickname;
    private $address;
}

$someone = Human::load(123);
echo 'Hello, '.$someone->name;

?>

9.28.1. Suggestions

  • Sync visibilities for both properties, in the different classes
  • Use different names for properties with different usages
Short name Classes/AmbiguousVisibilities
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples Typo3

9.29. Anonymous Classes

Anonymous classes.

<?php

// Anonymous class, available since PHP 7.0
$object = new class { function __construct() { echo __METHOD__; } };

?>
Short name Classes/Anonymous
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and more recent
Severity Major
Time To Fix Slow (1 hour)

9.30. Argument Should Be Typehinted

When a method expects objects as argument, those arguments should be typehinted. This way, it provides early warning that a wrong object is being sent to the method.

The analyzer will detect situations where a class, or the keywords ‘array’ or ‘callable’.

<?php

// What are the possible classes that have a 'foo' method?
function foo($bar) {
    return $bar->foo();
}

?>

Closure arguments are omitted.

See also Type declarations.

9.30.1. Suggestions

  • Add the typehint to the function arguments
Short name Functions/ShouldBeTypehinted
Rulesets Typechecks
Severity Minor
Time To Fix Slow (1 hour)
ClearPHP always-typehint
Examples Dolphin, Mautic

9.31. Array_Fill() With Objects

array_fill() fills an array with identical objects, not copies nor clones. This means that all the filled objects are a reference to the same object. Changing one of them will change any of them.

Make sure this is the intended effect in the code.

<?php

$x = new StdClass();
$array = array_fill(0, 10, $x);

$array[3]->y = Set in object #3;

// displays Set in object #3;
echo $array[5]->y;

?>

This applies to array_pad() too. It doesn’t apply to array_fill_keys(), as objects will be cast to a string before usage in this case.

9.31.1. Suggestions

  • Use a loop to fill in the array with cloned() objects.
Short name Structures/ArrayFillWithObjects
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.32. Array_merge Needs Array Of Arrays

When collecting data to feed array_merge(), use an array of array as default value. `array(`array()) <https://www.php.net/array>`_` is the neutral value for array_merge();

This analysis also reports when the used types are not an array : array_merge() does not accept scalar values, but only arrays.

<?php

// safe default value
$a = array(array());

// when $list is empty, it is
foreach($list as $l) {
    $a[] = $l;
}
$b = array_merge($a);

?>

Since PHP 7.4, it is possible to call array_merge() without an argument : this means the default value may an empty array. This array shall not contain scalar values.

See also array_merge.

9.32.1. Suggestions

  • Use `array(array())` or `[[]]` as default value for array_merge()
  • Remove any non-array value from the values in the default array
Short name Structures/ArrayMergeArrayArray
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.33. Assert Function Is Reserved

Avoid defining an assert function in namespaces.

While they work fine when the assertions are active (zend.assertions=1), calls to unqualified assert are optimized away when assertions are not active.

Since PHP 7.3, a fatal error is emitted : Defining a custom `assert() <https://www.php.net/assert>`_ function is deprecated, as the function has special semantics.

<?php
//      Run this with zend.assertions=1 and
// Then run this with zend.assertions=0

namespace Test {
    function assert() {
        global $foo;

        $foo = true;
    }
}

namespace Test {
    assert();

    var_dump(isset($foo));
}

?>

See also assert and User-defined assert function is optimized away with zend.assertions=-1.

9.33.1. Suggestions

  • Rename the custom function with another name
Short name Php/AssertFunctionIsReserved
Rulesets Analyze, CompatibilityPHP73
Severity Critical
Time To Fix Slow (1 hour)

9.34. Assign And Compare

Assignation has a lower precedence than comparison. As such, the assignation always happens after the comparison. This leads to the comparison being stored in the variable, and not the value being compared.

<?php

if ($id = strpos($string, $needle) !== false) {
    // $id now contains a boolean (true or false), but not the position of the $needle.
}

// probably valid comparison, as $found will end up being a boolean
if ($found = strpos($string, $needle) === false) {
    doSomething();
}

// always valid comparison, with parenthesis
if (($id = strpos($string, $needle)) !== false) {
    // $id now contains a boolean (true or false), but not the position of the $needle.
}

// Being a lone instruction, this is always valid : there is no double usage with if condition
$isFound = strpos($string, $needle) !== false;


?>

See also Operator Precedence.

9.34.1. Suggestions

  • Use parenthesis
  • Separate assignation and comparison
  • Drop assignation or comparison
Short name Structures/AssigneAndCompare
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.35. Assign Default To Properties

Properties may be assigned default values at declaration time. Such values may be later modified, if needed.

<?php

class foo {
    private $propertyWithDefault = 1;
    private $propertyWithoutDefault;
    private $propertyThatCantHaveDefault;

    public function __construct() {
        // Skip this extra line, and give the default value above
        $this->propertyWithoutDefault = 1;

        // Static expressions are available to set up simple computation at definition time.
        $this->propertyWithoutDefault = OtherClass::CONSTANT + 1;

        // Arrays, just like scalars, may be set at definition time
        $this->propertyWithoutDefault = [1,2,3];

        // Objects or resources can't be made default. That is OK.
        $this->propertyThatCantHaveDefault = fopen('/path/to/file.txt');
        $this->propertyThatCantHaveDefault = new Fileinfo();
    }
}

?>

Default values will save some instructions in the constructor, and makes the value obvious in the code.

9.35.1. Suggestions

  • Add a default value whenever possible. This is easy for scalars, and array()
Short name Classes/MakeDefault
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP use-properties-default-values
Examples LiveZilla, phpMyAdmin

9.36. Assign With And

The lettered logical operators yield to assignation. It may collect less information than expected.

It is recommended to use the &&, ^ and || operators, instead of and, or and xor, to prevent confusion.

<?php

// The expected behavior is
// The following are equivalent
 $a =  $b  && $c;
 $a = ($b && $c);

// The unexpected behavior is
// The following are equivalent
 $a = $b  and $c;
($a = $b) and $c;

?>

See also Operator Precedence.

9.36.1. Suggestions

  • Always use symbol && rather than letter and
  • To be safe, add parenthesis to enforce priorities
Short name Php/AssignAnd
Rulesets Analyze, CI-checks
Severity Critical
Time To Fix Quick (30 mins)
Examples xataface

9.37. Assigned Twice

The same variable is assigned twice in the same function.

While this is possible and quite common, it is also a good practice to avoid changing a value from one literal to another. It is far better to assign the new value to

Incremental changes to a variables are not reported here.

<?php

function foo() {
    // incremental changes of $a;
    $a = 'a';
    $a++;
    $a = uppercase($a);

    $b = 1;
    $c = bar($b);
    // B changed its purpose. Why not call it $d?
    $b = array(1,2,3);

    // This is some forgotten debug
    $e = $config->getSomeList();
    $e = array('OneElement');
}

?>
Short name Variables/AssignedTwiceOrMore
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.38. Assumptions

Assumptions in the code, that leads to possible bugs.

Some conditions may be very weak, and lead to errors. For example, the code below checks that the variable $a is not null, then uses it as an array. There is no relationship between ‘not null’ and ‘being an array’, so this is an assumption.

<?php

// Assumption : if $a is not null, then it is an array. This is not always the case.
function foo($a) {
    if ($a !== null) {
        echo $a['name'];
    }
}

// Assumption : if $a is not null, then it is an array. Here, the typehint will ensure that it is the case.
// Although, a more readable test is is_array()
function foo(?array $a) {
    if ($a !== null) {
        echo $a['name'];
    }
}

?>

See also From assumptions to assertions.

9.38.1. Suggestions

Short name Php/Assumptions
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.39. Autoappend

Appending a variable to itself leads to enormous usage of memory.

<?php

// Always append a value to a distinct variable
foreach($a as $b) {
    $c[] = $b;
}

// This copies the array to itself, and double the size each loop
foreach($a as $b) {
    $c[] = $c;
}
?>

9.39.1. Suggestions

  • Change the variable in the append, on the left
  • Change the variable in the append, on the right
Short name Performances/Autoappend
Rulesets Performances
Severity Minor
Time To Fix Quick (30 mins)

9.40. Avoid Concat In Loop

Concatenations inside a loop generate a lot of temporary variables. They are accumulated and tend to raise the memory usage, leading to slower performances.

It is recommended to store the values in an array, and then use implode() on that array to make the concatenation at once. The effect is positive when the source array has at least 50 elements.

<?php

// Concatenation in one operation
$tmp = array();
foreach(data_source() as $data) {
    $tmp[] = $data;
}
$final = implode('', $tmp);

// Concatenation in many operations
foreach(data_source() as $data) {
    $final .= $data;
}

?>

The same doesn’t apply to addition and multiplication, with array_sum() and array_multiply(), as those operations work on the current memory allocation, and don’t need to allocate new memory at each step.

See also PHP 7 performance improvements (3/5): Encapsed strings optimization.

9.40.1. Suggestions

  • Collect all pieces in an array, then implode() the array in one call.
Short name Performances/NoConcatInLoop
Rulesets Performances, Top10
Severity Major
Time To Fix Slow (1 hour)
Examples SuiteCrm, ThinkPHP

9.41. Avoid Large Array Assignation

Avoid setting large arrays to local variables. This is done every time the function is called.

There are different ways to avoid this : inject the array, build the array once. Using an constant or even a global variable is faster.

The effect on small arrays (less than 10 elements) is not significant. Arrays with 10 elements or more are reported here. The effect is also more important on functions that are called often, or within loops.

<?php

// with constants, for functions
const ARRAY = array(1,2,3,4,5,6,7,8,9,10,11);
function foo() {
    $array = ARRAY;
    //more code
}

// with class constants, for methods
class x {
    const ARRAY = array(1,2,3,4,5,6,7,8,9,10,11);
    function foo() {
        $array = self::ARRAY;
        //more code
    }
}

// with properties, for methods
class x {
    private $array = array(1,2,3,4,5,6,7,8,9,10,11);

    function foo() {
        $array = $this->array;
        //more code
    }
}

// injection, leveraging default values
function foo($array = array(1,2,3,4,5,6,7,8,9,10,11)) {
    //more code
}

// local cache with static
function foo() {
    static $array;
    if ($array === null) {
        $array = array(1,2,3,4,5,6,7,8,9,10,11);
    }

    //more code
}

// Avoid creating the same array all the time in a function
class x {
    function foo() {
        // assign to non local variable is OK.
        // Here, to a property, though it may be better in a __construct or as default values
        $this->s = array(1,2,3,4,5,6,7,8,9,10,11);

        // This is wasting resources, as it is done each time.
        $array = array(1,2,3,4,5,6,7,8,9,10,11);
    }
}

?>
Short name Structures/NoAssignationInFunction
Rulesets Performances
Severity Minor
Time To Fix Slow (1 hour)

9.42. Avoid Optional Properties

Avoid optional properties, to prevent littering the code with existence checks.

When a property has to be checked once for existence, it is safer to check it each time. This leads to a decrease in readability and a lot of checks added to the code.

Either make sure the property is set with an actual object rather than with null, or use a null object. A null object offers the same interface than the expected object, but does nothing. It allows calling its methods, without running into a Fatal error, nor testing it.

<?php

// Example is courtesy 'The Coding Machine' : it has been adapted from its original form. See link below.

class MyMailer {
    private $logger;

    public function __construct(LoggerInterface $logger = null) {
        $this->logger = $logger;
    }

    private function sendMail(Mail $mail) {
        // Since $this->logger may be null, it must be tested anytime it is used.
        if ($this->logger) {
            $this->logger->info('Mail successfully sent.');
        }
    }
}

?>

See also Avoid optional services as much as possible, The Null Object Pattern – Polymorphism in Domain Models, and Practical PHP Refactoring: Introduce Null Object.

9.42.1. Suggestions

  • Use a null object to fill any missing value
  • Make sure the property is set at constructor time
Short name Classes/AvoidOptionalProperties
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)
Examples ChurchCRM, Dolibarr

9.43. Avoid Parenthesis

Avoid Parenthesis for language construct. Languages constructs are a few PHP native elements, that looks like functions but are not.

Among other distinction, those elements cannot be directly used as variable function call, and they may be used with or without parenthesis.

<?php

// normal usage of include
include 'file.php';

// This looks like a function and is not
include('file2.php');

?>

The usage of parenthesis actually give some feeling of comfort, it won’t prevent PHP from combining those argument with any later operators, leading to unexpected results.

Even if most of the time, usage of parenthesis is legit, it is recommended to avoid them.

Short name Structures/PrintWithoutParenthesis
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.44. Avoid Real

PHP has two float data type : real and double. real is rarely used, and might be deprecated in PHP 7.4.

To prepare code, avoid using is_real() and the (real) typecast.

<?php

// safe way to check for float
if (!is_float($a)) {
    $a = (float) $a;
}

// Avoid doing that
if (!is_real($a)) {
    $a = (real) $a;
}

?>

See also PHP RFC: Deprecations for PHP 7.4.

9.44.1. Suggestions

  • Replace is_real() by is_float()
  • Replace (real) by (float)
Short name Php/AvoidReal
Rulesets Suggestions, Top10
Severity Minor
Time To Fix Quick (30 mins)

9.45. Avoid Self In Interface

Self and Parent are tricky when used in an interface.

self refers to the current interface or its extended parents : as long as the constant is defined in the interface family, this is valid. On the other hand, when self refers to the current class, the resolution of names will happen at execution time, leading to confusing results.

parent has the same behavior than self, except that it doesn’t accept to be used inside an interface, as it will yield an error. This is one of those error that lint but won’t execute in certain conditions.

Static can’t be used in an interface, as it needs to be resolved at call time anyway.

<?php

interface i extends ii {
    // This 'self' is valid : it refers to the interface i
    public const I = self::I2 + 2;

    // This 'self' is also valid, as it refers to interface ii, which is a part of interface i
    public const I2 = self::IP + 4;

    // This makes interface i dependant on the host class
    public const I3 = parent::A;
}

?>

See also Scope Resolution Operator (::).

9.45.1. Suggestions

  • Use a fully qualified namespace instead of self
  • Use a locally defined constant, so self is a valid reference
Short name Interfaces/AvoidSelfInInterface
Rulesets ClassReview
Severity Critical
Time To Fix Slow (1 hour)

9.46. Avoid Substr() One

Use array notation $string[$position] to reach a single byte in a string.

There are two ways to access a byte in a string : substr() and $v[$pos].

The second style is more readable. It may be up to four times faster, though it is a micro-optimization. It is recommended to use it.

PHP 7.1 also introduces the support of negative offsets as string index : negative offset are also reported.

<?php

$string = 'ab人cde';

echo substr($string, $pos, 1);
echo $string[$pos];

echo mb_substr($string, $pos, 1);

// when $pos = 1
// displays bbb
// when $pos = 2
// displays ??人

?>

Beware that substr() and $v[$pos] are similar, while mb_substr() is not. The first function works on bytes, while the latter works on characters.

9.46.1. Suggestions

  • Replace substr() with the array notations for strings.
  • Replace substr() with a call to mb_substr().
Short name Structures/NoSubstrOne
Rulesets Analyze, Performances, CompatibilityPHP71, Suggestions, Top10, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples ChurchCRM, LiveZilla

9.47. Avoid Those Hash Functions

The following cryptography algorithms are considered insecure, and should be replaced with new and more performant algorithms.

MD2, MD4, MD5, SHA0, SHA1, CRC, DES, 3DES, RC2, RC4.

When possible, avoid using them, may it be as PHP functions, or hashing function configurations (mcrypt, hash…).

<?php

// Weak cryptographic algorithm
echo md5('The quick brown fox jumped over the lazy dog.');

// Weak crypotgraphic algorthim, used with a modern PHP extension (easier to update)
echo hash('md5', 'The quick brown fox jumped over the lazy dog.');

// Strong crypotgraphic algorthim, used with a modern PHP extension
echo hash('sha156', 'The quick brown fox jumped over the lazy dog.');

?>

Weak cryptography is commonly used for hashing values when caching them. In such cases, security is not a primary concern. However, it may later become such, when hackers get access to the cache folders, or if the cached identifier is published. As a preventive protection, it is recommended to always use a secure hashing function.

See also Secure Hash Algorithms.

9.47.1. Suggestions

  • Keep the current crypto, and add a call to a stronger one.
  • Change the crypto for a more modern one and update the related databases
Short name Security/AvoidThoseCrypto
Rulesets Security
Severity Major
Time To Fix Quick (30 mins)

9.48. Avoid Using stdClass

stdClass is the default class for PHP. It is instantiated when PHP needs to return a object, but no class is specifically available.

It is recommended to avoid instantiating this class, nor use it is any way.

<?php

$json = '{a:1,b:2,c:3}';
$object = json_decode($json);
// $object is a stdClass, as returned by json_decode

// Fast building of $o
$a = [];
$a['a'] = 1;
$a['b'] = 2;
$a['c'] = 3;
json_encode( (object) $a);

// Slow building of $o
$o = new stdClass();
$o->a = 1;
$o->b = 2;
$o->c = 3;
json_encode($o);

?>

If you need a stdClass object, it is faster to build it as an array, then cast it, than instantiate stdClass. This is a micro-optimisation.

9.48.1. Suggestions

  • Create a custom class to handle the properties
Short name Php/UseStdclass
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)

9.49. Avoid array_push()

array_push() is slower than the [] operator.

This is also true if the [] operator is called several times, while array_push() may be called only once. And using count after the push is also faster than collecting array_push() return value.

<?php

$a = [1,2,3];
// Fast version
$a[] = 4;

$a[] = 5;
$a[] = 6;
$a[] = 7;
$count = count($a);

// Slow version
array_push($a, 4);
$count = array_push($a, 5,6,7);

// Multiple version :
$a[] = 1;
$a[] = 2;
$a[] = 3;
array_push($a, 1, 2, 3);


?>

This is a micro-optimisation.

9.49.1. Suggestions

  • Use the [] operator
Short name Performances/AvoidArrayPush
Rulesets Performances
Severity Minor
Time To Fix Instant (5 mins)

9.50. Avoid array_unique()

The native function array_unique() is much slower than using other alternatives, such as array_count_values(), array_flip()/array_keys(), or even a foreach() loops.

<?php

// using array_unique()
$uniques = array_unique($someValues);

// When values are strings or integers
$uniques = array_keys(array_count_values($someValues));
$uniques = array_flip(array_flip($someValues))

//even some loops are faster.
$uniques = [];
foreach($someValues as $s) {
    if (!in_array($uniques, $s)) {
        $uniques[] $s;
    }
}

?>

See also array_unique.

9.50.1. Suggestions

  • Upgrade to PHP 7.2
  • Use an alternative way to make values unique in an array, using array_count_values(), for example.
Short name Structures/NoArrayUnique
Rulesets Performances
Php Version 7.2-
Severity Minor
Time To Fix Quick (30 mins)

9.51. Avoid get_class()

get_class() should be replaced with the instanceof operator to check the class of an object.

get_class() only compares the full namespace name of the object’s class, while instanceof actually resolves the name, using the local namespace and aliases.

<?php

    use Stdclass as baseClass;

    function foo($arg) {
        // Slow and prone to namespace errors
        if (get_class($arg) === 'Stdclass') {
            // doSomething()
        }
    }

    function bar($arg) {
        // Faster, and uses aliases.
        if ($arg instanceof baseClass) {
            // doSomething()
        }
    }
?>

See also get_class and Instanceof.

Short name Structures/UseInstanceof
Rulesets Analyze, Analyze, CI-checks, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.52. Avoid glob() Usage

glob() and scandir() sorts results by default. When that kind of sorting is not needed, save some time by requesting NOSORT with those functions.

Besides, whenever possible, use scandir() instead of glob().

<?php

// Scandir without sorting is the fastest.
scandir('docs/', SCANDIR_SORT_NONE);

// Scandir sorts files by default. Same as above, but with sorting
scandir('docs/');

// glob sorts files by default. Same as below, but no sorting
glob('docs/*', GLOB_NOSORT);

// glob sorts files by default. This is the slowest version
glob('docs/*');

?>

Using opendir() and a while loop may be even faster.

This analysis skips scandir() and glob() if they are expliciely configured with flags (aka, sorting is explicitly needed).

glob() accepts wildchar, such as *, that may not easily replaced with scandir() or opendir().

See also Putting glob to the test, How to list files recursively in a directory with PHP iterators and glob://.

9.52.1. Suggestions

  • Use FilesystemIterator, DirectoryIterator classes.
  • Use RegexIterator to filter any unwanted results from FilesystemIterator.
  • Use glob protocol for files : $it = new DirectoryIterator(‘glob://path/to/examples/*.php’);
Short name Performances/NoGlob
Rulesets Performances
Severity Major
Time To Fix Quick (30 mins)
Examples Phinx, NextCloud

9.53. Avoid mb_dectect_encoding()

mb_dectect_encoding() is bad at guessing encoding.

For example, UTF-8 and ISO-8859-1 share some common characters : when a string is build with them it is impossible to differentiate the actual encoding.

<?php

$encoding = mb_encoding_detect($_GET['name']);

?>

See also mb_encoding_detect, PHP vs. The Developer: Encoding Character Sets, DPC2019: Of representation and interpretation: A unified theory - Arnout Boks.

9.53.1. Suggestions

  • Store and transmit the data format
Short name Php/AvoidMbDectectEncoding
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.54. Avoid option arrays in constructors

Avoid option arrays in constructors. Use one parameter per injected element.

<?php

class Foo {
    // Distinct arguments, all typehinted if possible
    function __constructor(A $a, B $b, C $c, D $d) {
        $this->a = $a;
        $this->b = $b;
        $this->c = $c;
        $this->d = $d;
    }
}

class Bar {
    // One argument, spread over several properties
    function __constructor(array $options) {
        $this->a = $options['a'];
        $this->b = $options['b'];
        $this->c = $options['c'];
        $this->d = $options['d'];
    }
}

?>

See also Avoid option arrays in constructors.

9.54.1. Suggestions

  • Spread the options in the argument list, one argument each
  • Use a configuration class, that hold all the elements with clear names, instead of an array
Short name Classes/AvoidOptionArrays
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.55. Avoid set_error_handler $context Argument

Avoid configuring set_error_handler() with a method that accepts 5 arguments. The last argument, $errcontext, is deprecated since PHP 7.2, and will be removed later.

<?php

// setting error_handler with an incorrect closure
set_error_handler(function($errno, $errstr, $errfile, $errline) {});

// setting error_handler with an incorrect closure
set_error_handler(function($errno, $errstr, $errfile, $errline, $errcontext) {});

?>

See also set_error_handler();

9.55.1. Suggestions

  • Remove the 6th argument of registered handlers.
Short name Php/AvoidSetErrorHandlerContextArg
Rulesets CompatibilityPHP72
Severity Major
Time To Fix Slow (1 hour)
Examples shopware, Vanilla

9.56. Avoid sleep()/usleep()

sleep() and usleep() help saturate the web server.

Pausing the script for a specific amount of time means that the Web server is also making all related resources sleep, such as database, sockets, session, etc. This may used to set up a DOS on the server.

<?php

$begin = microtime(true);
checkLogin($user, $password);
$end   = microtime(true);

// Making all login checks looks the same
usleep(1000000 - ($end - $begin) * 1000000);

// Any hit on this page now uses 1 second, no matter if load is high or not
// Is it now possible to saturate the webserver in 1 s ?

?>

As much as possible, avoid delaying the end of the script.

sleep() and usleep() have less impact in commandline (CLI).

9.56.1. Suggestions

  • Add a deadline of usage in the session, and wait past this deadline to start serving again. Until then, abort immediately.
  • Use element in the GUI to delay or slow usage.
Short name Security/NoSleep
Rulesets Security
Severity Minor
Time To Fix Quick (30 mins)

9.57. Bad Constants Names

PHP’s manual recommends that developer do not use constants with the convention __NAME__. Those are reserved for PHP future use.

For example, __TRAIT__ recently appeared in PHP, as a magic constant. In the future, other may appear.

<?php

const __MY_APP_CONST__ = 1;

const __MY_APP_CONST__ = 1;

define('__MY_OTHER_APP_CONST__', 2);

?>

The analyzer will report any constant which name is __.*.__, or even _.*_ (only one underscore).

See also Constants.

9.57.1. Suggestions

  • Avoid using names that doesn’t comply with PHP’s convention
Short name Constants/BadConstantnames
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples PrestaShop, Zencart

9.58. Bad Typehint Relay

A bad typehint relay happens where a type hinted argument is relayed to a parameter with another typehint. This will lead to a Fatal error, and stop the code. This is possibly a piece of dead code.

<?php

// the $i argument is relayed to bar, which is expecting a string.
function foo(int $i) : string {
    return bar($i);
}

// the return value for the bar function is not compatible with the one from foo;
function bar(string $s) : int {
    return (int) $string + 1;
}

?>

It is recommended to harmonize the typehint, so the two functions are still compatible.

9.58.1. Suggestions

  • Harmonize the typehint so they match one with the other.
  • Remove dead code
  • Apply type casting before calling the next function, or return value
Short name Functions/BadTypehintRelay
Rulesets Typechecks
Severity Minor
Time To Fix Quick (30 mins)

9.59. Bail Out Early

When using conditions, it is recommended to quit in the current context, and avoid else clause altogether.

The main benefit is to make clear the method applies a condition, and stop immediately when it is not satisfied. The main sequence is then focused on the actual code.

This works with the break, continue, throw and goto keywords too, depending on situations.

<?php

// Bailing out early, low level of indentation
function foo1($a) {
    if ($a > 0) {
        return false;
    }

    $a++;
    return $a;
}

// Works with continue too
foreach($array as $a => $b) {
    if ($a > 0) {
        continue false;
    }

    $a++;
    return $a;
}

// No need for else
function foo2($a) {
    if ($a > 0) {
        return false;
    } else {
        $a++;
    }

    return $a;
}

// No need for else : return goes into then.
function foo3($a) {
    if ($a < 0) {
        $a++;
    } else {
        return false;
    }

    return $a;
}

// Make a return early, and make the condition visible.
function foo3($a) {
    if ($a < 0) {
        $a++;
        methodcall();
        functioncall();
    }
}

?>

See also Avoid nesting too deeply and return early (part 1) and Avoid nesting too deeply and return early (part 2).

9.59.1. Suggestions

  • Detect errors, and then, return as soon as possible.
  • When a if…then branches are unbalanced, test for the small branch, finish it with return. Then keep the other branch as the main code.
Short name Structures/BailOutEarly
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples OpenEMR, opencfp

9.60. Binary Glossary

List of all the integer values using the binary format.

<?php

$a = 0b10;
$b = 0B0101;

?>
Short name Type/Binary
Rulesets CompatibilityPHP53
Php Version With PHP 5.4 and more recent
Severity Major
Time To Fix Quick (30 mins)

9.61. Bracketless Blocks

PHP allows one liners as for(), foreach(), while(), do/while() loops, or as then/else expressions.

It is generally considered a bad practice, as readability is lower and there are non-negligible risk of excluding from the loop the next instruction.

<?php

// Legit one liner
foreach(range('a', 'z') as $letter) ++$letterCount;

// More readable version, even for a one liner.
foreach(range('a', 'z') as $letter) {
    ++$letterCount;
}

?>

switch() cannot be without bracket.

Short name Structures/Bracketless
Rulesets Coding Conventions
Severity Minor
Time To Fix Instant (5 mins)

9.62. Break Outside Loop

Starting with PHP 7, break or continue that are outside a loop (for, foreach(), do…`while() <https://www.php.net/manual/en/control-structures.while.php>`_, while()) or a switch() statement won’t compile anymore.

It is not possible anymore to include a piece of code inside a loop that will then break.

<?php

    // outside a loop : This won't compile
    break 1;

    foreach($array as $a) {
        break 1; // Compile OK

        break 2; // This won't compile, as this break is in one loop, and not 2
    }

    foreach($array as $a) {
        foreach($array2 as $a2) {
            break 2; // OK in PHP 5 and 7
        }
    }
?>
Short name Structures/BreakOutsideLoop
Rulesets Analyze, CompatibilityPHP70
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Slow (1 hour)

9.63. Break With 0

Cannot break 0, as this makes no sense. Break 1 is the minimum, and is the default value.

<?php
    // Can't break 0. Must be 1 or more, depending on the level of nesting.
    for($i = 0; $i < 10; $i++) {
        break 0;
    }

    for($i = 0; $i < 10; $i++) {
        for($j = 0; $j < 10; $j++) {
            break 2;
        }
    }

?>
Short name Structures/Break0
Rulesets CompatibilityPHP53
Php Version With PHP 5.4 and older
Severity Minor
Time To Fix Quick (30 mins)

9.64. Break With Non Integer

When using a break, the argument of the operator must be a positive non-null integer literal or be omitted.

Other values were acceptable in PHP 5.3 and previous version, but this is now reported as an error.

<?php
    // Can't break $a, even if it contains an integer.
    $a = 1;
    for($i = 0; $i < 10; $i++) {
        break $a;
    }

    // can't break on float
    for($i = 0; $i < 10; $i++) {
        for($j = 0; $j < 10; $j++) {
            break 2.2;
        }
    }

?>
Short name Structures/BreakNonInteger
Rulesets CompatibilityPHP54
Php Version With PHP 5.4 and older
Severity Minor
Time To Fix Quick (30 mins)

9.65. Buried Assignation

Those assignations are buried in the code, and placed in unexpected situations.

They are difficult to spot, and may be confusing. It is advised to place them in a more visible place.

<?php

// $b may be assigned before processing $a
$a = $c && ($b = 2);

// Display property p immeiately, but also, keeps the object for later
echo ($o = new x)->p;

// legit syntax, but the double assignation is not obvious.
for($i = 2, $j = 3; $j < 10; $j++) {

}
?>

9.65.1. Suggestions

  • Extract the assignation and set it on its own line, prior to the current expression.
  • Check if the local variable is necessary
Short name Structures/BuriedAssignation
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples XOOPS, Mautic

9.66. Cache Variable Outside Loop

Avoid recalculating constant values inside the loop.

Do the calculation once, outside the loops, and then reuse the value each time.

One of the classic example if doing count($array) in a for loop : since the source is constant during the loop, the result of count() is always the same.

<?php

$path = '/some/path';
$fullpath = realpath("$path/more/dirs/");
foreach($files as $file) {
    // Only moving parts are used in the loop
    copy($file, $fullpath.$file);
}

$path = '/some/path';
foreach($files as $file) {
    // $fullpath is calculated each loop
    $fullpath = realpath("$path/more/dirs/");
    copy($file, $fullpath.$file);
}

?>

Depending on the load of the called method, this may increase the speed of the loop from little to enormously.

9.66.1. Suggestions

  • Avoid using blind variables outside loops.
  • Store blind variables in local variables or properties for later reuse.
Short name Performances/CacheVariableOutsideLoop
Rulesets Performances

9.67. Callback Needs Return

When used with array_map() functions, the callback must return something. This return may be in the form of a return statement, a global variable or a parameter with a reference. All those solutions extract information from the callback.

<?php

// This filters each element
$filtered = array_filter($array, function ($x) {return $x == 2; });

// This return void for every element
$filtered = array_filter($array, function ($x) {return ; });

// costly array_sum()
$sum = 0;
$filtered = array_filter($array, function ($x) use (&$sum) {$sum += $x; });

// costly array_sum()
global $sum = 0;
$filtered = array_filter($array, function () {global $sum; $sum += $x; });

// register_shutown_function() doesn't require any return
register_shutown_function(my_shutdown);

?>

The following functions are omitted, as they don’t require the return :

See also array_map.

9.67.1. Suggestions

  • Add an explicit return to the callback
  • Use null to unset elements in an array without destroying the index
Short name Functions/CallbackNeedsReturn
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Instant (5 mins)
Examples Contao, Phpdocumentor

9.68. Calltime Pass By Reference

PHP doesn’t allow when a value is turned into a reference at functioncall, since PHP 5.4.

Either the function use a reference in its signature, either the reference won’t pass.

<?php

function foo($name) {
    $arg = ucfirst(strtolower($name));
    echo 'Hello '.$arg;
}

$a = 'name';
foo(&$a);

?>

9.68.1. Suggestions

  • Make the signature of the called method accept references
  • Remove the reference from the method call
  • Use an object instead of a scalar
Short name Structures/CalltimePassByReference
Rulesets CompatibilityPHP54
Php Version With PHP 5.4 and older
Severity Minor
Time To Fix Quick (30 mins)

9.69. Can’t Count Non-Countable

Count() emits an error when it tries to count scalars or objects what don’t implement Countable interface.

<?php

// Normal usage
$a = array(1,2,3,4);
echo count($a).items\n;

// Error emiting usage
$a = '1234';
echo count($a).chars\n;

// Error emiting usage
echo count($unsetVar).elements\n;

?>

See also Warn when counting non-countable types.

Short name Structures/CanCountNonCountable
Rulesets CompatibilityPHP72
Severity Major
Time To Fix Quick (30 mins)

9.70. Can’t Extend Final

It is not possible to extend final classes.

Since PHP fails with a fatal error, this means that the extending class is probably not used in the rest of the code. Check for dead code.

<?php
    // File Foo
    final class foo {
        public final function bar() {
            // doSomething
        }
    }
?>

In a separate file :

<?php
    // File Bar
    class bar extends foo {

    }
?>

See also Final Keyword.

9.70.1. Suggestions

  • Remove the final keyword
  • Remove the extending class
Short name Classes/CantExtendFinal
Rulesets Analyze, Dead code
Severity Critical
Time To Fix Instant (5 mins)

9.71. Can’t Throw Throwable

Classes extending Throwable can’t be thrown. The same applies to interfaces.

Although this code lints, PHP throws a Fatal error when executing or including it : Class fooThrowable cannot implement interface `Throwable <https://www.php.net/manual/en/class.throwable.php>`_, extend Exception or Error instead.

<?php

// This is the way to go
class fooException extends \Exception { }

// This is not possible and a lot of work
class fooThrowable implements \throwable { }

?>

See also Throwable, Exception and Error.

9.71.1. Suggestions

  • Extends the Exception class
  • Extends the Error class
Short name Exceptions/CantThrow
Rulesets Analyze, LintButWontExec
Severity Minor
Time To Fix Slow (1 hour)

9.72. Cancel Common Method

A parent method’s is too little used in children.

The parent class has a method, which is customised in children classes, though most of the time, those are empty : hence, cancelled.

<?php

class x {
    abstract function foo();
    abstract function bar();
}

class y1 extends x {
    function foo() { doSomething(); }
    function bar() { doSomething(); };
}

class y2 extends x {
    // foo is cancelled : it must be written, but has no use.
    function foo() {  }
    function bar() { doSomething(); };
}

?>

A threshold of cancelThreshold % of the children methods have to be cancelled to report the parent class. By default, it is 75 (or 3 out of 4).

9.72.1. Suggestions

  • Drop the common method, and the cancelled methods in the children
  • Fill the children’s methods with actual code
Name Default Type Description
cancelThreshold 75 integer Minimal number of cancelled methods to suggest the cancellation of the parent.
Short name Classes/CancelCommonMethod
Rulesets Suggestions, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.73. Cant Implement Traversable

It is not possible to implement the Traversable``interface. The alternative is to implement ``Iterator or IteratorAggregate.

Traversable may be useful when used with instanceof.

<?php

// This lints, but doesn't run
class x implements Traversable {

}

if( $argument instanceof Traversable ) {
    // doSomething
}

?>

See also Traversable, Iterator and IteratorAggregate..

9.73.1. Suggestions

  • Implement Iterator or IteratorAggregate
Short name Interfaces/CantImplementTraversable
Rulesets Analyze, LintButWontExec, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.74. Cant Inherit Abstract Method

Inheriting abstract methods was made available in PHP 7.2. In previous versions, it emitted a fatal error.

<?php

abstract class A           { abstract function bar(stdClass $x);  }
abstract class B extends A { abstract function bar($x): stdClass; }

//   Fatal error: Can't inherit abstract function A::bar()
?>

See also PHP RFC: Allow abstract function override.

9.74.1. Suggestions

  • Avoid inheriting abstract methods for compatibility beyond 7.2 (and older)
Short name Classes/CantInheritAbstractMethod
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.2 and more recent
Severity Critical
Time To Fix Quick (30 mins)

9.75. Cant Instantiate Class

When constructor is not public, it is not possible to instantiate such a class. Either this is a conception choice, or there are factories to handle that. Either way, it is not possible to call new on such class.

PHP reports an error similar to this one : ‘Call to private Y::__construct() from invalid context’.

<?php

//This is the way to go
$x = X::factory();

//This is not possible
$x = new X();

class X {
    //This is also the case with proctected __construct
    private function __construct() {}

    static public function factory() {
        return new X();
    }
}

?>

See also In a PHP5 class, when does a private constructor get called?, Named Constructors in PHP and PHP Constructor Best Practices And The Prototype Pattern.

Short name Classes/CantInstantiateClass
Rulesets Analyze
Severity Critical
Time To Fix Quick (30 mins)
Examples WordPress

9.76. Cant Use Return Value In Write Context

empty() used to work only on data containers, such as variables. Until PHP 5.5, it was not possible to use directly expressions, such as functioncalls, inside an empty() function call : they were met with a ‘Can’t use function return value in write context’ fatal error.

<?php

function foo($boolean) {
    return $boolean;
}

// Valid since PHP 5.5
echo empty(foo(true)) : 'true' : 'false';

?>

This also applies to methodcalls, static or not.

See also Cant Use Return Value In Write Context.

Short name Php/CantUseReturnValueInWriteContext
Rulesets CompatibilityPHP53, CompatibilityPHP54
Php Version With PHP 5.5 and more recent
Severity Major
Time To Fix Quick (30 mins)

9.77. Case Insensitive Constants

PHP constants may be case insensitive, when defined with define() and the third argument.

This feature is deprecated since PHP 7.3 and will be removed in PHP 8.0.

<?php

// case sensitive
define('A', 1);

// case insensitive
define('B', 1, true);

echo A;
// This is not possible
//echo a;

// both possible
echo B;
echo b;

?>

See also define.

Short name Constants/CaseInsensitiveConstants
Rulesets CompatibilityPHP73
Severity Critical
Time To Fix Slow (1 hour)

9.78. Cast To Boolean

This expression may be reduced by casting to boolean type.

<?php

$variable = $condition == 'met' ? 1 : 0;
// Same as
$variable = (bool) $condition == 'met';

$variable = $condition == 'met' ? 0 : 1;
// Same as (Note the condition inversion)
$variable = (bool) $condition != 'met';
// also, with an indentical condition
$variable = !(bool) $condition == 'met';

// This also works with straight booleans expressions
$variable = $condition == 'met' ? true : false;
// Same as
$variable = $condition == 'met';

?>

9.78.1. Suggestions

  • Remove the old expression and use (bool) operator instead
  • Change the target values from true/false, or 0/1 to non-binary values, like strings or integers beyond 0 and 1.
  • Complete the current branches with other commands
Short name Structures/CastToBoolean
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)
Examples MediaWiki, Dolibarr

9.79. Cast Unset Usage

Usage of the (unset) cast operator. It is removed in PHP 8.0, and was deprecated since PHP 7.2.0.

<?php

$a = 1;
(unset) $a;

// functioncall is OK
unset($a);

?>

See also Unset casting.

9.79.1. Suggestions

  • Replace (unset) with a call to unset().
  • Remove the unset call altogether.
Short name Php/CastUnsetUsage
Rulesets CompatibilityPHP80
Php Version 8.0-
Severity Minor
Time To Fix Quick (30 mins)

9.80. Casting Ternary

Type casting has a precedence over ternary operator, and is applied first. When this happens, the condition is cast, although it is often useless as PHP will do it if needed.

This applies to the ternary operator, the coalesce operator ?: and the null-coalesce operator ??.

<?php
    $a = (string) $b ? 3 : 4;
    $a = (string) $b ?: 4;
    $a = (string) $b ?? 4;
?>

The last example generates first an error Undefined variable: b, since $b is first cast to a string. The result is then an empty string, which leads to an empty string to be stored into $a. Multiple errors cascade.

See also Operators Precedence.

9.80.1. Suggestions

  • Add parenthesis around the ternary operator
  • Skip the casting
  • Cast in another expression
Short name Structures/CastingTernary
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)

9.81. Catch Overwrite Variable

The try/catch structure uses some variables that are also in use in this scope. In case of a caught exception, the exception will be put in the catch variable, and overwrite the current value, loosing some data.

<?php

// variables and caught exceptions are distinct
$argument = 1;
try {
    methodThatMayRaiseException($argument);
} (Exception $e) {
    // here, $e has been changed to an exception.
}

// variables and caught exceptions are overlapping
$e = 1;
try {
    methodThatMayRaiseException();
} (Exception $e) {
    // here, $e has been changed to an exception.
}

?>

It is recommended to use another name for these catch variables.

9.81.1. Suggestions

  • Use a standard : only use $e (or else) to catch exceptions. Avoid using them for anything else, parameter, property or local variable.
  • Change the variable, and keep the caught exception
Short name Structures/CatchShadowsVariable
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP no-catch-overwrite
Examples PhpIPAM, SuiteCrm

9.82. Catch Undefined Variable

Always initialize variable before the try block, when they are used in a catch block. If the exception is raised before the variable is defined, the catch block may have to handle an undefined variable, leading to more chaos.

<?php

$a = 1;
try {
    mayThrowAnException();
    $b = 2;
} catch (\Exception $e) {
    // $a is already defined, as it was done before the try block
    // $b may not be defined, as it was initialized after the exception-throwing expression
    echo $a + $b;
}

?>

9.82.1. Suggestions

  • Always define the variable used in the catch clause, before the try block.
Short name Exceptions/CatchUndefinedVariable
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.83. Check All Types

When checking for time, avoid using else. Mention explicitly all tested type, and raise an exception when reaching else.

PHP has a short list of scalar types : null, boolean, integer, real, strings, object, resource and array. When a variable is not holding one the the type, then it may be of any other type.

Most of the time, when using a simple is_string() / else test, this is relying on the conception of the code. By construction, the arguments may be one of two types : array or string.

What happens often is that in case of failure in the code (database not working, another class not checking its results), a third type is pushed to the structure, and it ends up breaking the execution.

The safe way is to check the various types all the time, and use the default case (here, the else) to throw exception() or test an assertion and handle the special case.

<?php

// hasty version
if (is_array($argument)) {
    $out = $argument;
} else {
    // Here, $argument is NOT an array. What if it is an object ? or a NULL ?
    $out = array($argument);
}

// Safe type checking : do not assume that 'not an array' means that it is the other expected type.
if (is_array($argument)) {
    $out = $argument;
} elseif (is_string($argument)) {
    $out = array($argument);
} else {
    assert(false, '$argument is not an array nor a string, as expected!');
}

?>

Using is_callable(), is_iterable() with this structure is fine : when variable is callable or not, while a variable is an integer or else.

Using a type test without else is also accepted here. This is a special treatment for this test, and all others are ignored. This aspect may vary depending on situations and projects.

9.83.1. Suggestions

  • Include a default case to handle all unknown situations
  • Include and process explicit types as much as possible
Short name Structures/CheckAllTypes
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)
Examples Zend-Config, Vanilla

9.84. Check Crypto Key Length

Each cryptography algorithm requires a reasonable length. Make sure an up-to-date length is used.

This rule use the following recommendations :

  • OPENSSL_KEYTYPE_RSA’ => 3072
  • OPENSSL_KEYTYPE_DSA’ => 2048
  • OPENSSL_KEYTYPE_DH’ => 2048
  • OPENSSL_KEYTYPE_EC’ => 512

The values above are used with the openssl PHP extension.

<?php

// Extracted from the documentation

// Generates a new and strong key
$private_key = openssl_pkey_new(array(
    private_key_type => OPENSSL_KEYTYPE_EC,
    private_key_bits => 1024,
));

// Generates a new and weak key
$private_key = openssl_pkey_new(array(
    private_key_type => OPENSSL_KEYTYPE_EC,
    private_key_bits => 256,
));

?>

See also The Definitive 2019 Guide to Cryptographic Key Sizes and Algorithm Recommendations and Cryptographic Key Length Recommendation.

9.84.1. Suggestions

Short name Security/CryptoKeyLength
Rulesets Security
Severity Minor
Time To Fix Quick (30 mins)

9.85. Check JSON

Check errors whenever JSON is encoded or decoded.

In particular, NULL is a valid decoded JSON response. If you want to avoid mistaking NULL for an error, it is recommended to call json_last_error.

<?php

$encoded = json_encode($incoming);
// Unless JSON must contains some non-null data, this mistakes NULL and error
if(json_last_error() != JSON_ERROR_NONE) {
    die('Error when encoding JSON');
}

$decoded = json_decode($incoming);
// Unless JSON must contains some non-null data, this mistakes NULL and error
if($decoded === null) {
    die('ERROR');
}

?>

See also Option to make json_encode and json_decode throw exceptions on errors, json_last_error.

9.85.1. Suggestions

  • Always check after JSON operation : encoding or decoding.
  • Add a call to json_last_error()
  • Configure operations to throw an exception upon error (JSON_THROW_ON_ERROR), and catch it.
Short name Structures/CheckJson
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples Woocommerce

9.86. Check On __Call Usage

When using the magic methods __call() and __staticcall(), make sure the method exists before calling it.

If the method doesn’t exists, then the same method will be called again, leading to the same failure. Finally, it will crash PHP.

<?php

class safeCall {
    function __class($name, $args) {
        // unsafe call, no checks
        if (method_exists($this, $name)) {
            $this->$name(...$args);
        }
    }
}

class unsafeCall {
    function __class($name, $args) {
        // unsafe call, no checks
        $this->$name(...$args);
    }
}

?>

See also Method overloading and ``Magical PHP: __call <https://www.garfieldtech.com/index.php/blog/magical-php-call>`_.

9.86.1. Suggestions

  • Add a call to method_exists() before using any method name
  • Relay the call to another object that doesn’t handle __call() or __callStatic()
Short name Classes/CheckOnCallUsage
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.87. Child Class Removes Typehint

PHP 7.2 introduced the ability to remove a typehint when overloading a method. This is not valid code for older versions.

<?php

class foo {
    function foobar(foo $a) {}
}

class bar extends foo {
    function foobar($a) {}
}

?>
Short name Classes/ChildRemoveTypehint
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56, Typechecks
Php Version With PHP 7.2 and more recent
Severity Major
Time To Fix Quick (30 mins)

9.88. Class Const With Array

Constant defined with const keyword may be arrays but only stating with PHP 5.6. Define never accept arrays : it only accepts scalar values.

Short name Php/ClassConstWithArray
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55
Php Version With PHP 5.5 and more recent
Severity Critical
Time To Fix Slow (1 hour)

9.89. Class Could Be Final

Any class that has no extension should be final by default.

As stated by Matthias Noback : If a class is not marked final, it has at least one subclass.

Prevent your classes from being subclassed by making them final. Sometimes, classes are not meant or thought to be derivable.

<?php

class x {}            // This class is extended
class y extends x {}  // This class is extended
class z extends y {}  // This class is not extended

final class z2 extends y {}  // This class is not extended

?>

See also Negative architecture, and assumptions about code.

9.89.1. Suggestions

  • Make the class final
  • Extends the class
Short name Classes/CouldBeFinal
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.90. Class Function Confusion

Avoid classes and functions bearing the same name.

When functions and classes bear the same name, calling them may be confusing. This may also lead to forgotten ‘new’ keyword.

<?php

class foo {}

function foo() {}

// Forgetting the 'new' operator is easy
$object = new foo();
$object = foo();

?>

9.90.1. Suggestions

  • Use a naming convention to distinguish functions and classes
  • Rename the class or the function (or both)
  • Use an alias with a use expression
Short name Php/ClassFunctionConfusion
Rulesets Semantics
Severity Minor
Time To Fix Slow (1 hour)

9.91. Class Should Be Final By Ocramius

‘Make your classes always final, if they implement an interface, and no other public methods are defined’.

When a class should be final, as explained by Ocramius (Marco Pivetta).

<?php

interface i1 {
    function i1() ;
}

// Class should final, as its public methods are in an interface
class finalClass implements i1 {
    // public interface
    function i1 () {}

    // private method
    private function a1 () {}
}

?>

See also When to declare classes final.

Short name Classes/FinalByOcramius
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)

9.92. Class Without Parent

Classes should not refer to parent when it is not extending another class.

In PHP 7.4, it is a Deprecated warning. In PHP 7.3, it was a Fatal error, when the code was finally executed.

<?php

class x {
    function foo() {
        parent::foo();
    }
}
?>

9.92.1. Suggestions

  • Update the class and make it extends another class
  • Change the parent mention with a fully qualified name
  • Remove the call to the parent altogether
Short name Classes/NoParent
Rulesets Analyze, ClassReview, CI-checks
Php Version 7.4-
Severity Minor
Time To Fix Quick (30 mins)

9.93. Class, Interface Or Trait With Identical Names

The following names are used at the same time for classes, interfaces or traits. For example,

<?php
    class a     { /* some definitions */ }
    interface a { /* some definitions */ }
    trait a     { /* some definitions */ }
?>

Even if they are in different namespaces, identical names makes classes easy to confuse. This is often solved by using alias at import time : this leads to more confusion, as a class suddenly changes its name.

Internally, PHP use the same list for all classes, interfaces and traits. As such, it is not allowed to have both a trait and a class with the same name.

In PHP 4, and PHP 5 before namespaces, it was not possible to have classes with the same name. They were simply included after a check.

9.93.1. Suggestions

  • Use distinct names for every class, trait and interface.
  • Keep eponymous classes, traits and interfaces in distinct files, for definition but also for usage. When this happens, rename one of them.
Short name Classes/CitSameName
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples shopware, NextCloud

9.94. Classes Mutually Extending Each Other

Those classes are extending each other, creating an extension loop. PHP will yield a fatal error at running time, even if it is compiling the code.

<?php

// This code is lintable but won't run
class Foo extends Bar { }
class Bar extends Foo { }

// The loop may be quite large
class Foo extends Bar { }
class Bar extends Bar2 { }
class Bar2 extends Foo { }

?>
Short name Classes/MutualExtension
Rulesets LintButWontExec, ClassReview
Severity Major
Time To Fix Quick (30 mins)

9.95. Clone With Non-Object

The clone keyword must be used on variables, properties or results from a function or method call.

clone cannot be used with constants or literals.

<?php

class x { }
$x = new x();

// Valid clone
$y = clone $x;

// Invalid clone
$y = clone x;

?>

Cloning a non-object lint but won’t execute.

See also Object cloning.

9.95.1. Suggestions

  • Only clone containers (like variables, properties…)
  • Add typehint to injected properties, so they are checked as objects.
Short name Classes/CloneWithNonObject
Rulesets Analyze, LintButWontExec
Severity Minor
Time To Fix Quick (30 mins)

9.96. Close Tags

PHP manual recommends that script should be left open, without the final closing ?>. This way, one will avoid the infamous bug ‘Header already sent’, associated with left-over spaces, that are lying after this closing tag.

Short name Php/CloseTags
Rulesets Coding Conventions
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP leave-last-closing-out

9.97. Closure Could Be A Callback

Closure or arrowfunction could be simplified to a callback. Callbacks are strings or arrays.

A simple closure that only returns arguments relayed to another function or method, could be reduced to a simpler expression. They

Closure may be simplified with a string, for functioncall, with an array for methodcalls and static methodcalls.

Performances : simplifying a closure tends to reduce the call time by 50%.

<?php

// Simple and faster call to strtoupper
$filtered = array_map('strtoupper', $array);

// Here the closure doesn't add any feature over strtoupper
$filtered = array_map(function ($x) { return strtoupper($x);}, $array);

// Methodcall example : no fix
$filtered = array_map(function ($x) { return $x->strtoupper() ;}, $array);

// Methodcall example  : replace with array($y, 'strtoupper')
$filtered = array_map(function ($x) use ($y) { return $y->strtoupper($x) ;}, $array);

// Static methodcall example
$filtered = array_map(function ($x) { return $x::strtoupper() ;}, $array);

// Static methodcall example   : replace with array('A', 'strtoupper')
$filtered = array_map(function ($x) { return A::strtoupper($x) ;}, $array);

?>

See also Closure class and Callbacks / Callables.

9.97.1. Suggestions

  • Replace the closure by a string, with the name of the called function
  • Replace the closure by an array, with the name of the called method and the object as first element
Short name Functions/Closure2String
Rulesets Suggestions, Performances
Severity Minor
Time To Fix Quick (30 mins)
Examples Tine20, NextCloud

9.98. Closure May Use $this

$this is automatically accessible to closures.

When closures were introduced in PHP, they couldn’t use the $this variable, making is cumbersome to access local properties when the closure was created within an object.

<?php

// Invalid code in PHP 5.4 and less
class Test
{
    public function testing()
    {
        return function() {
            var_dump($this);
        };
    }
}

$object = new Test;
$function = $object->testing();
$function();

?>

This is not the case anymore since PHP 5.4.

See also Anonymous functions.

Short name Php/ClosureThisSupport
Rulesets CompatibilityPHP53
Php Version With PHP 5.4 and older
Severity Minor
Time To Fix Quick (30 mins)

9.99. Coalesce And Concat

The concatenation operator dot has precedence over the coalesce operator ??.

<?php

// Parenthesis are the right solution when in doubt
echo a . ($b ?? 'd') . $e;

// 'a' . $b is evaluated first, leading ot a useless ?? operator
'a' . $b ?? $c;

// 'd' . 'e' is evaluated first, leading to $b OR 'de'.
echo $b ?? 'd' . 'e';

?>

9.99.1. Suggestions

  • Add parenthesis around ?? operator to avoid misbehavior
  • Do not use dot and ?? together in the same expression
Short name Structures/CoalesceAndConcat
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.100. Coalesce Equal

Usage of coalesce assignement operator. The operator is available in PHP since PHP 7.4.

<?php

// Coalesce operator, since PHP 5.3
$a ??= 'default value';

// Equivalent to $a = $a ?? 'default value';

?>

See also Ternary Operator.

Short name Php/CoalesceEqual
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP73, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.4 and more recent

9.101. Common Alternatives

In the following conditional structures, expressions were found that are common to both ‘then’ and ‘else’. It may be interesting, though not always possible, to put them both out of the conditional, and reduce line count.

<?php
if ($c == 5) {
    $b = strtolower($b[2]);
    $a++;
} else {
    $b = strtolower($b[2]);
    $b++;
}
?>

may be rewritten in :

<?php

$b = strtolower($b[2]);
if ($c == 5) {
    $a++;
} else {
    $b++;
}

?>

9.101.1. Suggestions

  • Collect common expressions, and move them before of after the if/then expression.
  • Move a prefix and suffixes to a third-party method
Short name Structures/CommonAlternatives
Rulesets Analyze
Severity Major
Time To Fix Instant (5 mins)
Examples Dolibarr, NextCloud

9.102. Compact Inexistant Variable

Compact() doesn’t warn when it tries to work on an inexistant variable. It just ignores the variable.

This behavior changed in PHP 7.3, and compact() now emits a warning when the compacted variable doesn’t exist.

<?php

function foo($b = 2) {
    $a = 1;
    // $c doesn't exists, and is not compacted.
    return compact('a', 'b', 'c');
}
?>

For performances reasons, this analysis only works inside methods and functions.

See also compact and PHP RFC: Make compact function reports undefined passed variables.

9.102.1. Suggestions

  • Fix the name of variable in the compact() argument list
  • Remove the name of variable in the compact() argument list
Short name Php/CompactInexistant
Rulesets Suggestions, CompatibilityPHP73
Severity Major
Time To Fix Quick (30 mins)

9.103. Compare Hash

When comparing hash values, it is important to use the strict comparison : hash_equals(), === or !==.

In a number of situations, the hash value will start with 0e, and PHP will understand that the comparison involves integers : it will then convert the strings into numbers, and it may end up converting them to 0.

Here is an example :

<?php

// The two following passwords hashes matches, while they are not the same.
$hashed_password = 0e462097431906509000000000000;
if (hash('md5','240610708',false) == $hashed_password) {
  print 'Matched.'.PHP_EOL;
}

// hash returns a string, that is mistaken with 0 by PHP
// The strength of the hashing algorithm is not a problem
if (hash('ripemd160','20583002034',false) == '0') {
  print 'Matched.'.PHP_EOL;
}

if (hash('md5','240610708',false) !== $hashed_password) {
  print 'NOT Matched.'.PHP_EOL;
}

// Display true
var_dump(md5('240610708') == md5('QNKCDZO') );

?>

You may also use password_hash() and password_verify() : they work together without integer conversion problems, and they can’t be confused with a number.

See also Magic Hashes What is the best way to compare hashed strings? (PHP) and md5(‘240610708’) == md5(‘QNKCDZO’).

9.103.1. Suggestions

  • Use dedicated functions for hash comparisons
  • Use identity operators (===), and not equality operators (==) to compare hashes
  • Compare hashes in the database (or external system), where such confusion is not possible
Short name Security/CompareHash
Rulesets Security
Severity Major
Time To Fix Quick (30 mins)
ClearPHP strict-comparisons
Examples Traq, LiveZilla

9.104. Compared Comparison

Usually, comparison are sufficient, and it is rare to have to compare the result of comparison. Check if this two-stage comparison is really needed.

<?php

if ($a === strpos($string, $needle) > 2) {}

// the expression above apply precedence :
// it is equivalent to :
if (($a === strpos($string, $needle)) > 2) {}

?>

See also Operators Precedence.

Short name Structures/ComparedComparison
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.105. Complex Dynamic Names

Avoid using expressions as names for variables or methods.

There are no place for checks or flow control, leading to any rogue value to be used as is. Besides, the expression is often overlooked, and not expected there : this makes the code less readable.

It is recommended to build the name in a separate variable, apply the usual checks for existence and validity, and then use the name.

<?php

$a = new foo();

// Code is more readable
$name = strolower($string);
if (!property_exists($a, $name)) {
    throw new missingPropertyexception($name);
}
echo $a->$name;

// This is not check
echo $a->{strtolower($string)};

?>

This analysis only accept simple containers, such as variables, properties.

See also Dynamically Access PHP Object Properties with `$this <https://drupalize.me/blog/201508/dynamically-access-php-object-properties>`_.

9.105.1. Suggestions

  • Extract the expression from the variable syntax, and make it a separate variable.
Short name Variables/ComplexDynamicNames
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.106. Concat And Addition

Precedence between addition and concatenation has changed. In PHP 7.4, addition has precedence, and before, addition and concatenation had the same precedence.

From the RFC : Currently the precedence of '.', '+' and '-' operators are equal. Any combination of these operators are simply evaluated left-to-right.

This is counter-intuitive though: you rarely want to add or subtract concatenated strings which in general are not numbers. However, given PHP’s capability of seamlessly converting an integer to a string, concatenation of these values is desired.``

<?php
// Extracted from the RFC
echo sum: . $a + $b;

// current behavior: evaluated left-to-right
echo (sum: . $a) + $b;

// desired behavior: addition and subtraction have a higher precendence
echo sum : . ($a + $b);

?>

This analysis reports any addition and concatenation that are mixed, without parenthesis. Addition also means substraction here, aka using + or -.

The same applies to bitshift operations, << and >>. There is no RFC for this change.

See also Change the precedence of the concatenation operator.

9.106.1. Suggestions

  • Add parenthesis around the addition to ensure its expected priority
  • Move the addition outside the concatenation
Short name Php/ConcatAndAddition
Rulesets Analyze, CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP73, CompatibilityPHP54, CompatibilityPHP74, CompatibilityPHP80, CompatibilityPHP55, CompatibilityPHP56, Top10, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.107. Concat Empty String

Using a concatenation to make a value a string should be replaced with a type cast.

Type cast to a string is done with (string) operator. There is also the function strval(), although it is less recommended.

<?php

$a = 3;

// explicite way to cast a value
$b = (string) $a; // $b is a string with the content 3

// Wrong way to cast a value
$c = $a . ''; // $c is a string with the content 3
$c = '' . $a; // $c is a string with the content 3
$a .= '';     // $a is a string with the content 3

// Wrong way to cast a value
$c = $a . '' . $b; // This is not reported. The empty string is useless, but not meant to type cast

?>

See also Type Casting and PHP Type Casting.

9.107.1. Suggestions

  • Avoid concatenating with empty strings
  • Use (string) operator to cast to string
  • Remove any concatenated empty string
Short name Structures/ConcatEmpty
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.108. Concrete Visibility

Methods that implements an interface in a class must be public.

PHP does lint this, unless the interface and the class are in the same file. At execution, it stops immediately with a Fatal error : ‘Access level to c::iPrivate() must be public (as in class i) ‘;

<?php

interface i {
    function iPrivate() ;
    function iProtected() ;
    function iPublic() ;
}

class c implements i {
    // Methods that implements an interface in a class must be public.
    private function iPrivate() {}
    protected function iProtected() {}
    public function iPublic() {}
}

?>

See also Interfaces.

9.108.1. Suggestions

  • Always set interface methods to public.
Short name Interfaces/ConcreteVisibility
Rulesets Analyze, LintButWontExec
Severity Major
Time To Fix Instant (5 mins)

9.109. Configure Extract

The extract() function overwrites local variables when left unconfigured.

Extract imports variables from an array into the local scope. In case of a conflict, that is when a local variable already exists, it overwrites the previous variable.

In fact, extract() may be configured to handle the situation differently : it may skip the conflicting variable, prefix it, prefix it only if it exists, only import overwriting variables… It may also import them as references to the original values.

This analysis reports extract() when it is not configured explicitly. If overwriting is the intended objective, it is not reported.

<?php

// ignore overwriting variables
extract($array, EXTR_SKIP);

// prefix all variables explicitly variables with 'php_'
extract($array, EXTR_PREFIX_ALL, 'php_');

// overwrites explicitly variables
extract($array, EXTR_OVERWRITE);

// overwrites implicitely variables : do we really want that?
extract($array, EXTR_OVERWRITE);

?>

Always avoid using extract() on untrusted sources, such as $_GET, $_POST, $_FILES, or even databases records.

See also extract.

9.109.1. Suggestions

  • Always use the second argument of extract(), and avoid using EXTR_OVERWRITE
Short name Security/ConfigureExtract
Rulesets Security
Severity Minor
Time To Fix Instant (5 mins)
Examples Zurmo, Dolibarr

9.110. Const Visibility Usage

Visibility for class constant controls the accessibility to class constant.

A public constant may be used anywhere in the code; a protected constant usage is restricted to the class and its relatives; a private constant is restricted to itself.

This feature was introduced in PHP 7.1. It is recommended to use explicit visibility, and, whenever possible, make the visibility private.

<?php

class x {
    public const a = 1;
    protected const b = 2;
    private const c = 3;
    const d = 4;
}

interface i {
    public const a = 1;
      const d = 4;
}

?>

See also Class Constants and PHP RFC: Support Class Constant Visibility.

9.110.1. Suggestions

  • Add constant visibility, at least ‘public’.
Short name Classes/ConstVisibilityUsage
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.1 and more recent
Severity Minor
Time To Fix Slow (1 hour)

9.111. Const With Array

The const keyword supports array. This feature was added in PHP 5.6.

The array must be filled with other constants. It may also be build using the ‘+’ operator.

<?php

const PRIMES = [2, 3, 5, 7];

class X {
    const TWENTY_THREE = 23;
    const MORE_PRIMES = PRIMES + [11, 13, 17, 19];
    const EVEN_MORE_PRIMES = self::MORE_PRIMES + [self::TWENTY_THREE];
}

?>

See also Class Constants and Constants Syntax.

Short name Php/ConstWithArray
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55
Php Version With PHP 5.5 and more recent
Severity Major
Time To Fix Slow (1 hour)

9.112. Constant Class

A class or an interface only made up of constants. Constants usually have to be used in conjunction of some behavior (methods, class…) and never alone.

<?php

class ConstantClass {
    const KBIT = 1000;
    const MBIT = self::KBIT * 1000;
    const GBIT = self::MBIT * 1000;
    const PBIT = self::GBIT * 1000;
}

?>

As such, they should be PHP constants (build with define or const), or included in a class with other methods and properties.

See also PHP Classes containing only constants.

9.112.1. Suggestions

  • Make the class an interface
  • Make the class an abstract class, to avoid its instantiation
Short name Classes/ConstantClass
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Slow (1 hour)

9.113. Constant Comparison

Constant to the left or right is a favorite.

Comparisons are commutative : they may be $a == B or B == $a. The analyzed code show less than 10% of one of the two : for consistency reasons, it is recommended to make them all the same.

Putting the constant on the left is also called ‘Yoda Comparison’, as it mimics the famous characters style of speech. It prevents errors like ‘B = $a’ where the comparison is turned into an assignation.

The natural way is to put the constant on the right. It is often less surprising.

Every comparison operator is used when finding the favorite.

<?php

//
if ($a === B) { doSomething(); }
if ($c > D) { doSomething(); }
if ($e !== G) { doSomething(); }
do { doSomething(); } while ($f === B);
while ($a === B) { doSomething(); }

// be consistent
if (B === $a) {}

// Compari
if (B <= $a) {}

?>
Short name Structures/ConstantComparisonConsistance
Rulesets Coding Conventions
Severity Minor
Time To Fix Quick (30 mins)

9.114. Constant Scalar Expressions

Define constant with the result of static expressions. This means that constants may be defined with the const keyword, with the help of various operators but without any functioncalls.

This feature was introduced in PHP 5.6. It also supports array(), and expressions in arrays.

Those expressions (using simple operators) may only manipulate other constants, and all values must be known at compile time.

<?php

// simple definition
const A = 1;

// constant scalar expression
const B = A * 3;

// constant scalar expression
const C = [A ** 3, '3' => B];

?>

See also Constant Scalar Expressions.

Short name Structures/ConstantScalarExpression
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55
Php Version With PHP 5.6 and more recent
Severity Major
Time To Fix Quick (30 mins)

9.115. Constants Created Outside Its Namespace

Constants Created Outside Its Namespace.

Using the define() function, it is possible to create constant outside their namespace, but using the fully qualified namespace.

<?php

namespace A\B {
    // define A\B\C as 1
    define('C', 1);
}

namespace D\E {
    // define A\B\C as 1, while outside the A\B namespace
    define('A\B\C', 1);
}

?>

However, this makes the code confusing and difficult to debug. It is recommended to move the constant definition to its namespace.

Short name Constants/CreatedOutsideItsNamespace
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)

9.116. Constants With Strange Names

List of constants being defined with names that are incompatible with PHP standards.

<?php

// Define a valid PHP constant
define('ABC', 1);
const ABCD = 2;

// Define an invalid PHP constant
define('ABC!', 1);
echo defined('ABC!') ? constant('ABC!') : 'Undefined';

// Const doesn't allow illegal names

?>

See also PHP Constants.

Short name Constants/ConstantStrangeNames
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Slow (1 hour)

9.117. Continue Is For Loop

break and continue are very similar in PHP : they both break out of loop or switch. Yet, continue should be reserved for loops.

Since PHP 7.3, the execution will emit a warning when finding a continue inside a switch inside a loop : ‘”continue” targeting switch is equivalent to “break”. Did you mean to use “continue 2”?’

<?php

while ($foo) {
    switch ($bar) {
        case 'baz':
            continue; // In PHP: Behaves like 'break;'
                      // In C:   Behaves like 'continue 2;'
    }
}

?>

See also Deprecate and remove `continue targeting switch <https://wiki.php.net/rfc/continue_on_switch_deprecation>`_.

9.117.1. Suggestions

  • Replace break by continue
Short name Structures/ContinueIsForLoop
Rulesets Analyze, CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56, CompatibilityPHP73
Severity Minor
Time To Fix Quick (30 mins)
Examples XOOPS

9.118. Could Be Abstract Class

An abstract class is never instantiated, and has children class that are. As such, a ‘parent’ class that is never instantiated by itself, but has its own children instantiated could be marked as abstract.

That will prevent new code to try to instantiate it.

<?php

// Example code would actually be split over multiple files.


// That class could be abstract
class motherClass {}

// Those classes shouldn't be abstract
class firstChildren extends motherClass {}
class secondChildren extends motherClass {}
class thirdChildren extends motherClass {}

new firstChildren();
new secondChildren();
new thirdChildren();

//Not a single : new motherClass()

?>

See also Class Abstraction Abstract classes and methods.

9.118.1. Suggestions

  • Make this class an abstract class
Short name Classes/CouldBeAbstractClass
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)
Examples Edusoho, shopware

9.119. Could Be Callable

Mark arguments and return types that can be set to callable.

<?php

// Accept a callable as input
function foo($b) {
    // Returns value as return
    return $b();
}

?>

9.119.1. Suggestions

  • Add callable typehint to the code.
Short name Typehints/CouldBeCallable
Rulesets Typechecks
Severity Major
Time To Fix Quick (30 mins)
Precision High

9.120. Could Be Class Constant

When a property is defined and read, but never modified, it may be a constant.

<?php

class foo {
    // $this->bar is never modified.
    private $bar = 1;

    // $this->foofoo is modified, at least once
    private $foofoo = 2;

    function method($a) {
        $this->foofoo = $this->bar + $a + $this->foofoo;

        return $this->foofoo;
    }

}

?>

Starting with PHP 5.6, even array() may be defined as constants.

Short name Classes/CouldBeClassConstant
Rulesets ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.121. Could Be Constant

Literals may be replaced by an existing constant.

Constants makes the code easier to read, as they may bear a meaningful name. They also hide implementation values, with a readable name, such as const READABLE= true;. Later, upgrading constant values is easier than scouring the code with a new literal.

Not all literal can be replaced by a constant values : sometimes, literal may have the same literal value, but different meanings. Check with your application semantics before changing any literal with a constant.

<?php

const A = 'abc';
define('B', 'ab');

class foo {
    const X = 'abcd';
}

// Could be replaced by B;
$a = 'ab';

// Could be replaced by A;
$a = 'abc';

// Could be replaced by foo::X;
$a = 'abcd';

?>

This analysis currently doesn’t support arrays.

This analysis also skips very common values, such as boolean, 0 and 1. This prevents too many false positive.

9.121.1. Suggestions

  • Turn the literal into an existing constant
Short name Constants/CouldBeConstant
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.122. Could Be Else

Merge opposition conditions into one if/then structure.

When two if/then structures follow each other, using a condition and its opposite, they may be merged into one.

<?php

// Short version
if ($a == 1) {
    $b = 2;
} else {
    $b = 1;
}

// Long version
if ($a == 1) {
    $b = 2;
}

if ($a != 1) {
    $b = 3;
}

?>

9.122.1. Suggestions

  • Merge the two conditions into one structure
  • Check if the second condition is still applicable
Short name Structures/CouldBeElse
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)
Examples SugarCrm, OpenEMR

9.123. Could Be Float

Mark arguments, properties and return types that can be set to float.

<?php

// Accept an int as input
function foo($b) {
    // Returns a float (cubic root of $b);
    return pow($b, 1 / 3);
}

?>

9.123.1. Suggestions

  • Add float typehint to the code.
Short name Typehints/CouldBeFloat
Rulesets Typechecks
Severity Major
Time To Fix Quick (30 mins)
Precision High

9.124. Could Be Integer

Mark arguments, properties and return types that can be set to int.

<?php

// Accept an int as input
function foo($b) {
    // Returns an int
    return $b + 8;
}

?>

9.124.1. Suggestions

  • Add int typehint to the code.
Short name Typehints/CouldBeInt
Rulesets Typechecks
Severity Major
Time To Fix Quick (30 mins)
Precision High

9.125. Could Be Iterable

Mark arguments, properties and return types that can be set to iterable.

<?php

// Accept an array or a traversable Object as input
function foo($b) {
    foreach($b as $c) {

    }

    // Returns an array
    return [$b];
}

?>

9.125.1. Suggestions

  • Add iterable typehint to the code (PHP 8.0+).
Short name Typehints/CouldBeIterable
Rulesets Typechecks
Severity Major
Time To Fix Quick (30 mins)
Precision High

9.126. Could Be Null

Mark arguments and return types that can be null.

<?php

// Accept null as input, when used as third argument of file_get_contents
function foo($b) {
    $s = file_get_contents(URL, false, $b);

    // Returns a string
    return shell_exec($s);
}

?>

9.126.1. Suggestions

  • Add null typehint to the code (PHP 8.0+).
  • Add ? typehint to the code.
Short name Typehints/CouldBeNull
Rulesets Typechecks
Severity Major
Time To Fix Quick (30 mins)
Precision High

9.127. Could Be Parent

Mark arguments, return types and properties that can be set to parent.

This analysis works when typehints have already been configured.

<?php

class x extends w {
    // Accept a w object as input
    function foo(w $b) : w {
        // Returns a w object
        return $b;
    }
}

?>

9.127.1. Suggestions

  • Add parent typehint to the code.
  • Add the literal class/type typehint to the code.
Short name Typehints/CouldBeParent
Rulesets Typechecks
Severity Major
Time To Fix Quick (30 mins)
Precision High

9.128. Could Be Parent Method

A method is defined in several children, but not in a the parent class. It may be worth checking if this method doesn’t belong the parent class, as an abstraction.

<?php

// The parent class
class x { }

// The children class
class y1 extends x {
    // foo is common to y1 and y2, so it shall be also a method in x
    function foo() {}
    // fooY1 is specific to y1
    function fooY1() {}
}

class y2 extends x {
    function foo() {}
    // fooY2 is specific to y1
    function fooY2() {}
}

?>

Only the name of the method is used is for gathering purposes. If the code has grown organically, the signature (default values, typehint, argument names) may have followed different path, and will require a refactorisation.

9.128.1. Suggestions

  • Create an abstract method in the parent
  • Create an concrete method in the parent, and move default behavior there by removing it in children classes
Name Default Type Description
minChildren 4 integer Minimal number of children using this method.
Short name Classes/CouldBeParentMethod
Rulesets ClassReview
Severity Minor
Time To Fix Slow (1 hour)

9.129. Could Be Private Class Constant

Class constant may use private visibility.

Since PHP 7.1, constants may also have a public/protected/private visibility. This restrict their usage to anywhere, class and children or class.

As a general rule, it is recommended to make constant private by default, and to relax this restriction as needed. PHP makes them public by default.

<?php

class foo {
    // pre-7.1 style
    const PRE_71_CONSTANT = 1;

    // post-7.1 style
    private const PRIVATE_CONSTANT = 2;
    public const PUBLIC_CONSTANT = 3;

    function bar() {
        // PRIVATE CONSTANT may only be used in its class
        echo self::PRIVATE_CONSTANT;
    }
}

// Other constants may be used anywhere
function x($a = foo::PUBLIC_CONSTANT) {
    echo $a.' '.foo:PRE_71_CONSTANT;
}

?>

Constant shall stay public when the code has to be compatible with PHP 7.0 and older.

They also have to be public in the case of component : some of those constants have to be used by external actors, in order to configure the component.

See also Class Constants.

Short name Classes/CouldBePrivateConstante
Rulesets ClassReview
Severity Minor
Time To Fix Quick (30 mins)
Examples Phinx

9.130. Could Be Protected Class Constant

Class constant may use ‘protected’ visibility.

Since PHP 7.1, constants may also have a public/protected/private visibility. This restrict their usage to anywhere, class and children or class.

As a general rule, it is recommended to make constant ‘private’ by default, and to relax this restriction as needed. PHP makes them public by default.

<?php

class foo {
    // pre-7.1 style
    const PRE_71_CONSTANT = 1;

    // post-7.1 style
    protected const PROTECTED_CONSTANT = 2;
    public const PUBLIC_CONSTANT = 3;
}

class foo2 extends foo {
    function bar() {
        // PROTECTED_CONSTANT may only be used in its class or its children
        echo self::PROTECTED_CONSTANT;
    }
}

class foo3 extends foo {
    function bar() {
        // PROTECTED_CONSTANT may only be used in its class or any of its children
        echo self::PROTECTED_CONSTANT;
    }
}

// Other constants may be used anywhere
function x($a = foo::PUBLIC_CONSTANT) {
    echo $a.' '.foo:PRE_71_CONSTANT;
}

?>
Short name Classes/CouldBeProtectedConstant
Rulesets ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.131. Could Be Protected Method

Those methods are declared public, but are never used publicly. They may be made protected.

<?php

class foo {
    // Public, and used publicly
    public publicMethod() {}

    // Public, but never used outside the class or its children
    public protectedMethod() {}

    private function bar() {
        $this->protectedMethod();
    }
}

$foo = new Foo();
$foo->publicMethod();

?>

These properties may even be made private.

Short name Classes/CouldBeProtectedMethod
Rulesets ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.132. Could Be Protected Property

Those properties are declared public, but are never used publicly. They may be made protected.

<?php

class foo {
    // Public, and used publicly
    public $publicProperty;
    // Public, but never used outside the class or its children
    public $protectedProperty;

    function bar() {
        $this->protectedProperty = 1;
    }
}

$foo = new Foo();
$foo->publicProperty = 3;

?>

This property may even be made private.

Short name Classes/CouldBeProtectedProperty
Rulesets ClassReview
Severity Minor
Time To Fix Slow (1 hour)

9.133. Could Be Self

Mark arguments, return types and properties that can be set to self.

This analysis works when typehints have already been configured.

<?php

class x {
    // Accept a x object as input
    function foo(x $b) : x {
        // Returns a x object
        return $b;
    }
}

?>

9.133.1. Suggestions

  • Add self typehint to the code.
  • Add the literal class/type typehint to the code.
Short name Typehints/CouldBeSelf
Rulesets Typechecks
Severity Major
Time To Fix Quick (30 mins)
Precision High

9.134. Could Be Static

This global is only used in one function or method. It may be called ‘static’, instead of global. This allows you to keep the value between call to the function, but will not be accessible outside this function.

<?php
function foo( ) {
    static $variableIsReservedForX; // only accessible within foo( ), even between calls.
    global $variableIsGlobal;       //      accessible everywhere in the application
}
?>
Short name Structures/CouldBeStatic
Rulesets Analyze, ClassReview, Analyze, ClassReview
Severity Major
Time To Fix Quick (30 mins)
Examples Dolphin, Contao

9.135. Could Be Static Closure

Closure may be static, and prevent the import of $this.

By preventing the useless import of $this, you avoid useless work.

This also has the added value to prevent the usage of $this from the closure. This is a good security practice.

<?php

class Foo
{
    function __construct()
    {

        // Not possible to use $this
        $func = static function() {
            var_dump($this);
        };
        $func();

        // Normal import of $this
        $closure = function() {
            var_dump($this);
        };
    }
};
new Foo();

?>

This is a micro-optimisation. Apply it in case of intensive usage.

See also Anonymous functions, GeneratedHydrator and Static anonymous functions <https://www.php.net/manual/en/functions.anonymous.php#functions.anonymous-functions.`static>`_.

9.135.1. Suggestions

  • Add the static keyword to the closure.
  • Make actual usage of $this in the closure.
Short name Functions/CouldBeStaticClosure
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)
Examples Piwigo

9.136. Could Be String

Mark arguments and return types that can be set to string.

<?php

// Accept a string as input
function foo($a) {
    // Returns a string
    return $a . 'string';
}

?>

9.136.1. Suggestions

  • Choose the string typehint, and add it to the code.
Short name Typehints/CouldBeString
Rulesets Typechecks
Severity Major
Time To Fix Quick (30 mins)
Precision High

9.137. Could Be Stringable

Stringable is an interface that mark classes as string-castable. It is introduced in PHP 8.0.

Classes that defined a __toString() magic method may be turned into a string when the typehint, argument, return or property, requires it. This is not the case when strict_types is activated. Yet, until PHP 8.0, there was nothing to identify a class as such.

<?php

// This class may implement Stringable
class x {
    function __tostring() {
        return 'asd';
    }
}

echo (new x);

?>

See also PHP RFC: Add Stringable interface.

9.137.1. Suggestions

Short name Classes/CouldBeStringable
Rulesets Analyze, LintButWontExec
Php Version 8.0+
Severity Minor
Time To Fix Quick (30 mins)

9.138. Could Be Void

Mark return types that can be set to void.

<?php

// No return, this should be void.
function foo() {
    ++$a; // Not useful
}

?>

All abstract methods (in classes or in interfaces) are omitted here.

9.138.1. Suggestions

  • Add the void typehint to the code.
Short name Typehints/CouldBeVoid
Rulesets Typechecks
Severity Major
Time To Fix Quick (30 mins)
Precision High

9.139. Could Make A Function

When a function is called across the code with the same arguments often enough, it should be turned into a local API.

This approach is similar to turning literals into constants : it centralize the value, it helps refactoring by updating it. It also makes the code more readable. Moreover, it often highlight common grounds between remote code locations.

The analysis looks for functions calls, and checks the arguments. When the calls occurs more than 4 times, it is reported.

<?php

// str_replace is used to clean '&' from strings.
// It should be upgraded to a central function
function foo($arg ) {
    $arg = str_replace('&', '', $arg);
    // do something with $arg
}

class y {
    function bar($database ) {
        $value = $database->queryName();
        $value = str_replace('&', '', $value);
        // $value = removeAmpersand($value);
        // do something with $arg2
    }
}

// helper function
function removeAmpersand($string) {
    return str_replace('&', '', $string);
}

?>

See also Don’t repeat yourself (DRY).

9.139.1. Suggestions

  • Create a constant for common pieces of data
  • Create a function based on context-free repeated elements
  • Create a class based on repeated elements with dependent values
Name Default Type Description
centralizeThreshold 8 integer Minimal number of calls of the function with one common argument.
Short name Functions/CouldCentralize
Rulesets Analyze, Suggestions
Severity Minor
Time To Fix Slow (1 hour)

9.140. Could Use Alias

This long name may be reduced by using an available alias.

This applies to classes (as full name or prefix), and to constants and functions.

<?php

use a\b\c;
use function a\b\c\foo;
use const a\b\c\D;

// This may be reduced with the above alias to c\d()
new a\b\c\d();

// This may be reduced to c\d\e\f
new a\b\c\d\e\f();

// This may be reduced to c()
new a\b\c();

// This may be reduced to D
echo a\b\c\D;

// This may be reduced to D
a\b\c\foo();

// This can't be reduced : it is an absolute name
\a\b\c\foo();

// This can't be reduced : it is no an alias nor a prefix
a\b\d\foo();

?>

9.140.1. Suggestions

  • Use all your aliases so as to make the code shorter and more readable
  • Add new aliases for missing path
  • Make class names absolute and drop the aliases
Short name Namespaces/CouldUseAlias
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.141. Could Use Compact

Compact() turns a group of variables into an array. It may be used to simplify expressions.

<?php

$a = 1;
$b = 2;

// Compact call
$array = compact('a', 'b');

$array === [1, 2];

// Detailing all the keys and their value
$array = ['a' => $a, 'b' => $b];

?>

Note that compact accepts any string, and any undefined variable is not set, without a warning.

See also compact.

9.141.1. Suggestions

  • Replace the array() call with a compact() call.
Short name Structures/CouldUseCompact
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)
Examples WordPress

9.142. Could Use Promoted Properties

Promoted properties reduce PHP code at __construct() time. This feature is available in PHP 8.0.

<?php

class x {
    function __construct($a, $b) {
        // $a argument may be promoted to property $c
        $this->c = $a;

        // $b argument cannot be upgraded to property, as it is updated.
        // Move the addition to the new call, or keep the syntax below
        $this->d = $b + 2;
    }
}

?>

See also PHP 8: Constructor property promotion and PHP RFC: Constructor Property Promotion.

9.142.1. Suggestions

  • Update the constructor syntax, and remove the property specification.
Short name Php/CouldUsePromotedProperties
Rulesets Suggestions
Php Version 8.0+
Severity Minor
Time To Fix Quick (30 mins)

9.143. Could Use Short Assignation

Use short assignment operator, to speed up code, and keep syntax clear.

Some operators, like * or +, have a compact and fast ‘do-and-assign’ version. They looks like a compacted version for = and the operator. This syntax is good for readability, and saves some memory in the process.

Depending on the operator, not all permutations of arguments are possible.

Addition and short assignation of addition have a different set of features when applied to arrays. Do not exchange one another in that case.

<?php

$a = 10 + $a;
$a += 10;

$b = $b - 1;
$b -= 1;

$c = $c * 2;
$c *= 2;

$d = $d / 3;
$d /= 3;

$e = $e % 4;
$e %= 4;

$f = $f | 5;
$f |= 5;

$g = $g & 6;
$g &= 6;

$h = $h ^ 7;
$h ^= 7;

$i = $i >> 8;
$i >>= 8;

$j = $j << 9;
$j <<= 9;

// PHP 7.4 and more recent
$l = $l ?? 'value';
$l ??= 'value';

?>

Short operators are faster than the extended version, though it is a micro-optimization.

See also Assignation Operators.

9.143.1. Suggestions

  • Change the expression to use the short assignation
Short name Structures/CouldUseShortAssignation
Rulesets Analyze, Performances, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP use-short-assignations
Examples ChurchCRM, Thelia

9.144. Could Use Try

Some commands may raise exceptions. It is recommended to use the try/catch block to intercept those exceptions, and process them.

  • / : DivisionByZeroError
  • % : DivisionByZeroError
  • intdiv() : DivisionByZeroError
  • << : ArithmeticError
  • >> : ArithmeticError
  • Phar\:\:mungserver : PharException
  • Phar\:\:webphar : PharException

See also Predefined Exceptions, PharException.

9.144.1. Suggestions

  • Add a try/catch clause around those commands
  • Add a check on the values used with those operator : for example, check a dividend is not 0, or a bitshift is not negative
Short name Exceptions/CouldUseTry
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)
Precision High
Examples Mautic

9.145. Could Use __DIR__

Use __DIR__ constant to access the current file’s parent directory.

Avoid using dirname() on __FILE__.

<?php

// Better way
$fp = fopen(__DIR__.'/myfile.txt', 'r');

// compatible, but slow way
$fp = fopen(dirname(__FILE__).'/myfile.txt', 'r');

// Since PHP 5.3
assert(dirname(__FILE__) == __DIR__);

?>

__DIR__ has been introduced in PHP 5.3.0.

See also Magic Constants.

9.145.1. Suggestions

  • Use __DIR__ instead of dirname(__FILE__);
Short name Structures/CouldUseDir
Rulesets Analyze, Suggestions, php-cs-fixable, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples Woocommerce, Piwigo

9.146. Could Use array_fill_keys

array_fill_keys() is a native PHP function that creates an array from keys. It gets the list of keys, and a constant value to assign to each keys.

This is twice faster than doing the same with a loop.

Note that is possible to use an object as initializing value : every element of the final array will be pointing to the same value. And, also, using an object as initializing value means that the same object will be used for each key : the object will not be cloned for each value.

<?php

$array = range('a', 'z');

// Fast way to build the array
$b = array_fill_keys($a, 0);

// Fast way to build the array, but every element will be the same object
$b = array_fill_keys($a, new Stdclass());

// Slow way to build the array
foreach($array as $a) {
    $b[$a] = 0;
}

// Setting everything to null, slowly
$array = array_map(function() {}, $array);

?>

See also array_fill_keys.

9.146.1. Suggestions

  • Use array_fill_keys()
Short name Structures/CouldUseArrayFillKeys
Rulesets Suggestions
Severity Minor
Time To Fix Slow (1 hour)
Examples ChurchCRM, PhpIPAM

9.147. Could Use array_unique

Use array_unique() to collect unique elements from an array.

Always try to use native PHP functions, instead of rebuilding them with custom PHP code.

<?php

    $unique = array();
    foreach ($array as $b) {
        if (!in_array($b, $unique)) {
            /*  May be more code */
            $unique[] = $b;
        }
    }
?>

See also array_unique.

9.147.1. Suggestions

  • Turn the foreach() and its condition into a call to array_unique()
  • Extract the condition from the foreach() and add a separate call to array_unique()
Short name Structures/CouldUseArrayUnique
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)
Examples Dolibarr, OpenEMR

9.148. Could Use self

self keyword refers to the current class, or any of its parents. Using it is just as fast as the full class name, it is as readable and it is will not be changed upon class or namespace change.

It is also routinely used in traits : there, self represents the class in which the trait is used, or the trait itself.

<?php

class x {
    const FOO = 1;

    public function bar() {
        return self::FOO;
// same as return x::FOO;
    }
}

?>

See also Scope Resolution Operator (::).

9.148.1. Suggestions

  • replace the explicit name with self
Short name Classes/ShouldUseSelf
Rulesets Analyze, Suggestions, ClassReview
Severity Minor
Time To Fix Instant (5 mins)
Examples WordPress, LiveZilla

9.149. Could Use str_repeat()

Use str_repeat() or str_pad() instead of making a loop.

Making a loop to repeat the same concatenation is actually much longer than using str_repeat(). As soon as the loop repeats more than twice, str_repeat() is much faster. With arrays of 30, the difference is significant, though the whole operation is short by itself.

<?php

// This adds 7 'e' to $x
$x .= str_repeat('e', 7);

// This is the same as above,
for($a = 3; $a < 10; ++$a) {
    $x .= 'e';
}

// here, $default must contains 7 elements to be equivalent to the previous code
foreach($default as $c) {
    $x .= 'e';
}

?>

9.149.1. Suggestions

  • Use strrepeat() whenever possible
Short name Structures/CouldUseStrrepeat
Rulesets Analyze, Top10, CI-checks
Severity Minor
Time To Fix Slow (1 hour)
Precision Very high
Examples Zencart

9.150. Crc32() Might Be Negative

crc32() may return a negative number, on 32 bits platforms.

According to the manual : Because PHP’s integer type is signed many CRC32 checksums will result in negative integers on 32 bits platforms. On 64 bits installations, all crc32() results will be positive integers though.

<?php

// display the checksum with %u, to make it unsigned
echo sprintf('%u', crc32($str));

// turn the checksum into an unsigned hexadecimal
echo dechex(crc32($str));

// avoid concatenating crc32 to a string, as it may be negative on 32bits platforms
echo 'prefix'.crc32($str);

?>

See also crc32().

Short name Php/Crc32MightBeNegative
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)

9.151. Cyclic References

Avoid cyclic references.

Cyclic references happen when an object points to another object, which reciprocate. This is particularly possible with classes, when the child class has to keep a reference to the parent class.

<?php

class a {
    private $p = null;

    function foo() {
        $this->p = new b();
        // the current class is stored in the child class
        $this->p->m($this);
    }
}

class b {
    private $pb = null;

    function n($a) {
        // the current class keeps a link to its parent
        $this->pb = $a;
    }
}
?>

Cyclic references, or circular references, are memory intensive : only the garbage collector can understand when they may be flushed from memory, which is a costly operation. On the other hand, in an acyclic reference code, the reference counter will know immediately know that an object is free or not.

See also About circular references in PHP and A Journey to find a memory leak.

9.151.1. Suggestions

  • Use a different object when calling the child objects.
  • Refactor your code to avoid the cyclic reference.
Short name Classes/CyclicReferences
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.152. Dangling Array References

Always unset a referenced-variable used in a loop.

It is highly recommended to unset blind variables when they are set up as references after a loop.

<?php

$array = array(1,2,3,4);

foreach($array as &$a) {
    $a += 1;
}
// This only unset the reference, not the value
unset($a);


// Dangling array problem
foreach($array as &$a) {
    $a += 1;
}
//$array === array(3,4,5,6);

// This does nothing (apparently)
// $a is already a reference, even if it doesn't show here.
foreach($array as $a) {}
//$array === array(3,4,5,5);

?>

When omitting this step, the next loop that will also require this variable will deal with garbage values, and produce unexpected results.

See also : No Dangling Reference, PHP foreach pass-by-reference: Do it right, or better not at all, How does PHP ‘foreach’ actually work?, References and foreach.

9.152.1. Suggestions

  • Avoid using the reference altogether : sometimes, the reference is not needed.
  • Add unset() right after the loop, to avoid reusing the reference.
Short name Structures/DanglingArrayReferences
Rulesets Analyze, Top10, CI-checks
Severity Major
Time To Fix Instant (5 mins)
ClearPHP no-dangling-reference
Examples Typo3, SugarCrm

9.153. Deep Definitions

Structures, such as functions, classes, interfaces, traits, etc. may be defined anywhere in the code, including inside functions. This is legit code for PHP.

Since the availability of autoload, with spl_register_autoload(), there is no need for that kind of code. Structures should be defined, and accessible to the autoloading. Inclusions and deep definitions should be avoided, as they compel code to load some definitions, while autoloading will only load them if needed.

<?php

class X {
    function init() {
        // myFunction is defined when and only if X::init() is called.
        if (!function_exists('myFunction'){
            function myFunction($a) {
                return $a + 1;
            }
        })
    }
}

?>

Functions are excluded from autoload, but shall be gathered in libraries, and not hidden inside other code.

Constants definitions are tolerated inside functions : they may be used for avoiding repeat, or noting the usage of such function.

Definitions inside a if/then statement, that include PHP version check are accepted here.

See also Autoloading Classes.

9.153.1. Suggestions

  • Move function definitions to the global space : outside structures, and method.
Short name Functions/DeepDefinitions
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)
Examples Dolphin

9.154. Define With Array

PHP 7.0 has the ability to define an array as a constant, using the define() native call. This was not possible until that version, only with the const keyword.

<?php

//Defining an array as a constant
define('MY_PRIMES', [2, 3, 5, 7, 11]);

?>
Short name Php/DefineWithArray
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and more recent
Severity Critical
Time To Fix Slow (1 hour)

9.155. Dependant Abstract Classes

Abstract classes should be autonomous. It is recommended to avoid depending on methods, constant or properties that should be made available in inheriting classes, without explicitly abstracting them.

The following abstract classes make usage of constant, methods and properties, static or not, that are not defined in the class. This means the inheriting classes must provide those constants, methods and properties, but there is no way to enforce this.

This may also lead to dead code : when the abstract class is removed, the host class have unused properties and methods.

<?php

// autonomous abstract class : all it needs is within the class
abstract class c {
    private $p = 0;

    function foo() {
        return ++$this->p;
    }
}

// dependant abstract class : the inheriting classes needs to provide some properties or methods
abstract class c2 {
    function foo() {
        // $p must be provided by the extending class
        return ++$this->p;
    }
}

class c3 extends c2 {
    private $p = 0;
}
?>

See also Dependant Trait.

9.155.1. Suggestions

  • Make the class only use its own resources
  • Split the class in autonomous classes
  • Add local property definitions to make the class independent
Short name Classes/DependantAbstractClass
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.156. Dependant Trait

Traits should be autonomous. It is recommended to avoid depending on methods or properties that should be in the using class.

The following traits make usage of methods and properties, static or not, that are not defined in the trait. This means the host class must provide those methods and properties, but there is no way to enforce this.

This may also lead to dead code : when the trait is removed, the host class have unused properties and methods.

<?php

// autonomous trait : all it needs is within the trait
trait t {
    private $p = 0;

    function foo() {
        return ++$this->p;
    }
}

// dependant trait : the host class needs to provide some properties or methods
trait t2 {
    function foo() {
        return ++$this->p;
    }
}

class x {
    use t2;

    private $p = 0;
}
?>

See also Dependant Abstract Classes.

9.156.1. Suggestions

  • Add local property definitions to make the trait independent
  • Make the trait only use its own resources
  • Split the trait in autonomous traits
Short name Traits/DependantTrait
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples Zencart

9.157. Deprecated Functions

The following functions are deprecated. It is recommended to stop using them now and replace them with a durable equivalent.

Note that these functions may be still usable : they generate warning that help tracking their usage in the log. To eradicate their usage, watch the logs, and update any deprecated warning. This way, the code won’t be stuck when the function is actually removed from PHP.

<?php

// This is the current function
list($day, $month, $year) = explode('/', '08/06/1995');

// This is deprecated
list($day, $month, $year) = split('/', '08/06/1995');

?>

9.157.1. Suggestions

  • Replace those deprecated with modern syntax
  • Stop using deprecated syntax
Short name Php/Deprecated
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-deprecated
Examples Dolphin

9.158. Dereferencing String And Arrays

PHP allows the direct dereferencing of strings and arrays.

This was added in PHP 5.5. There is no need anymore for an intermediate variable between a string and array (or any expression generating such value) and accessing an index.

<?php
$x = array(4,5,6);
$y = $x[2] ; // is 6

May be replaced by
$y = array(4,5,6)[2];
$y = [4,5,6][2];
?>
Short name Structures/DereferencingAS
Rulesets CompatibilityPHP53, CompatibilityPHP54
Php Version With PHP 5.3 and older
Severity Major
Time To Fix Quick (30 mins)

9.159. Detect Current Class

Detecting the current class should be done with self::class or static::class operator.

__CLASS__ may be replaced by self\:\:class. get_called_class() may be replaced by static\:\:class.

__CLASS__ and get_called_class() are set to be deprecated in PHP 7.4.

<?php

class X {
    function foo() {
        echo __CLASS__.\n;          // X
        echo self::class.\n;        // X

        echo get_called_class().\n;  // Y
        echo static::class.\n;       // Y
    }
}

class Y extends X {}

$y = new Y();
$y->foo();

?>

See also PHP RFC: Deprecations for PHP 7.4.

9.159.1. Suggestions

  • Use the self::class operator to detect the current class name, instead of __CLASS__ and get_class().
  • Use the static::class operator to detect the current called class name, instead of get_called_class().
Short name Php/DetectCurrentClass
Rulesets Suggestions, CompatibilityPHP74
Php Version With PHP 8.0 and older
Precision Very high

9.160. Different Argument Counts

Two methods with the same name shall have the same number of compulsory argument. PHP accepts different number of arguments between two methods, if the extra arguments have default values. Basically, they shall be called interchangeably with the same number of arguments.

The number of compulsory arguments is often mistaken for the same number of arguments. When this is the case, it leads to confusion between the two signatures. It will also create more difficulties when refactoring the signature.

While this code is legit, it is recommended to check if the two signatures could be synchronized, and reduce future surprises.

<?php

class x {
    function foo($a ) {}
}

class y extends x {
    // This method is compatible with the above, its signature is different
    function foo($a, $b = 1) {}
}

?>

9.160.1. Suggestions

  • Extract the extra arguments into other methods
  • Remove the extra arguments
  • Add the extra arguments to all the signatures
Short name Classes/DifferentArgumentCounts
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.161. Direct Call To __clone()

Direct call to magic method __clone() was forbidden. It is allowed since PHP 7.0.

From the RFC : Doing calls like $obj->`__clone( <https://www.php.net/manual/en/language.oop5.magic.php>`_ ) is now allowed. This was the only magic method that had a compile-time check preventing some calls to it, which doesn't make sense. If we allow all other magic methods to be called, there's no reason to forbid this one.

<?php

    class Foo {
        function __clone() {}
    }

    $a = new Foo;
    $a->__clone();
?>

See also Directly calling `__clone is allowed <https://wiki.php.net/rfc/abstract_syntax_tree#directly_calling_clone_is_allowed>`_.

9.161.1. Suggestions

  • Use the clone operator to call the __clone magic method
Short name Php/DirectCallToClone
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and more recent
Severity Critical
Time To Fix Slow (1 hour)

9.162. Direct Injection

The following code act directly upon PHP incoming variables like $_GET and $_POST. This makes those snippets very unsafe.

<?php

// Direct injection
echo Hello.$_GET['user']., welcome.;

// less direct injection
foo($_GET['user']);
function foo($user) {
    echo Hello.$user., welcome.;
}

?>

See also Cross-Site Scripting (XSS)

9.162.1. Suggestions

  • Validate input : make sure the incoming data are what you expect from them.
  • Escape output : prepare outgoing data for the next system to use.
Short name Security/DirectInjection
Rulesets Security
Severity Major
Time To Fix Quick (30 mins)

9.163. Directly Use File

Some PHP functions have a close cousin that work directly on files : use them. This is faster and less code to write.

<?php

// Good way
$file_hash = hash_file('sha512', 'example.txt');

// Slow way
$file_hash = hash('sha512', file_get_contents('example.txt'));

?>

See also hash_file.

9.163.1. Suggestions

  • Use the _file() version of those functions
Short name Structures/DirectlyUseFile
Rulesets Suggestions
Severity Minor
Time To Fix Instant (5 mins)

9.164. Disconnected Classes

One class is extending the other, but they do not use any features from one another. Basically, those two classes are using extends, but they are completely independent and may be separated.

When using the ‘extends’ keyword, the newly created classes are now acting together and making one. This should be visible in calls from one class to the other, or simply by property usage : they can’t live without each other.

On the other hand, two completely independent classes that are merged, although they should be kept separated.

<?php

class A {
    private $pa = 1;

    function fooA() {
        $this->pa = 2;
    }
}

// class B and Class A are totally independent
class B extends A {
    private $pb = 1;

    function fooB() {
        $this->pb = 2;
    }
}


// class C makes use of class A : it is dependent on the parent class
class C extends A {
    private $pc = 1;

    function fooB() {
        $this->pc = 2 + $this->fooA();
    }
}
?>

9.164.1. Suggestions

  • Remove the extension
  • Make actual usage of the classes, at least from one of them
Short name Classes/DisconnectedClasses
Rulesets ClassReview
Severity Minor
Time To Fix Slow (1 hour)
Examples WordPress

9.165. Do In Base

Use SQL expression to compute aggregates.

<?php

// Efficient way
$res = $db->query('SELECT sum(e) AS sumE FROM table WHERE condition');

// The sum is already done
$row = $res->fetchArray();
$c += $row['sumE'];

// Slow way
$res = $db->query('SELECT e FROM table WHERE condition');

// This aggregates the column e in a slow way
while($row = $res->fetchArray()) {
    $c += $row['e'];
}

?>

9.165.1. Suggestions

  • Rework the query to move the calculations in the database
Short name Performances/DoInBase
Rulesets Performances
Severity Major
Time To Fix Quick (30 mins)

9.166. Don’t Be Too Manual

Adapt the examples from the PHP manual to your code. Don’t reuse directly the same names in your code : be more specific about what to expect in those variables.

<?php

// Search for phone numbers in a text
preg_match_all('/((\d{3})-(\d{3})-(\d{4}))/', $string, $phoneNumber);

// Search for phone numbers in a text
preg_match_all('/(\d{3})-(\d{3})-(\d{4})/', $string, $matches);

?>

9.166.1. Suggestions

  • Use precise name with your variables
Short name Structures/DontBeTooManual
Rulesets Coding Conventions
Severity Minor
Time To Fix Quick (30 mins)

9.167. Don’t Change Incomings

PHP hands over a lot of information using special variables like $_GET, $_POST, etc… Modifying those variables and those values inside variables means that the original content is lost, while it will still look like raw data, and, as such, will be untrustworthy.

<?php

// filtering and keeping the incoming value.
$_DATA'id'] = (int) $_GET['id'];

// filtering and changing the incoming value.
$_GET['id'] = strtolower($_GET['id']);

?>

It is recommended to put the modified values in another variable, and keep the original one intact.

Short name Structures/NoChangeIncomingVariables
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)

9.168. Don’t Echo Error

It is recommended to avoid displaying error messages directly to the browser.

PHP’s uses the display_errors directive to control display of errors to the browser. This must be kept to off when in production.

<?php

// Inside a 'or' test
mysql_connect('localhost', $user, $pass) or die(mysql_error());

// Inside a if test
$result = pg_query( $db, $query );
if( !$result )
{
     echo Erreur SQL: . pg_error();
     exit;
}

// Changing PHP configuration
ini_set('display_errors', 1);
// This is also a security error : 'false' means actually true.
ini_set('display_errors', 'false');

?>

Error messages should be logged, but not displayed.

See also Error reporting and List of php.ini directives.

9.168.1. Suggestions

  • Remove any echo, print, printf() call built with error messages from an exception, or external source.
Short name Security/DontEchoError
Rulesets Analyze, Security, CI-checks
Severity Critical
Time To Fix Instant (5 mins)
Examples ChurchCRM, Phpdocumentor

9.169. Don’t Loop On Yield

Use yield from, instead of looping on a generator with yield.

yield from delegate the yielding to another generator, and keep calling that generator until it is finished. It also works with implicit generator datastructure, like arrays.

<?php

function generator() {
    for($i = 0; $i < 10; ++$i) {
        yield $i;
    }
}

function delegatingGenerator() {
    yield from generator();
}

// Too much code here
function generator2() {
    foreach(generator() as $g) {
        yield $g;
    }
}

?>

There is a performance gain when delegating, over looping manually on the generator. You may even consider writing the loop to store all values in an array, then yield from the array.

See also Generator delegation via yield from.

9.169.1. Suggestions

  • Use yield from instead of the whole foreach() loop
Short name Structures/DontLoopOnYield
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)
Examples Dolibarr, Tikiwiki

9.170. Don’t Pollute Global Space

Avoid creating definitions in the global name space.

The global namespace is the default namespace, where all functions, classes, constants, traits and interfaces live. The global namespace is also known as the root namespace.

In particular, PHP native classes usually live in that namespace. By creating functions in that namespace, the code may encounter naming conflict, when the PHP group decides to use a name that the code also uses. This already happened in PHP version 5.1.1, where a Date native class was introduced, and had to be disabled in the following minor version.

Nowadays, conflicts appear between components, which claim the same name.

See also Using namespaces: fallback to global function/constant.

9.170.1. Suggestions

  • Create a namespace for your code, and store your definition there.
Short name Php/DontPolluteGlobalSpace
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.171. Don’t Read And Write In One Expression

Avoid giving value and using it at the same time, in one expression. This is an undefined behavior of PHP, and may change without warning.

One of those changes happens between PHP 7.2 and 7.3 :

<?php

$arr = [1];
$ref =& $arr[0];
var_dump($arr[0] + ($arr[0] = 2));
// PHP 7.2: int(4)
// PHP 7.3: int(3)

?>

See also UPGRADING 7.3.

9.171.1. Suggestions

  • Split the expression in two separate expressions
Short name Structures/DontReadAndWriteInOneExpression
Rulesets Analyze, CompatibilityPHP73, CompatibilityPHP74
Severity Critical
Time To Fix Quick (30 mins)

9.172. Don’t Send $this In Constructor

Don’t use $this as an argument while in the __construct(). Until the constructor is finished, the object is not finished, and may be in an unstable state. Providing it to another code may lead to error.

This is true when the receiving structure puts the incoming object immediately to work, and don’t store it for later use.

<?php

// $this is only provided when Foo is constructed
class Foo {
    private $bar = null;
    private $data = array();

    static public function build($data) {
        $foo = new Foo($data);
        // Can't build in one call. Must make it separate.
        $foo->finalize();
    }

    private function __construct($data) {
        // $this is provided too early
        $this->data = $data;
    }

    function finalize() {
        $this->bar = new Bar($this);
    }
}

// $this is provided too early, leading to error in Bar
class Foo2 extends Foo {
    private $bar = null;
    private $data = array();

    function __construct($data) {
        // $this is provided too early
        $this->bar = new Bar($this);
        $this->data = $data;
    }
}

class Bar {
    function __construct(Foo $foo) {
        // the cache is now initialized with a wrong
        $this->cache = $foo->getIt();
    }
}

?>

See also Don’t pass this out of a constructor.

9.172.1. Suggestions

  • Finish the constructor first, then call an external object.
  • Sending $this should be made accessible in a separate method, so external objects may call it.
  • Sending the current may be the responsibility of the method creating the object.
Short name Classes/DontSendThisInConstructor
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples Woocommerce, Contao

9.173. Don’t Unset Properties

Avoid unsetting properties. They would go undefined, and raise more warnings.

When getting rid of a property, assign it to null. This keeps the property in the object, yet allows existence check without errors.

<?php

class Foo {
    public $a = 1;
}

$a = new Foo();

var_dump((array) $a) ;
// la propriété est reportée, et null
// ['a' => null]

unset($a->a);

var_dump((array) $a) ;
//Empty []

// Check if a property exists
var_dump($a->b === null);

// Same result as above, but with a warning
var_dump($a->c === null);

?>

This analysis works on properties and static properties. It also reports magic properties being unset.

Thanks for Benoit Burnichon for the original idea.

9.173.1. Suggestions

  • Never unset properties : set it to null or its default value instead
  • Make the property an array, and set/unset its index
Short name Classes/DontUnsetProperties
Rulesets Analyze, Top10, php-cs-fixable, CI-checks
Severity Major
Time To Fix Slow (1 hour)
Examples Vanilla, Typo3

9.174. Dont Change The Blind Var

When using a foreach(), the blind variables hold a copy of the original value. It is confusing to modify them, as it seems that the original value may be changed.

When actually changing the original value, use the reference in the foreach definition to make it obvious, and save the final reassignation.

When the value has to be prepared before usage, then save the filtered value in a separate variable. This makes the clean value obvious, and preserve the original value for a future usage.

<?php

// $bar is duplicated and kept
$foo = [1, 2, 3];
foreach($foo as $bar) {
    // $bar is updated but its original value is kept
    $nextBar = $bar + 1;
    print $bar . ' => ' . ($nextBar) . PHP_EOL;
    foobar($nextBar);
}

// $bar is updated and lost
$foo = [1, 2, 3];
foreach($foo as $bar) {
    // $bar is updated but its final value is lost
    print $bar . ' => ' . (++$bar) . PHP_EOL;
    // Now that $bar is reused, it is easy to confuse its value
    foobar($bar);
}

// $bar is updated and kept
$foo = [1, 2, 3];
foreach($foo as &$bar) {
    // $bar is updated and keept
    print $bar . ' => ' . (++$bar) . PHP_EOL;
    foobar($bar);
}

?>
Short name Structures/DontChangeBlindKey
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.175. Dont Collect Void

When a method returns void, there is no need to collect the result. The collected value will actually be null.

<?php

function foo() : void {
    // doSomething()
}

// This is useless
$result = foo();

// This is useless. It looks like this is a left over from code refactoring
echo foo();

?>

9.175.1. Suggestions

  • Move the call to the function to its own expression with a semi-colon.
  • Remove assignation of the result of such calls.
Short name Functions/DontUseVoid
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Precision Very high

9.176. Dont Compare Typed Boolean

There is no need to compare explicitly a function call to a boolean, when the definition has a boolean return typehint.

The analysis checks for equality and identity comparisons. It doesn’t check for the not operator usage.

<?php

// Sufficient check
if (foo()) {
    doSomething();
}

// Superfluous check
if (foo() === true) {
    doSomething();
}

function foo() : bool {}

?>

9.176.1. Suggestions

  • Simplify the code and make it short
Short name Structures/DontCompareTypedBoolean
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.177. Dont Mix ++

++ operators, pre and post, have two distinct behaviors, and should be used separately.

When mixed in a larger expression, they are difficult to read, and may lead to unwanted behaviors.

<?php

    // Clear and defined behavior
    $i++;
    $a[$i] = $i;

    // The index is also incremented, as it is used AFTP the incrementation
    // With $i = 2; $a is array(3 => 3)
    $a[$i] = ++$i;

    // $i is actually modified twice
    $i = --$i + 1;
?>

See also EXP30-C. Do not depend on the order of evaluation for side effects.

9.177.1. Suggestions

  • Extract the increment from the expression, and put it on a separate line.
Short name Structures/DontMixPlusPlus
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)
Examples Contao, Typo3

9.178. Double Assignation

This happens when a container (variable, property, array index) is assigned with values twice in a row. One of them is probably a debug instruction, that was forgotten.

<?php

// Normal assignation
$a = 1;

// Double assignation
$b = 2;
$b = 3;

?>
Short name Structures/DoubleAssignation
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.179. Double Instructions

Twice the same call in a row. This is worth a check.

<?php

// repetition of the same command, with the same effect each time.
$a = array_merge($b, $c);
$a = array_merge($b, $c);

// false positive : commands are identical, but the effect is compounded
$a = array_merge($a, $c);
$a = array_merge($a, $c);

?>

9.179.1. Suggestions

  • Remove double work
  • Avoid repetition by using loops, variadic or quantifiers (dirname($path, 2))
Short name Structures/DoubleInstruction
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)

9.180. Double Object Assignation

Make sure that assigning the same object to two variables is the intended purpose.

<?php

// $x and $y are the same object, as they both hold a reference to the same object.
// This means that changing $x, will also change $y.
$x = $y = new Z();

// $a and $b are distinct values, by default
$a = $b = 1;

?>

9.180.1. Suggestions

Short name Structures/DoubleObjectAssignation
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.181. Double array_flip()

Avoid double array_flip() to gain speed. While array_flip() alone is usually useful, a double call to array_flip() is made to make values and keys unique.

<?php

// without array_flip
function foo($array, $value) {
    $key = array_search($array, $value);

    if ($key !== false) {
        unset($array[$key]);
    }

    return $array;
}

// double array_flip
// array_flip() usage means that $array's values are all unique
function foo($array, $value) {
    $flipped = array_flip($value);
    unset($flipped[$value]);
    return array_flip($flipped);
}

?>

9.181.1. Suggestions

  • use array_unique() or array_count_values
  • use array_flip() once, and let PHP garbage collect it later
  • Keep the original values in a separate variable
Short name Performances/DoubleArrayFlip
Rulesets Performances
Severity Major
Time To Fix Quick (30 mins)
Examples NextCloud

9.182. Drop Else After Return

Avoid else clause when the then clause returns, but not the else. And vice-versa.

This way, the else block disappears, and is now the main sequence of the function.

This is also true if else has a return, and then not. When doing so, don’t forget to reverse the condition.

<?php

// drop the else
if ($a) {
    return $a;
} else {
    doSomething();
}

// drop the then
if ($b) {
    doSomething();
} else {
    return $a;
}

// return in else and then
if ($a3) {
    return $a;
} else {
    $b = doSomething();
    return $b;
}

?>

9.182.1. Suggestions

  • Remove the else clause and move its code to the main part of the method
Short name Structures/DropElseAfterReturn
Rulesets Analyze, Suggestions, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.183. Drop Substr Last Arg

Substr() works till the end of the string when the last argument is omitted. There is no need to calculate string size to make this work.

<?php

$string = 'abcdef';

// Extract the end of the string
$cde = substr($string, 2);

// Too much work
$cde = substr($string, 2, strlen($string));

?>

See also substr.

9.183.1. Suggestions

  • Use negative length
  • Omit the last argument to get the string till its end
Short name Structures/SubstrLastArg
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)
Examples SuiteCrm, Tine20

9.184. Duplicate Literal

Report literals that are repeated across the code. The minimum replication is 5, and is configurable with maxDuplicate.

Repeated literals should be considered a prime candidate for constants.

Integer, reals and strings are considered here. Boolean, Null and Arrays are omitted. 0, 1, 2, 10 and the empty string are all omitted, as too common.

<?php
    // array index are omitted
    $x[3] = 'b';

    // constanst are omitted
    const X = 11;
    define('Y', 'string')

    // 0, 1, 2, 10 are omitted
    $x = 0;

?>

9.184.1. Suggestions

  • Create a constant and use it in place of the literal
  • Create a class constant and use it in place of the literal
Name Default Type Description
minDuplicate 15 integer Minimal number of duplication before the literal is reported.
Short name Type/DuplicateLiteral
Rulesets Semantics
Severity Minor
Time To Fix Quick (30 mins)

9.185. Dynamic Library Loading

Loading a variable dynamically requires a lot of care in the preparation of the library name.

In case of injection in the variable, the dynamic loading of a library gives a lot of power to an intruder.

<?php

    // dynamically loading a library
     dl($library. PHP_SHLIB_SUFFIX);

    // dynamically loading ext/vips
     dl('vips.' . PHP_SHLIB_SUFFIX);

    // static loading ext/vips (unix only)
     dl('vips.so');

?>

See also dl.

9.185.1. Suggestions

  • Use a switch structure, to make the dl() calls static.
  • Avoid using dl() and make the needed extension always available in PHP binary.
Short name Security/DynamicDl
Rulesets Security
Severity Major
Time To Fix Slow (1 hour)

9.186. Echo Or Print

Echo and print have the same functional use. <?= and printf() are also considered in this analysis.

There seems to be a choice that is not enforced : one form is dominant, (> 90%) while the others are rare.

The analyzed code has less than 10% of one of the three : for consistency reasons, it is recommended to make them all the same.

It happens that print, echo or <?= are used depending on coding style and files. One file may be consistently using print, while the others are all using echo.

<?php

echo 'a';
echo 'b';
echo 'c';
echo 'd';
echo 'e';
echo 'f';
echo 'g';
echo 'h';
echo 'i';
echo 'j';
echo 'k';

// This should probably be written 'echo';
print 'l';

?>
Short name Structures/EchoPrintConsistance
Rulesets Coding Conventions
Severity Minor
Time To Fix Quick (30 mins)

9.187. Echo With Concat

Optimize your echo’s by not concatenating at echo time, but serving all argument separated. This will save PHP a memory copy.

If values, literals and variables, are small enough, this won’t have visible impact. Otherwise, this is less work and less memory waste.

<?php
  echo $a, ' b ', $c;
?>

instead of

<?php
  echo  $a . ' b ' . $c;
  echo $a b $c;
?>

9.187.1. Suggestions

  • Turn the concatenation into a list of argument, by replacing the dots by commas.
Short name Structures/EchoWithConcat
Rulesets Performances, Analyze, Suggestions
Severity Minor
Time To Fix Quick (30 mins)
ClearPHP no-unnecessary-string-concatenation
Examples Phpdocumentor, TeamPass

9.188. Ellipsis Usage

Usage of the ellipsis keyword. The keyword is three dots : . It is also named variadic or splat operator.

It may be in function definitions, either in functioncalls.

allows for packing or unpacking arguments into an array.

<?php

$args = [1, 2, 3];
foo(...$args);
// Identical to foo(1,2,3);

function bar(...$a) {
    // Identical to : $a = func_get_args();
}
?>

See also PHP RFC: Syntax for variadic functions, PHP 5.6 and the Splat Operator, and Variable-length argument lists.

Short name Php/EllipsisUsage
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55
Php Version With PHP 5.6 and more recent
Severity Major
Time To Fix Slow (1 hour)

9.189. Else If Versus Elseif

Always use elseif instead of else and if.

“The keyword elseif SHOULD be used instead of else if so that all control keywords look like single words”. Quoted from the PHP-FIG documentation

<?php

// Using elseif
if ($a == 1) { doSomething(); }
elseif ($a == 2) { doSomethingElseIf(); }
else { doSomethingElse(); }

// Using else if
if ($a == 1) { doSomething(); }
else if ($a == 2) { doSomethingElseIf(); }
else { doSomethingElse(); }

// Using else if, no {}
if ($a == 1)  doSomething();
else if ($a == 2) doSomethingElseIf();
else  doSomethingElse();

?>

See also elseif/else if.

9.189.1. Suggestions

  • Merge else and if into elseif
  • Turn the else expression into a block, and have more than the second if in this block
  • Turn the if / else if / else into a switch structure
Short name Structures/ElseIfElseif
Rulesets Analyze, php-cs-fixable, Rector, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples TeamPass, Phpdocumentor

9.190. Empty Blocks

Full empty block, part of a control structures.

It is recommended to remove those blocks, so as to reduce confusion in the code.

<?php

foreach($foo as $bar) ; // This block seems erroneous
    $foobar++;

if ($a === $b) {
    doSomething();
} else {
    // Empty block. Remove this
}

// Blocks containing only empty expressions are also detected
for($i = 0; $i < 10; $i++) {
    ;
}

// Although namespaces are not control structures, they are reported here
namespace A;
namespace B;

?>

9.190.1. Suggestions

  • Fill the block with a command
  • Fill the block with a comment that explain the situation
  • Remove the block and its commanding operator
Short name Structures/EmptyBlocks
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples Cleverstyle, PhpIPAM

9.191. Empty Classes

Classes that do no define anything at all. This is probably dead code.

Classes that are directly derived from an exception are omitted.

<?php

//Empty class
class foo extends bar {}

//Not an empty class
class foo2 extends bar {
    const FOO = 2;
}

//Not an empty class, as derived from Exception
class barException extends \Exception {}

?>

9.191.1. Suggestions

  • Remove an empty class :it is probably dead code.
  • Add some code to the class to make it concrete.
Short name Classes/EmptyClass
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples WordPress

9.192. Empty Function

Function or method whose body is empty.

Such functions or methods are rarely useful. As a bare minimum, the function should return some useful value, even if constant.

A method is considered empty when it contains nothing, or contains expressions without impact.

<?php

// classic empty function
function emptyFunction() {}

class bar {
    // classic empty method
    function emptyMethod() {}

    // classic empty function
    function emptyMethodWithParent() {}
}

class barbar extends bar {
    // NOT an empty method : it overwrites the parent method
    function emptyMethodWithParent() {}
}

?>

Methods which overwrite another methods are omitted. Methods which are the concrete version of an abstract method are considered.

9.192.1. Suggestions

  • Fill the function with actual code
  • Remove any usage of the function, then remove the function
Short name Functions/EmptyFunction
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Precision High
Examples Contao

9.193. Empty Instructions

Empty instructions are part of the code that have no instructions.

This may be trailing semi-colon or empty blocks for if-then structures.

Comments that explains the reason of the situation are not taken into account.

<?php
    $condition = 3;;;;
    if ($condition) { }
?>

9.193.1. Suggestions

  • Remove the empty lines
  • Fill the empty lines
Short name Structures/EmptyLines
Rulesets Dead code, Analyze
Severity Minor
Time To Fix Instant (5 mins)
Examples Zurmo, ThinkPHP

9.194. Empty Interfaces

Empty interfaces are a code smell. Interfaces should contains at least a method or a constant, and not be totally empty.

<?php

// an empty interface
interface empty {}

// an normal interface
interface normal {
    public function i() ;
}

// a constants interface
interface constantsOnly {
    const FOO = 1;
}

?>

See also Empty interfaces are bad practice and Blog : Are empty interfaces code smell?.

9.194.1. Suggestions

  • Remove the interface
  • Add some methods or constants to the interface
Short name Interfaces/EmptyInterface
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)

9.195. Empty List

Empty list() are not allowed anymore in PHP 7. There must be at least one variable in the list call.

<?php

//Not accepted since PHP 7.0
list() = array(1,2,3);

//Still valid PHP code
list(,$x) = array(1,2,3);

?>

9.195.1. Suggestions

  • Remove empty list() calls
Short name Php/EmptyList
Rulesets Analyze, CompatibilityPHP70
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Quick (30 mins)

9.196. Empty Namespace

Declaring a namespace in the code and not using it for structure declarations or global instructions is useless.

Using simple style :

<?php

namespace Y;

class foo {}


namespace X;
// This is useless

?>

Using bracket-style syntax :

<?php

namespace X {
    // This is useless
}

namespace Y {

    class foo {}

}

?>

9.196.1. Suggestions

  • Remove the namespace
Short name Namespaces/EmptyNamespace
Rulesets Analyze, Dead code, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP no-empty-namespace

9.197. Empty Slots In Arrays

PHP tolerates the last element of an array to be empty.

<?php
    $a = array( 1, 2, 3, );
    $b =      [ 4, 5, ];
?>
Short name Arrays/EmptySlots
Rulesets Coding Conventions
Severity Minor
Time To Fix Instant (5 mins)

9.198. Empty Traits

List of all empty trait defined in the code.

<?php

// empty trait
trait t { }

// Another empty trait
trait t2 {
    use t;
}

?>

Such traits may be reserved for future use. They may also be forgotten, and dead code.

9.198.1. Suggestions

  • Add some code to the trait
  • Remove the trait
Short name Traits/EmptyTrait
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)

9.199. Empty Try Catch

The code does try, then catch errors but do no act upon the error.

<?php

try {
    doSomething();
} catch (Throwable $e) {
    // ignore this
}

?>

At worst, the error should be logged, so as to measure the actual usage of the catch expression.

catch( Exception $e) (PHP 5) or catch(`Throwable <https://www.php.net/manual/en/class.throwable.php>`_ $e) with empty catch block should be banned. They ignore any error and proceed as if nothing happened. At worst, the event should be logged for future analysis.

See also Empty Catch Clause.

9.199.1. Suggestions

  • Add some logging in the catch
  • Add a comment to mention why the catch is empty
  • Change the exception, chain it and throw again
Short name Structures/EmptyTryCatch
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples LiveZilla, Mautic

9.200. Empty With Expression

empty() doesn’t accept expressions until PHP 5.5. Until then, it is necessary to store the result of the expression in a variable and then, test it with empty().

<?php

// PHP 5.5+ empty() usage
if (empty(strtolower($b . $c))) {
    doSomethingWithoutA();
}

// Compatible empty() usage
$a = strtolower($b . $c);
if (empty($a)) {
    doSomethingWithoutA();
}

?>

See also empty.

9.200.1. Suggestions

  • Use the compatible syntax, and store the result in a local variable before testing it with empty
Short name Structures/EmptyWithExpression
Rulesets Suggestions
Php Version With PHP 5.5 and more recent
Severity Major
Time To Fix Quick (30 mins)
Examples HuMo-Gen

9.201. Encoded Simple Letters

Some simple letters are written in escape sequence.

Usually, escape sequences are made to encode unusual characters. Using escape sequences for simple characters, like letters or numbers is suspicious.

This analysis also detects Unicode codepoint with superfluous leading zeros.

<?php

// This escape sequence makes eval hard to spot
$a = ev1l;
$a('php_info();');

// With a PHP 7.0 unicode code point sequence
$a = ev\u{000041}l;
$a('php_info();');

// With a PHP 5.0+ hexadecimal sequence
$a = ev\x41l;
$a('php_info();');

?>

9.201.1. Suggestions

  • Make all simple letter appear clearly
  • Add comments about why this code is encoded
Short name Security/EncodedLetters
Rulesets Security
Severity Minor
Time To Fix Quick (30 mins)
Examples Zurmo

9.202. Eval() Usage

Using eval() is evil.

Using eval() is bad for performances (compilation time), for caches (it won’t be compiled), and for security (if it includes external data).

<?php
    // Avoid using incoming data to build the eval() expression : any filtering error leads to PHP injection
    $mathExpression = $_GET['mathExpression'];
    $mathExpression = preg_replace('#[^0-9+\-*/\(/)]#is', '', $mathExpression); // expecting 1+2
    $literalCode = '$a = '.$mathExpression.';';
    eval($literalCode);
    echo $a;

    // If the code code given to eval() is known at compile time, it is best to put it inline
    $literalCode = 'phpinfo();';
    eval($literalCode);

?>

Most of the time, it is possible to replace the code by some standard PHP, like variable variable for accessing a variable for which you have the name. At worse, including a pregenerated file is faster and cacheable.

There are several situations where eval() is actually the only solution :

For PHP 7.0 and later, it is important to put eval() in a try..catch expression.

See also eval and The Land Where PHP Uses `eval() <https://www.exakat.io/land-where-php-uses-eval/>`_.

9.202.1. Suggestions

  • Use a dynamic feature of PHP to replace the dynamic code
  • Store the code on the disk, and use include
  • Replace create_function() with a closure!
Short name Structures/EvalUsage
Rulesets Analyze, Performances, Security
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-eval
Examples XOOPS, Mautic

9.203. Exceeding Typehint

The typehint is not fully used in the method. Some of the defined methods in the typehint are unused. A tighter typehint could be used, to avoid method pollution.

<?php

interface i {
    function i1();
    function i2();
}

interface j {
    function j1();
    function j2();
}

function foo(i $a, j $b) {
    // the i typehint is totally used
    $a->i1();
    $a->i2();

    // the i typehint is not totally used : j2() is not used.
    $b->j1();
}

?>

Tight typehint prevents the argument from doing too much. They also require more maintenance : creation of dedicated interfaces, method management to keep all typehint tight.

See also Insufficient Typehint.

9.203.1. Suggestions

  • Keep the typehint tight, do not inject more than needed.
Short name Functions/ExceedingTypehint
Rulesets ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.204. Exception Order

When catching exception, the most specialized exceptions must be in the early catch, and the most general exceptions must be in the later catch. Otherwise, the general catches intercept the exception, and the more specialized will not be read.

<?php

class A extends \Exception {}
class B extends A {}

try {
    throw new A();
}
catch(A $a1) { }
catch(B $b2 ) {
    // Never reached, as previous Catch is catching the early worm
}

?>
Short name Exceptions/AlreadyCaught
Rulesets Dead code
Examples Woocommerce

9.205. Exit() Usage

Using exit or die() <https://www.php.net/`die>`_ in the code makes the code untestable (it will break unit tests). Moreover, if there is no reason or string to display, it may take a long time to spot where the application is stuck.

<?php

// Throw an exception, that may be caught somewhere
throw new \Exception('error');

// Dying with error message.
die('error');

function foo() {
    //exiting the function but not dying
    if (somethingWrong()) {
        return true;
    }
}
?>

Try exiting the function/class with return, or throw exception that may be caught later in the code.

9.205.1. Suggestions

  • Avoid exit and die. Let the script finish.
  • Throw an exception and let it be handled before finishing
Short name Structures/ExitUsage
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-exit
Examples Traq, ThinkPHP

9.206. Exponent Usage

Usage of the ** operator or **=, to make exponents.

<?php

$eight = 2 ** 3;

$sixteen = 4;
$sixteen \*\*\= 2;

?>

See also Arithmetic Operators.

Short name Php/ExponentUsage
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55
Php Version With PHP 5.6 and more recent
Severity Major
Time To Fix Instant (5 mins)

9.207. Failed Substr Comparison

The extracted string must be of the size of the compared string.

This is also true for negative lengths.

<?php

// Possible comparison
if (substr($a, 0, 3) === 'abc') { }
if (substr($b, 4, 3) === 'abc') { }

// Always failing
if (substr($a, 0, 3) === 'ab') { }
if (substr($a, 3, -3) === 'ab') { }

// Omitted in this analysis
if (substr($a, 0, 3) !== 'ab') { }

?>

9.207.1. Suggestions

  • Fix the string
  • Fix the length of the string
  • Put the string in a constant, and use strlen() or mb_strlen()
Short name Structures/FailingSubstrComparison
Rulesets Analyze, Top10, CI-checks
Severity Major
Time To Fix Instant (5 mins)
Examples Zurmo, MediaWiki

9.208. Fetch One Row Format

When reading results with ext/Sqlite3, it is recommended to explicitly request SQLITE3_NUM or SQLITE3_ASSOC, while avoiding the default value and SQLITE3_BOTH.

<?php

$res = $database->query($query);

// Fastest version, but less readable
$row = $res->fetchArray(\SQLITE3_NUM);
// Almost the fastest version, and more readable
$row = $res->fetchArray(\SQLITE3_ASSOC);

// Default version. Quite slow
$row = $res->fetchArray();

// Worse case
$row = $res->fetchArray(\SQLITE3_BOTH);

?>

This is a micro-optimisation. The difference may be visible with 200k rows fetches, and measurable with 10k.

9.208.1. Suggestions

  • Specify the result format when reading rows from a Sqlite3 database
Short name Performances/FetchOneRowFormat
Rulesets Performances
Severity Minor
Time To Fix Instant (5 mins)

9.209. Filter To add_slashes()

FILTER_SANITIZE_MAGIC_QUOTES is deprecated. In PHP 7.4, it should be replaced with addslashes()

According to the migration RDFC : ‘Magic quotes were deprecated all the way back in PHP 5.3 and later removed in PHP 5.4. The filter extension implements a sanitization filter that mimics this behavior of magic_quotes by calling addslashes() on the input in question.’

<?php

// Deprecated way to filter input
$var = filter_input($input, FILTER_SANITIZE_MAGIC_QUOTES);

// Alternative way to filter input
$var = addslashes($input);

?>

addslashes() used to filter data while building SQL queries, to prevent injections. Nowadays, prepared queries are a better option.

See also Deprecations for PHP 7.4.

9.209.1. Suggestions

  • Replace FILTER_SANITIZE_MAGIC_QUOTES with addslashes()
  • Replace FILTER_SANITIZE_MAGIC_QUOTES with an adapted escaping system
Short name Php/FilterToAddSlashes
Rulesets CompatibilityPHP74
Severity Minor
Time To Fix Quick (30 mins)

9.210. Final Class Usage

List of all final classes being used.

final may be applied to classes and methods.

<?php
class BaseClass {
   public function test() {
       echo 'BaseClass::test() called'.PHP_EOL;
   }

   final public function moreTesting() {
       echo 'BaseClass::moreTesting() called'.PHP_EOL;
   }
}

class ChildClass extends BaseClass {
   public function moreTesting() {
       echo 'ChildClass::moreTesting() called'.PHP_EOL;
   }
}
// Results in Fatal error: Cannot override final method BaseClass::moreTesting()
?>

See also Final Keyword.

Short name Classes/Finalclass
Rulesets ClassReview, LintButWontExec

9.211. Final Methods Usage

List of all final methods being used.

final may be applied to classes and methods.

<?php
class BaseClass {
   public function test() {
       echo 'BaseClass::test() called'.PHP_EOL;
   }

   final public function moreTesting() {
       echo 'BaseClass::moreTesting() called'.PHP_EOL;
   }
}

class ChildClass extends BaseClass {
   public function moreTesting() {
       echo 'ChildClass::moreTesting() called'.PHP_EOL;
   }
}
// Results in Fatal error: Cannot override final method BaseClass::moreTesting()
?>

See also Final Keyword.

Short name Classes/Finalmethod
Rulesets LintButWontExec, ClassReview

9.212. Flexible Heredoc

Flexible syntax for Heredoc.

The new flexible syntax for heredoc and nowdoc enable the closing marker to be indented, and remove the new line requirement after the closing marker.

It was introduced in PHP 7.3.

<?php

// PHP 7.3 and newer
foo($a = <<<END

    flexible syntax
    with extra indentation

    END);

// All PHP versions
$a = <<<END

    Normal syntax

END;


?>

This syntax is backward incompatible : once adopted in the code, previous versions won’t compile it.

See also Heredoc and Flexible Heredoc and Nowdoc Syntaxes.

Short name Php/FlexibleHeredoc
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.3 and more recent
Severity Critical
Time To Fix Instant (5 mins)

9.213. Fn Argument Variable Confusion

Avoid using local variables as arrow function arguments.

When a local variable name is used as an argument’s name in an arrow function, the local variable from the original scope is not imported. They are now two distinct variables.

When the local variable is not listed as argument, it is then imported in the arrow function.

<?php

function foo() {
    $locale = 1;

    // Actually ignores the argument, and returns the local variable ``$locale``.
    $fn2 = fn ($argument) => $locale;

    // Seems similar to above, but returns the incoming argument
    $fn2 = fn ($locale) => $locale;
}

?>

See also Arrow functions.

9.213.1. Suggestions

  • Change the name of the local variable
  • Change the name of the argument
Short name Functions/FnArgumentVariableConfusion
Rulesets Analyze, Semantics
Php Version 7.4+
Severity Minor
Time To Fix Quick (30 mins)

9.214. For Using Functioncall

It is recommended to avoid functioncall in the for() statement.

<?php

// Fastest way
$nb = count($array);
for($i = 0; $i < $nb; ++$i) {
    doSomething($i);
}

// Same as above, but slow
for($i = 0; $i < count($array); ++$i) {
    doSomething($i);
}

// Same as above, but slow
foreach($portions as &$portion) {
    // here, array_sum() doesn't depends on the $grade. It should be out of the loop
    $portion = $portion / array_sum($portions);
}

$total = array_sum($portion);
foreach($portion as &$portion) {
    $portion = $portion / $total;
}

?>

This is true with any kind of functioncall that returns the same value throughout the loop.

Short name Structures/ForWithFunctioncall
Rulesets Performances, Top10
Severity Minor
Time To Fix Slow (1 hour)
ClearPHP no-functioncall-in-loop

9.215. Foreach Don’t Change Pointer

foreach loops use their own internal cursor.

A foreach loop won’t change the internal pointer of the array, as it works on a copy of the source. Hence, applying array pointer’s functions such as current() or next() to the source array won’t have the same behavior in PHP 5 than PHP 7.

This only applies when a foreach() by reference is used.

<?php

$numbers = range(1, 10);
next($numbers);
foreach($numbers as &$number){
    print $number;
    print current($numbers).\n; // Always
}

?>

See also foreach no longer changes the internal array pointer and foreach.

Short name Php/ForeachDontChangePointer
Rulesets CompatibilityPHP70
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Slow (1 hour)

9.216. Foreach On Object

Foreach on object looks like a typo. This is particularly true when both object and member are variables.

Foreach on an object member is a legit PHP syntax, though it is very rare : blind variables rarely have to be securing in an object to be processed.

<?php

// Looks suspicious
foreach($array as $o -> $b) {
    doSomething();
}

// This is the real thing
foreach($array as $o => $b) {
    doSomething();
}

?>
Short name Php/ForeachObject
Rulesets Analyze
Severity Major
Time To Fix Instant (5 mins)

9.217. Foreach Reference Is Not Modified

Foreach statement may loop using a reference, especially when the loop has to change values of the array it is looping on.

In the spotted loop, reference are used but never modified. They may be removed.

<?php

$letters = range('a', 'z');

// $letter is not used here
foreach($letters as &$letter) {
    $alphabet .= $letter;
}

// $letter is actually used here
foreach($letters as &$letter) {
    $letter = strtoupper($letter);
}

?>

9.217.1. Suggestions

  • Remove the reference from the foreach
  • Actually modify the content of the reference
Short name Structures/ForeachReferenceIsNotModified
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples Dolibarr, Vanilla

9.218. Foreach With list()

Foreach loops have the ability to use list as blind variables. This syntax assign directly array elements to various variables.

PHP 5.5 introduced the usage of list in foreach() loops. Until PHP 7.1, it was not possible to use non-numerical arrays as list() wouldn’t support string-indexed arrays.

<?php
    // PHP 5.5 and later, with numerically-indexed arrays
    foreach($array as list($a, $b)) {
        // do something
    }


    // PHP 7.1 and later, with arrays
    foreach($array as list('col1' => $a, 'col3' => $b)) { // 'col2 is ignored'
        // do something
    }
?>

Previously, it was compulsory to extract() the data from the blind array :

<?php
    foreach($array as $c) {
        list($a, $b) = $c;
        // do something
    }
?>

See also The list function & practical uses of array destructuring in PHP.

Short name Structures/ForeachWithList
Rulesets CompatibilityPHP53, CompatibilityPHP54
Php Version With PHP 5.5 and more recent
Severity Minor
Time To Fix Slow (1 hour)

9.219. Forgotten Interface

The following classes have been found implementing an interface’s methods, though it doesn’t explicitly implements this interface. This may have been forgotten.

<?php

interface i {
    function i();
}

// i is not implemented and declared
class foo {
    function i() {}
    function j() {}
}

// i is implemented and declared
class foo implements i {
    function i() {}
    function j() {}
}

?>

See also could-use-trait.

9.219.1. Suggestions

  • Mention interfaces explicitly whenever possible
Short name Interfaces/CouldUseInterface
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.220. Forgotten Thrown

An exception is instantiated, but not thrown.

<?php

class MyException extends \Exception { }

if ($error !== false) {
    // This looks like 'throw' was omitted
    new MyException();
}

?>

9.220.1. Suggestions

  • Remove the throw expression
  • Add the new to the throw expression
Short name Exceptions/ForgottenThrown
Rulesets Analyze
Severity Major
Time To Fix Instant (5 mins)

9.221. Forgotten Visibility

Some classes elements (property, method, constant) are missing their explicit visibility.

By default, it is public. It should at least be mentioned as public, or may be reviewed as protected or private.

Class constants support also visibility since PHP 7.1.

final, static and abstract are not counted as visibility. Only public, private and protected. The PHP 4 var keyword is counted as undefined.

Traits, classes and interfaces are checked.

<?php

// Explicit visibility
class X {
    protected sconst NO_VISIBILITY_CONST = 1; // For PHP 7.2 and later

    private $noVisibilityProperty = 2;

    public function Method() {}
}

// Missing visibility
class X {
    const NO_VISIBILITY_CONST = 1; // For PHP 7.2 and later

    var $noVisibilityProperty = 2; // Only with var

    function NoVisibilityForMethod() {}
}

?>

See also Visibility and Understanding The Concept Of Visibility In Object Oriented PHP.

9.221.1. Suggestions

  • Always add explicit visibility to methods and constants in a class
  • Always add explicit visibility to properties in a class, after PHP 7.4
Short name Classes/NonPpp
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP always-have-visibility
Examples FuelCMS, LiveZilla

9.222. Forgotten Whitespace

Forgotten whitespaces only bring misery to the code.

White spaces have been left at either end of a file : before the PHP opening tag, or after the closing tag.

Usually, such whitespaces are forgotten, and may end up summoning the infamous ‘headers already sent’ error. It is better to remove them.

<?php
    // This script has no forgotten whitespace, not at the beginning
    function foo() {}

    // This script has no forgotten whitespace, not at the end
?>

See also How to fix Headers already sent error in PHP.

9.222.1. Suggestions

  • Remove all whitespaces before and after a script. This doesn’t apply to template, which may need to use those spaces.
  • Remove the final tag, to prevent any whitespace to be forgotten at the end of the file. This doesn’t apply to the opening PHP tag, which is always necessary.
Short name Structures/ForgottenWhiteSpace
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)

9.223. Fossilized Method

A method is fossilized when it is overwritten so often that changing a default value, a return type or an argument type is getting difficult.

This happens when a class is extended. When a method is overwritten once, it may be easy to update the signature in two places. The more methods are overwriting a parent method, the more difficult it is to update it.

This analysis counts the number of times a method is overwritten, and report any method that is ovrewritten more than 6 times. This threshold may be configured.

<?php

class x1 {
    // foo1() is never overwritten. It is easy to update.
    function foo1() {}

    // foo7() is overwritten seven times. It is hard to update.
    function foo7() {}
}

// classes x2 to x7, all overwrite foo7();
// Only x2 is presente here.
class x2 extends x1 {
    function foo7() {}
}

?>
Name Default Type Description
fossilizationThreshold 6 integer Minimal number of overwriting methods to consider a method difficult to update.
Short name Classes/FossilizedMethod
Rulesets ClassReview, Typechecks
Severity Minor
Time To Fix Quick (30 mins)

9.224. Fully Qualified Constants

Constants defined with their namespace.

When defining constants with define() function, it is possible to include the actual namespace :

<?php

define('a\b\c', 1);

?>

However, the name should be fully qualified without the initial . Here, abc constant will never be accessible as a namespace constant, though it will be accessible via the constant() function.

Also, the namespace will be absolute, and not a relative namespace of the current one.

9.224.1. Suggestions

  • Drop the initial when creating constants with define() : for example, use trim($x, ‘’), which removes anti-slashes before and after.
Short name Namespaces/ConstantFullyQualified
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)

9.225. Function Subscripting

It is possible to use the result of a methodcall directly as an array, without storing the result in a temporary variable.

This works, given that the method actually returns an array.

This syntax was not possible until PHP 5.4. Until then, it was compulsory to store the result in a variable first. Although this is now superfluous, it has been a standard syntax in PHP, and is still being used.

<?php

function foo() {
    return array(1 => 'a', 'b', 'c');
}

echo foo()[1]; // displays 'a';

// Function subscripting, the old way
function foo() {
    return array(1 => 'a', 'b', 'c');
}

$x = foo();
echo $x[1]; // displays 'a';

?>

Storing the result in a variable is still useful if the result is actually used more than once.

Short name Structures/FunctionSubscripting
Rulesets CompatibilityPHP53
Php Version With PHP 5.4 and more recent
Severity Minor
Time To Fix Instant (5 mins)

9.226. Function Subscripting, Old Style

Since PHP 5.4, it is now possible use function results as an array, and access directly its element :

<?php

function foo() {
    return array(1 => 'a', 'b', 'c');
}

echo foo()[1]; // displays 'a';

// Function subscripting, the old way
function foo() {
    return array(1 => 'a', 'b', 'c');
}

$x = foo();
echo $x[1]; // displays 'a';

?>

9.226.1. Suggestions

  • Skip the local variable and directly use the return value from the function
Short name Structures/FunctionPreSubscripting
Rulesets Suggestions
Php Version With PHP 5.4 and more recent
Severity Minor
Time To Fix Instant (5 mins)
Examples OpenConf

9.227. Functions Removed In PHP 5.4

Those functions were removed in PHP 5.4.

<?php

// Deprecated as of PHP 5.4.0
$link = mysql_connect('localhost', 'mysql_user', 'mysql_password');
$db_list = mysql_list_dbs($link);

while ($row = mysql_fetch_object($db_list)) {
     echo $row->Database . "\n";
}

?>

See also Deprecated features in PHP 5.4.x.

Short name Php/Php54RemovedFunctions
Rulesets CompatibilityPHP54
Php Version With PHP 5.4 and older
Severity Major
Time To Fix Quick (30 mins)

9.228. Functions Removed In PHP 5.5

Those functions were removed in PHP 5.5.

<?php

echo '<img src="' . $_SERVER['PHP_SELF'] .
     '?=' . php_logo_guid() . '" alt="PHP Logo !" />';

?>

See also Deprecated features in PHP 5.5.x.

9.228.1. Suggestions

  • Stop using those functions
Short name Php/Php55RemovedFunctions
Rulesets CompatibilityPHP55
Php Version With PHP 5.5 and older
Severity Major
Time To Fix Quick (30 mins)

9.229. Generator Cannot Return

Generators could not use return and yield at the same time. In PHP 7.0, generator can now use both of them.

<?php

// This is not allowed until PHP 7.0
function foo() {
    yield 1;
    return 'b';
}

?>

9.229.1. Suggestions

  • Remove the return
Short name Functions/GeneratorCannotReturn
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version 7.0+
Severity Major
Time To Fix Quick (30 mins)

9.230. Getting Last Element

Getting the last element of an array relies on array_key_last().

array_key_last() was added in PHP 7.3. Before that,

<?php

$array = ['a' => 1, 'b' => 2, 'c' => 3];

// Best solutions, by far
$last = $array[array_key_last($array)];

// Best solutions, just as fast as each other
$last = $array[count($array) - 1];
$last = end($array);

// Bad solutions

// popping, but restoring the value.
$last = array_pop($array);
$array[] = $last;

// array_unshift would be even worse

// reversing array
$last = array_reverse($array)[0];

// slicing the array
$last = array_slice($array, -1)[0]',
$last = current(array_slice($array, -1));
);

?>

9.230.1. Suggestions

  • Use PHP native function : array_key_last(), when using PHP 7.4 and later
  • Use PHP native function : array_pop()
  • Organise the code to put the last element in the first position (array_unshift() instead of append operator [])
Short name Arrays/GettingLastElement
Rulesets Performances
Severity Minor
Time To Fix Instant (5 mins)
Examples Thelia

9.231. Global Inside Loop

The global keyword must be used out of loops. Otherwise, it is evaluated each loop, slowing the whole process.

<?php

// Here, global is used once
global $total;
foreach($a as $b) {
    $total += $b;
}

// Global is called each time : this is slow.
foreach($a as $b) {
    global $total;
    $total += $b;
}
?>

9.231.1. Suggestions

  • Move the global keyword outside the loop
Short name Structures/GlobalOutsideLoop
Rulesets Performances

9.232. Global Usage

List usage of globals variables, with global keywords or direct access to $GLOBALS.

<?php
$a = 1; /* global scope */

function test()
{
    echo $a; /* reference to local scope variable */
}

test();

?>

It is recommended to avoid using global variables, at it makes it very difficult to track changes in values across the whole application.

See also Variable scope.

Short name Structures/GlobalUsage
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
ClearPHP no-global

9.233. Group Use Declaration

The group use declaration is used in the code.

<?php

// Adapted from the RFC documentation
// Pre PHP 7 code
use some\name_space\ClassA;
use some\name_space\ClassB;
use some\name_space\ClassC as C;

use function some\name_space\fn_a;
use function some\name_space\fn_b;
use function some\name_space\fn_c;

use const some\name_space\ConstA;
use const some\name_space\ConstB;
use const some\name_space\ConstC;

// PHP 7+ code
use some\name_space\{ClassA, ClassB, ClassC as C};
use function some\name_space\{fn_a, fn_b, fn_c};
use const some\name_space\{ConstA, ConstB, ConstC};

?>

See also Group Use Declaration RFC and Using namespaces: Aliasing/Importing.

Short name Php/GroupUseDeclaration
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Severity Minor
Time To Fix Instant (5 mins)

9.234. Group Use Trailing Comma

The usage of a final empty slot in array() was allowed with use statements. This works in PHP 7.2 and more recent.

Although this empty instruction is ignored at execution, this allows for clean presentation of code, and short diff when committing in a VCS.

<?php

// Valid in PHP 7.2 and more recent.
use a\b\{c,
         d,
         e,
         f,
        };

// This won't compile in 7.1 and older.

?>

See also Trailing Commas In List Syntax and Revisit trailing commas in function arguments.

Short name Php/GroupUseTrailingComma
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.2 and more recent
Severity Major
Time To Fix Instant (5 mins)

9.235. Hardcoded Passwords

Hardcoded passwords in the code.

Hardcoding passwords is a bad idea. Not only it make the code difficult to change, but it is an information leak. It is better to hide this kind of information out of the code.

<?php

$ftp_server = '300.1.2.3';   // yes, this doesn't exists, it's an example
$conn_id = ftp_connect($ftp_server);

// login with username and password
$login_result = ftp_login($conn_id, 'login', 'password');

?>

See also 10 GitHub Security Best Practices and Git How-To: Remove Your Password from a Repository.

9.235.1. Suggestions

  • Remove all passwords from the code. Also, check for history if you are using a VCS.
Name Default Type Description
passwordsKeys password_keys.json data List of array index and property names that shall be checked for potential secret key storages.
Short name Functions/HardcodedPasswords
Rulesets Analyze, Security
Severity Major
Time To Fix Slow (1 hour)
ClearPHP no-hardcoded-credential

9.236. Hash Algorithms

There is a long but limited list of hashing algorithm available to PHP. The one found doesn’t seem to be existing.

<?php

// This hash has existed in PHP. Check with hash_algos() if it is available on your system.
echo hash('ripmed160', 'The quick brown fox jumped over the lazy dog.');

// This hash doesn't exist
echo hash('ripemd160', 'The quick brown fox jumped over the lazy dog.');

?>

See also hash_algos.

9.236.1. Suggestions

  • Use a hash algorithm that is available on several PHP versions
  • Fix the name of the hash algorithm
Short name Php/HashAlgos
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)

9.237. Hash Algorithms Incompatible With PHP 5.3

List of hash algorithms incompatible with PHP 5.3.

<?php

// Compatible only with 5.3 and more recent
echo hash('md2', 'The quick brown fox jumped over the lazy dog.');

// Always compatible
echo hash('ripemd320', 'The quick brown fox jumped over the lazy dog.');

?>

See also hash_algos.

Short name Php/HashAlgos53
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56, CompatibilityPHP72
Severity Major
Time To Fix Slow (1 hour)

9.238. Hash Algorithms Incompatible With PHP 5.4/5.5

List of hash algorithms incompatible with PHP 5.4 and 5.5.

<?php

// Compatible only with 5.4 and more recent
echo hash('fnv132', 'The quick brown fox jumped over the lazy dog.');

// Always compatible
echo hash('ripemd320', 'The quick brown fox jumped over the lazy dog.');

?>

See also hash_algos.

Short name Php/HashAlgos54
Rulesets CompatibilityPHP54, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP55, CompatibilityPHP56, CompatibilityPHP72
Php Version With PHP 5.4 and older
Severity Major
Time To Fix Slow (1 hour)

9.239. Hash Algorithms Incompatible With PHP 7.1-

List of hash algorithms incompatible with PHP 7.1 and more recent. At the moment of writing, this is compatible up to 7.3.

The hash algorithms were introduced in PHP 7.1.

<?php

// Compatible only with 7.1 and more recent
echo hash('sha512/224', 'The quick brown fox jumped over the lazy dog.');

// Always compatible
echo hash('ripemd320', 'The quick brown fox jumped over the lazy dog.');

?>

See also hash_algos.

Short name Php/HashAlgos71
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.1 and older
Severity Major
Time To Fix Slow (1 hour)

9.240. Hash Algorithms Incompatible With PHP 7.4-

List of hash algorithms incompatible with PHP 7.3 and older recent. At the moment of writing, this is compatible up to 7.4s.

The hash algorithms were introduced in PHP 7.4s.

<?php

// Compatible only with 7.1 and more recent
echo hash('crc32cs', 'The quick brown fox jumped over the lazy dog.');

// Always compatible
echo hash('ripemd320', 'The quick brown fox jumped over the lazy dog.');

?>

See also hash_algos.

Short name Php/HashAlgos74
Rulesets CompatibilityPHP74
Php Version With PHP 7.4 and older
Severity Major
Time To Fix Slow (1 hour)

9.241. Hash Will Use Objects

The ext/hash extension used resources, and is being upgraded to use resources.

<?php

// Post 7.2 code
    $hash = hash_init('sha256');
    if (!is_object($hash)) {
        trigger_error('error');
    }
    hash_update($hash, $message);

// Pre-7.2 code
    $hash = hash_init('md5');
    if (!is_resource($hash)) {
        trigger_error('error');
    }
    hash_update($hash, $message);

?>

See also Move ext/hash from resources to objects.

Short name Php/HashUsesObjects
Rulesets CompatibilityPHP72
Severity Major
Time To Fix Quick (30 mins)

9.242. Heredoc Delimiter

Heredoc and Nowdoc expressions may use a variety of delimiters.

There seems to be a standard delimiter in the code, and some exceptions : one or several forms are dominant (> 90%), while the others are rare.

The analyzed code has less than 10% of the rare delimiters. For consistency reasons, it is recommended to make them all the same.

Generally, one or two delimiters are used, with generic value. It is recommended to use a humanly readable delimiter : SQL, HTML, XML, GREMLIN, etc. This helps readability in the code.

<?php

echo <<<SQL
SELECT * FROM table1;
SQL;

echo <<<SQL
SELECT * FROM table2;
SQL;

echo <<<SQL
SELECT * FROM table3;
SQL;

echo <<<SQL
SELECT * FROM table4;
SQL;

echo <<<SQL
SELECT * FROM table5;
SQL;

echo <<<SQL
SELECT * FROM table11;
SQL;

echo <<<SQL
SELECT * FROM table12;
SQL;

echo <<<SQL
SELECT * FROM table13;
SQL;

// Nowdoc
echo <<<'SQL'
SELECT * FROM table14;
SQL;

echo <<<SQL
SELECT * FROM table15;
SQL;


echo <<<HEREDOC
SELECT * FROM table215;
HEREDOC;

?>
Short name Structures/HeredocDelimiterFavorite
Rulesets Coding Conventions

9.243. Hexadecimal In String

Mark strings that may be confused with hexadecimal.

Until PHP 7.0, PHP recognizes hexadecimal numbers inside strings, and converts them accordingly.

PHP 7.0 and until 7.1, converts the string to 0, silently.

PHP 7.1 and later, emits a ‘A non-numeric value encountered’ warning, and convert the string to 0.

<?php
    $a = '0x0030';
    print $a + 1;
    // Print 49

    $c = '0x0030zyc';
    print $c + 1;
    // Print 49

    $b = 'b0x0030';
    print $b + 1;
    // Print 0
?>
Short name Type/HexadecimalString
Rulesets CompatibilityPHP70, CompatibilityPHP71
Severity Major
Time To Fix Slow (1 hour)

9.244. Hidden Nullable

Argument with default value of null are nullable. Even when the null typehint (PHP 8.0), or the ? operator are not used, setting the default value to null is allowed, and makes the argument nullable.

This doesn’t happen with properties : they must be defined with the nullable type to accept a ``null``value as default value.

This doesn’t happen with constant, which can’t be typehinted.

<?php

// explicit nullable parameter $s
function bar(?string $s = null) {

// implicit nullable parameter $s
function foo(string $s = null) {
    echo $s ?? 'NULL-value';
}

// both display NULL-value
foo();
foo(null);

?>

See also Nullable types and Type declaration.

9.244.1. Suggestions

  • Change the default value to a compatible literal : for example, string $s = ''
  • Add the explicit ? nullable operator, or ``null``with PHP 8.0
  • Remove the default value
Short name Classes/HiddenNullable
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.245. Hidden Use Expression

The use expression for namespaces should always be at the beginning of the namespace block.

It is where everyone expect them, and it is less confusing than having them at various levels.

<?php

// This is visible
use A;

class B {}

// This is hidden
use C as D;

class E extends D {
    use traitT; // This is a use for a trait

    function foo() {
        // This is a use for a closure
        return function ($a) use ($b) {}
    }
}

?>

9.245.1. Suggestions

  • Group all uses together, at the beginning of the namespace or class
Short name Namespaces/HiddenUse
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples Tikiwiki, OpenEMR

9.246. Htmlentities Calls

htmlentities() and htmlspecialchars() are used to prevent injecting special characters in HTML code. As a bare minimum, they take a string and encode it for HTML.

The second argument of the functions is the type of protection. The protection may apply to quotes or not, to HTML 4 or 5, etc. It is highly recommended to set it explicitly.

The third argument of the functions is the encoding of the string. In PHP 5.3, it is ISO-8859-1, in 5.4, was UTF-8, and in 5.6, it is now default_charset, a php.ini configuration that has the default value of UTF-8. It is highly recommended to set this argument too, to avoid distortions from the configuration.

<?php
$str = 'A quote is <b>bold</b>';

// Outputs, without depending on the php.ini: A &#039;quote&#039; is &lt;b&gt;bold&lt;/b&gt;
echo htmlentities($str, ENT_QUOTES, 'UTF-8');

// Outputs, while depending on the php.ini: A quote is &lt;b&gt;bold&lt;/b&gt;
echo htmlentities($str);

?>

Also, note that arguments 2 and 3 are constants and string, respectively, and should be issued from the list of values available in the manual. Other values than those will make PHP use the default values.

See also htmlentities and htmlspecialchars.

9.246.1. Suggestions

  • Always use the third argument with htmlentities()
Short name Structures/Htmlentitiescall
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Instant (5 mins)

9.247. Identical Conditions

These logical expressions contain members that are identical.

This means those expressions may be simplified.

<?php

// twice $a
if ($a || $b || $c || $a) {  }

// Hiding in parenthesis is bad
if (($a) ^ ($a)) {}

// expressions may be large
if ($a === 1 && 1 === $a) {}

?>

9.247.1. Suggestions

  • Merge the two structures into one unique test
  • Add extra expressions between the two structures
  • Nest the structures, to show that different attempts are made
Short name Structures/IdenticalConditions
Rulesets Analyze, CI-checks
Severity Critical
Time To Fix Quick (30 mins)
Examples WordPress, Dolibarr, Mautic

9.248. Identical Consecutive Expression

Identical consecutive expressions are worth being checked.

They may be a copy/paste with unmodified content. When the content has to be duplicated, it is recommended to avoid executing the expression again, and just access the cached result.

<?php

$current  = $array[$i];
$next     = $array[$i + 1];
$nextnext = $array[$i + 1]; // OOps, nextnext is wrong.

// Initialization
$previous = foo($array[1]); // previous is initialized with the first value on purpose
$next     = foo($array[1]); // the second call to foo() with the same arguments should be avoided
// the above can be rewritten as :
$next     = $previous; // save the processing.

for($i = 1; $i < 200; ++$i) {
    $next = doSomething();
}
?>
Short name Structures/IdenticalConsecutive
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)

9.249. Identical On Both Sides

Operands should be different when comparing or making a logical combination. Of course, the value each operand holds may be identical. When the same operand appears on both sides of the expression, the result is know before execution.

<?php

// Trying to confirm consistency
if ($login == $login) {
    doSomething();
}

// Works with every operators
if ($object->login( ) !== $object->login()) {
    doSomething();
}

if ($sum >= $sum) {
    doSomething();
}

//
if ($mask && $mask) {
    doSomething();
}

if ($mask || $mask) {
    doSomething();
}

?>

9.249.1. Suggestions

  • Remove one of the alternative, and remove the logical link
  • Modify one of the alternative, and make it different from the other
Short name Structures/IdenticalOnBothSides
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples phpMyAdmin, HuMo-Gen

9.250. If With Same Conditions

Successive If / then structures that have the same condition may be either merged or have one of the condition changed.

<?php

if ($a == 1) {
    doSomething();
}

if ($a == 1) {
    doSomethingElse();
}

// May be replaced by
if ($a == 1) {
    doSomething();
    doSomethingElse();
}

?>

Note that if the values used in the condition have been modified in the first if/then structure, the two distinct conditions may be needed.

<?php

// May not be merged
if ($a == 1) {
    // Check that this is really the situation
    $a = checkSomething();
}

if ($a == 1) {
    doSomethingElse();
}

?>

9.250.1. Suggestions

  • Merge the two conditions so the condition is used once.
  • Change one of the condition, so they are different
  • Make it obvious that the first condition is a try, preparing the normal conditions.
Short name Structures/IfWithSameConditions
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples phpMyAdmin, Phpdocumentor

9.251. Iffectations

Affectations that appears in a condition.

Iffectations are a way to do both a test and an affectations. They may also be typos, such as if ($x = 3) { }, leading to a constant condition.

<?php

// an iffectation : assignation in a If condition
if($connexion = mysql_connect($host, $user, $pass)) {
    $res = mysql_query($connexion, $query);
}

// Iffectation may happen in while too.
while($row = mysql_fetch($res)) {
    $store[] = $row;
}

?>

9.251.1. Suggestions

  • Move the assignation inside the loop, and make an existence test in the condition.
  • Move the assignation before the if/then, make an existence test in the condition.
Short name Structures/Iffectation
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Precision Very high

9.252. Illegal Name For Method

PHP has reserved usage of methods starting with __ for magic methods. It is recommended to avoid using this prefix, to prevent confusions.

<?php

class foo{
    // Constructor
    function __construct() {}

    // Constructor's typo
    function __constructor() {}

    // Illegal function name, even as private
    private function __bar() {}
}

?>

See also Magic Methods.

9.252.1. Suggestions

  • Avoid method names starting with a double underscore : __
  • Use method visibilities to ensure that methods are only available to the current class or its children
Short name Classes/WrongName
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)
Examples PrestaShop, Magento

9.253. Implement Is For Interface

With class heritage, implements should be used for interfaces, and extends with classes.

PHP defers the implements check until execution : the code in example does lint, but won,t run.

<?php

class x {
    function foo() {}
}

interface y {
    function foo();
}

// Use implements with an interface
class z implements y {}

// Implements is for an interface, not a class
class z implements x {}

?>

9.253.1. Suggestions

  • Create an interface from the class, and use it with the implements keyword
Short name Classes/ImplementIsForInterface
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.254. Implemented Methods Are Public

Class methods that are defined in an interface must be public. They cannot be either private, nor protected.

This error is not reported by lint, but is reported at execution time.

<?php

interface i {
    function foo();
}

class X {
    // This method is defined in the interface : it must be public
    protected function foo() {}

    // other methods may be private
    private function bar() {}
}

?>

See also Interfaces and Interfaces - the next level of abstraction.

9.254.1. Suggestions

  • Make the implemented method public
Short name Classes/ImplementedMethodsArePublic
Rulesets Analyze
Severity Major
Time To Fix Instant (5 mins)

9.255. Implied If

It is confusing to emulate if/then with boolean operators.

It is possible to emulate a if/then structure by using the operators ‘and’ and ‘or’. Since optimizations will be applied to them : when the left operand of ‘and’ is false, the right one is not executed, as its result is useless; when the left operand of ‘or’ is true, the right one is not executed, as its result is useless;

However, such structures are confusing. It is easy to misread them as conditions, and ignore an important logic step.

<?php

// Either connect, or die
mysql_connect('localhost', $user, $pass) or die();

// Defines a constant if not found.
defined('SOME_CONSTANT') and define('SOME_CONSTANT', 1);

// Defines a default value if provided is empty-ish
// Warning : this is
$user = $_GET['user'] || 'anonymous';

?>

It is recommended to use a real ‘if then’ structures, to make the condition readable.

Short name Structures/ImpliedIf
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Instant (5 mins)
ClearPHP no-implied-if

9.256. Implode One Arg

implode() may be called with one arg. It is recommended to avoid it.

Using two arguments makes it less surprising to new comers, and consistent with explode() syntax.

<?php

$array = range('a', 'c');

// empty string is the glue
print implode('', $array);

// only the array : PHP uses the empty string as glue.
// Avoid this
print implode($array);

?>

See also implode.

9.256.1. Suggestions

  • Add an empty string as first argument
Short name Php/ImplodeOneArg
Rulesets Suggestions, php-cs-fixable
Severity Minor
Time To Fix Quick (30 mins)

9.257. Implode() Arguments Order

implode() accepted two signatures, but is only recommending one. Both types orders of string then array, and array then string have been possible until PHP 7.4.

In PHP 7.4, the order array then string is deprecated, and emits a warning. It will be removed in PHP 8.0.

<?php

$glue = ',';
$pieces = range(0, 4);

// documented argument order
$s = implode($glue, $pieces);

// Pre 7.4 argument order
$s = implode($pieces, $glue);

// both produces 0,1,2,3,4

?>

See also implode().

9.257.1. Suggestions

  • Always use the array as the second argument
Short name Structures/ImplodeArgsOrder
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.258. Inclusion Wrong Case

Inclusion should follow exactly the case of included files and path. This prevents the infamous case-sensitive filesystem bug, where files are correctly included in a case-insensitive system, and failed to be when moved to production.

<?php

// There must exist a path called path/to and a file library.php with this case
include path/to/library.php;

// Error on the case, while the file does exist
include path/to/LIBRARY.php;

// Error on the case, on the PATH
include path/TO/library.php;

?>

See also include_once, about case sensitivity and inclusions.

9.258.1. Suggestions

  • Make the inclusion string identical to the file name.
  • Change the name of the file to reflect the actual inclusion. This is the best way when a naming convention has been set up for the project, and the file doesn’t adhere to it. Remember to change all other inclusion.
Short name Files/InclusionWrongCase
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)

9.259. Incompatible Signature Methods

Methods should have the same signature when being overwritten.

The same signatures means the children class must have : + the same name + the same visibility or less restrictive + the same typehint or removed + the same default value or removed + a reference like its parent

This problem emits a fatal error, for abstract methods, or a warning error, for normal methods. Yet, it is difficult to lint, because classes are often stored in different files. As such, PHP do lint each file independently, as unknown parent classes are not checked if not present. Yet, when executing the code, PHP lint the actual code and may encounter a fatal error.

<?php

class a {
    public function foo($a = 1) {}
}

class ab extends a {
    // foo is overloaded and now includes a default value for $a
    public function foo($a) {}
}

?>

See also Object Inheritance.

9.259.1. Suggestions

  • Make signatures compatible again
Short name Classes/IncompatibleSignature
Rulesets Analyze, LintButWontExec
Php Version 7.4-
Severity Critical
Time To Fix Quick (30 mins)
Examples SuiteCrm

9.260. Incompatible Signature Methods With Covariance

Methods should have the compatible signature when being overwritten.

The same signatures means the children class must have : + the same name + the same visibility or less restrictive + the same contravariant typehint or removed + the same covariant return typehint or removed + the same default value or removed + a reference like its parent

This problem emits a fatal error, for abstract methods, or a warning error, for normal methods. Yet, it is difficult to lint, because classes are often stored in different files. As such, PHP do lint each file independently, as unknown parent classes are not checked if not present. Yet, when executing the code, PHP lint the actual code and may encounter a fatal error.

<?php

class a {
    public function foo($a = 1) {}
}

class ab extends a {
    // foo is overloaded and now includes a default value for $a
    public function foo($a) {}
}

?>
See also Object Inheritance,
PHP RFC: Covariant Returns and Contravariant Parameters and Incompatible Signature Methods.

9.260.1. Suggestions

  • Make signatures compatible again
Short name Classes/IncompatibleSignature74
Rulesets Analyze
Php Version 7.4+
Severity Critical
Time To Fix Quick (30 mins)
Examples SuiteCrm

9.261. Incompilable Files

Files that cannot be compiled, and, as such, be run by PHP. Scripts are linted against various versions of PHP.

This is usually undesirable, as all code must compile before being executed. It may be that such files are not compilable because they are not yet ready for an upcoming PHP version.

<?php

// Can't compile this : Print only accepts one argument
print $a, $b, $c;

?>

Code that is not compilable with older PHP versions means that the code is breaking backward compatibility : good or bad is project decision.

When the code is used as a template for PHP code generation, for example at installation time, it is recommended to use a distinct file extension, so as to distinguish them from actual PHP code.

9.261.1. Suggestions

  • If this file is a template for PHP code, change the extension to something else than .php
  • Fix the syntax so it works with various versions of PHP
Short name Php/Incompilable
Rulesets Analyze
Severity Critical
Time To Fix Slow (1 hour)
ClearPHP no-incompilable
Examples xataface

9.262. Inconsistent Elseif

Chaining if/elseif requires a consistent string of conditions. The conditions are executed one after the other, and the conditions shouldn’t overlap.

This analysis reports chains of elseif that don’t share a common variable (or array, or property, etc.. ). As such, testing different conditions are consistent.

<?php

// $a is always common, so situations are mutually exclusive
if ($a === 1) {
    doSomething();
} else if ($a > 1) {
    doSomethingElse();
} else {
    doSomethingDefault();
}

// $a is always common, so situations are mutually exclusive
// although, it may be worth checking the consistency here
if ($a->b === 1) {
    doSomething();
} else if ($a->c > 1) {
    doSomethingElse();
} else {
    doSomethingDefault();
}

// if $a === 1, then $c doesn't matter?
// This happens, but then logic doesn't appear in the code.
if ($a === 1) {
    doSomething();
} else if ($c > 1) {
    doSomethingElse();
} else {
    doSomethingDefault();
}

?>
Short name Structures/InconsistentElseif
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)

9.263. Indices Are Int Or String

Indices in an array notation such as $array['indice'] may only be integers or string.

Boolean, Null or float will be converted to their integer or string equivalent.

<?php
    $a = [true => 1,
          1.0  => 2,
          1.2  => 3,
          1    => 4,
          '1'  => 5,
          0.8  => 6,
          0x1  => 7,
          01   => 8,

          null  => 1,
          ''    => 2,

          false => 1,
          0     => 2,

          '0.8' => 3,
          '01'  => 4,
          '2a'  => 5
          ];

    print_r($a);

/*
The above displays
Array
(
    [1] => 8
    [0] => 2
    [] => 2
    [0.8] => 3
    [01] => 4
    [2a] => 5
)
*/
?>

Decimal numbers are rounded to the closest integer; Null is transtyped to ‘’ (empty string); true is 1 and false is 0; Integers in strings are transtyped, while partial numbers or decimals are not analyzed in strings.

As a general rule of thumb, only use integers or strings that don’t look like integers.

This analyzer may find constant definitions, when available.

Note also that PHP detects integer inside strings, and silently turn them into integers. Partial and octal numbers are not transformed.

<?php
    $a = [1      => 1,
          '2'    => 2,
          '011'  => 9, // octal number
          '11d'  => 11, // partial number
          ];

    var_dump($a);

/*
The above displays
array(4) {
  [1]=>
  int(1)
  [2]=>
  int(2)
  [011]=>
  int(9)
  [11d]=>
  int(11)
}*/
?>

See also Arrays syntax.

9.263.1. Suggestions

  • Do not use any type but string or integer
  • Force typecast the keys when building an array
Short name Structures/IndicesAreIntOrString
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples Zencart, Mautic

9.264. Indirect Injection

Look for injections through indirect usage for GPRC values ($_GET, $_POST, $_REQUEST, $_COOKIE).

<?php

$a = $_GET['a'];
echo $a;

function foo($b) {
    echo $b;
}
foo($_POST['c']);

?>

9.264.1. Suggestions

  • Always validate incoming values before using them.
Short name Security/IndirectInjection
Rulesets Security
Severity Critical
Time To Fix Slow (1 hour)

9.265. Infinite Recursion

A method is calling itself, with unchanged arguments. This will probably repeat indefinitely.

This applies to recursive functions without any condition. This also applies to function which inject the incoming arguments, without modifications.

<?php

function foo($a, $b) {
    if ($a > 10) {
        return;
    }
    foo($a, $b);
}

function foo2($a, $b) {
    ++$a;   // $a is modified
    if ($a > 10) {
        return;
    }
    foo2($a, $b);
}

?>

9.265.1. Suggestions

  • Modify arguments before injecting them again in the same method
  • Use different values when calling the same method
Short name Structures/InfiniteRecursion
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.266. Instantiating Abstract Class

PHP cannot instantiate an abstract class.

The classes are actually abstract classes, and should be derived into a concrete class to be instantiated.

<?php

abstract class Foo {
    protected $a;
}

class Bar extends Foo {
    protected $b;
}

// instantiating a concrete class.
new Bar();

// instantiating an abstract class.
// In real life, this is not possible also because the definition and the instantiation are in the same file
new Foo();

?>

See also Class Abstraction.

Short name Classes/InstantiatingAbstractClass
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.267. Insufficient Property Typehint

The typehint used for a class property doesn’t cover all it usage.

The typehint is insufficient when a undefined method is called, or if members are access while the typehint is an interface.

<?php

class A {
    function a1() {}
}

// PHP 7.4 and more recent
class B {
    private A $a = null;

    function b2() {
        // this method is available in A
        $this->a->a1();
        // this method is NOT available in A
        $this->a->a2();
    }
}

// Supported by all PHP versions
class C {
    private $a = null;

    function __construct(A $a) {
        $this->a = $a;
    }

    function b2() {
        // this method is available in A
        $this->a->a1();
        // this method is NOT available in A
        $this->a->a2();
    }
}

?>

This analysis relies on typehinted properties, as introduced in PHP 7.4. It also relies on typehinted assignations at construct time : the typehint of the assigned argument will be used as the property typehint. Getters and setters are not considered here.

9.267.1. Suggestions

  • Change the typehint to match the actual usage of the object in the class.
Short name Classes/InsufficientPropertyTypehint
Rulesets ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.268. Insufficient Typehint

An argument is typehinted, but it actually calls methods that are not listed in the interface.

Classes may be implementing more methods than the one that are listed in the interface they also implements. This means that filtering objects with a typehint, but calling other methods will be solved at execution time : if the method is available, it will be used; if it is not, a fatal error is reported.

<?php

class x implements i {
    function methodI() {}
    function notInI() {}
}

interface i {
    function methodI();
}

function foo(i $x) {
    $x->methodI(); // this call is valid
    $x->notInI();  // this call is not garanteed
}
?>

Inspired by discussion with Brandon Savage.

9.268.1. Suggestions

  • Extend the interface with the missing called methods
  • Change the body of the function to use only the methods that are available in the interface
  • Change the used objects so they don’t depend on extra methods
Short name Functions/InsufficientTypehint
Rulesets Analyze, Typechecks
Severity Major
Time To Fix Quick (30 mins)

9.269. Integer As Property

It is backward incompatible to use integers are property names. This feature was introduced in PHP 7.2.

If the code must be compatible with previous versions, avoid casting arrays to object.

<?php

// array to object
$arr = [0 => 1];
$obj = (object) $arr;
var_dump(
    $obj,
    $obj->{'0'}, // PHP 7.2+ accessible
    $obj->{0} // PHP 7.2+ accessible

    $obj->{'b'}, // always been accessible
);
?>

See also PHP RFC: Convert numeric keys in object/array casts.

Short name Classes/IntegerAsProperty
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.2 and more recent
Severity Major
Time To Fix Slow (1 hour)

9.270. Integer Conversion

Comparing incoming variables to integer may lead to injection.

When comparing a variable to an integer, PHP applies type juggling, and transform the variable in an integer too. When the value converts smoothly to an integer, this means the validation may pass and yet, the value may carry an injection.

<?php

// This is safer
if ($_GET['x'] === 2) {
    echo $_GET['x'];
}

// Using (int) for validation and display
if ((int) $_GET['x'] === 2) {
    echo (int) $_GET['x'];
}

// This is an injection
if ($_GET['x'] == 2) {
    echo $_GET['x'];
}

// This is unsafe, as $_GET['x']  is tester as an integer, but echo'ed raw
if ((int) $_GET['x'] === 2) {
    echo $_GET['x'];
}

?>

This analysis spots situations where an incoming value is compared to an integer. The usage of the validated value is not considered.

See also Type Juggling Authentication Bypass Vulnerability in CMS Made Simple, PHP STRING COMPARISON VULNERABILITIES and PHP Magic Tricks: Type Juggling.

9.270.1. Suggestions

Short name Security/IntegerConversion
Rulesets Security
Severity Major
Time To Fix Quick (30 mins)

9.271. Interfaces Don’t Ensure Properties

When using an interface as a typehint, properties are not enforced, nor available.

An interface is a template for a class, which specify the minimum amount of methods and constants. Properties are never defined in an interface, and should not be relied upon.

<?php

interface i {
    function m () ;
}

class x implements i {
    public $p = 1;

    function m() {
        return $this->p;
    }
}

function foo(i $i, x $x) {
    // this is invalid, as $p is not defined in i, so it may be not available
    echo $i->p;

    // this is valid, as $p is defined in $x
    echo $x->p;
}

?>

9.271.1. Suggestions

  • Use classes for typehint when properties are accessed
  • Only use methods and constants which are available in the interface
Short name Interfaces/NoGaranteeForPropertyConstant
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.272. Interfaces Is Not Implemented

Classes that implements interfaces, must implements each of the interface’s methods.

<?php

class x implements i {
    // This method implements the foo method from the i interface
    function foo() {}

    // The method bar is missing, yet is requested by interface i
    function foo() {}
}

interface i {
    function foo();
    function bar();
}

?>

This problem tends to occur in code that splits interfaces and classes by file. This means that PHP’s linting will skip the definitions and not find the problem. At execution time, the definitions will be checked, and a Fatal error will occur.

This situation usually detects code that was forgotten during a refactorisation of the interface or the class and its sibblings.

See also Interfaces.

9.272.1. Suggestions

  • Implements all the methods from the interfaces
  • Remove the class
  • Make the class abstract
  • Make the missing methods abstract
Short name Interfaces/IsNotImplemented
Rulesets Analyze, ClassReview, LintButWontExec, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.273. Interpolation

The following strings contain variables that are will be replaced. However, the following characters are ambiguous, and may lead to confusion.

<?php

class b {
    public $b = 'c';
    function __toString() { return __CLASS__; }
}
$x = array(1 => new B());

// -> after the $x[1] looks like a 2nd dereferencing, but it is not.
print $x[1]->b;
// displays : b->b

print {$x[1]->b};
// displays : c

?>

It is advised to add curly brackets around those structures to make them non-ambiguous.

See also Double quoted.

Short name Type/StringInterpolation
Rulesets Coding Conventions
Severity Minor
Time To Fix Quick (30 mins)

9.274. Invalid Constant Name

There is a naming convention for PHP constants names.

According to PHP’s manual, constant names, ‘ A valid constant name starts with a letter or underscore, followed by any number of letters, numbers, or underscores.’.

Constant, must follow this regex : /[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*/.

In particular when defined using define() function, no error is produced. When using const, on the other hand, the

<?php

define('+3', 1); // wrong constant!

echo constant('+3'); // invalid constant access

?>

See also Constants.

9.274.1. Suggestions

  • Change constant name
Short name Constants/InvalidName
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)
Examples OpenEMR

9.275. Invalid Octal In String

Any octal sequence inside a string can’t be go 7. Those will be a fatal error at parsing time.

The check is applied to the string, starting with PHP 7.1. In PHP 7.0 and older, those sequences were silently adapted (modulo/% 0).

<?php

// A valid octal in a PHP string
echo 0; // @

// Emit a warning in PHP 7.1
//Octal escape sequence overflow 0 is greater than 7
echo 0; // @

// Silent conversion
echo 8; // 8

?>

See also Integers.

9.275.1. Suggestions

  • Use a double slash to avoid the sequence to be an octal sequence
  • Use a function call, such as decoct() to convert larger number to octal notation
Short name Type/OctalInString
Rulesets CompatibilityPHP71
Php Version With PHP 7.1 and older
Severity Major
Time To Fix Quick (30 mins)

9.276. Invalid Pack Format

Some characters are invalid in a pack() format string.

pack() and unpack() accept the following format specifiers : aAhHcCsSnviIlLNVqQJPfgGdeExXZ.

unpack() also accepts a name after the format specifier and an optional quantifier.

All other situations is not a valid, and produces a warning : pack(): Type t: unknown format code

<?php
    $binarydata = pack(nvc*, 0x1234, 0x5678, 65, 66);

    // the first unsigned short is stored as 'first'. The next matches are names with numbers.
    $res = unpack('nfirst/vc*', $binarydata);
?>

Check pack() documentation for format specifiers that were introduced in various PHP version, namely 7.0, 7.1 and 7.2.

See also pack and unpack.

9.276.1. Suggestions

  • Fix the packing format with correct values
Short name Structures/InvalidPackFormat
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)

9.277. Invalid Regex

The PCRE regex doesn’t compile. It isn’t a valid regex.

Several reasons may lead to this situation : syntax error, Unknown modifier, missing parenthesis or reference.

<?php

// valid regex
preg_match('/[abc]/', $string);

// invalid regex (missing terminating ] for character class
preg_match('/[abc/', $string);

?>

Regex are check with the Exakat version of PHP.

Dynamic regex are only checked for simple values. Dynamic values may eventually generate a compilation error.

9.277.1. Suggestions

  • Fix the regex before running it
Short name Structures/InvalidRegex
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples SugarCrm

9.278. Is Actually Zero

This addition actually may be simplified because one term is actually negated by another.

This kind of error happens when the expression is very large : the more terms are included, the more chances are that some auto-annihilation happens.

This error may also be a simple typo : for example, calculating the difference between two consecutive terms.

<?php

// This is quite obvious
$a = 2 - 2;

// This is obvious too. This may be a typo-ed difference between two consecutive terms.
// Could have been $c = $fx[3][4] - $fx[3][3] or $c = $fx[3][5] - $fx[3][4];
$c = $fx[3][4] - $fx[3][4];

// This is less obvious
$a = $b[3] - $c + $d->foo(1,2,3) + $c + $b[3];

?>

9.278.1. Suggestions

  • Clean the code and remove the null sum
  • Fix one of the variable : this expression needs another variable here
  • When adding differences, calculate the difference in a temporary variable first.
Short name Structures/IsZero
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples Dolibarr, SuiteCrm

9.279. Is_A() With String

When using is_a() with a string as first argument, the third argument is compulsory.

<?php

// is_a() works with string as first argument, when the third argument is 'true'
if (is_s('A', 'B', true)) {}

// is_a() works with object as first argument
if (is_s(new A, 'A')) {}
?>

See also is_a().

9.279.1. Suggestions

  • Add the third argument, and set it to true
  • Use an object as a first argument
Short name Php/IsAWithString
Rulesets Analyze, Rector, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.280. Isset Multiple Arguments

isset() may be used with multiple arguments and acts as a AND.

<?php

// isset without and
if (isset($a, $b, $c)) {
    // doSomething()
}

// isset with and
if (isset($a) && isset($b) && isset($c)) {
    // doSomething()
}

?>

See also Isset <http://www.php.net/`isset>`_.

9.280.1. Suggestions

  • Merge all isset() calls into one
Short name Php/IssetMultipleArgs
Rulesets Suggestions, php-cs-fixable
Severity Minor
Time To Fix Instant (5 mins)
Examples ThinkPHP, LiveZilla

9.281. Isset() On The Whole Array

Isset() works quietly on a whole array. There is no need to test all previous index before testing for the target index.

<?php

// Straight to the point
if (isset($a[1]['source'])) {
    // Do something with $a[1]['source']
}

// Doing too much work
if (isset($a) && isset($a[1]) && isset($a[1]['source'])) {
    // Do something with $a[1]['source']
}

?>

There is a gain in readability, by avoiding long and hard to read logical expression, and reducing them in one simple isset call.

There is a gain in performances by using one call to isset, instead of several, but it is a micro-optimization.

See also Isset <http://www.php.net/`isset>`_.

9.281.1. Suggestions

  • Remove all unnecessary calls to isset()
Short name Performances/IssetWholeArray
Rulesets Suggestions, Performances
Severity Minor
Time To Fix Instant (5 mins)
Examples Tine20, ExpressionEngine

9.282. Joining file()

Use file() to read lines separately.

Applying join(‘’, ) or implode(‘’, ) to the result of file() provides the same results than using file_get_contents(), but at a higher cost of memory and processing.

If the delimiter is not ‘’, then implode() and file() are a better solution than file_get_contents() and str_replace() or nl2br().

<?php

// memory intensive
$content = file_get_contents('path/to/file.txt');

// memory and CPU intensive
$content = join('', file('path/to/file.txt'));

// Consider reading the data line by line and processing it along the way,
// to save memory
$fp = fopen('path/to/file.txt', 'r');
while($line = fget($fp)) {
    // process a line
}
fclose($fp);

?>

Always use file_get_contents() to get the content of a file as a string. Consider using readfile() to echo the content directly to the output.

See also file_get_contents and file.

9.282.1. Suggestions

  • Use file_get_contents() instead of implode(file()) to read the whole file at once.
  • Use readfile() to echo the content to stdout at once.
  • Use fopen() to read the lines one by one, generator style.
Short name Performances/JoinFile
Rulesets Performances
Severity Minor
Time To Fix Quick (30 mins)
Examples WordPress, SPIP, ExpressionEngine, PrestaShop

9.283. Keep Files Access Restricted

Avoid using 0777 as file or directory mode. In particular, setting a file or a directory to 0777 (or universal read-write-execute) may lead to security vulnerabilities, as anything on the server may read, write and even execute

File mode may be changed using the chmod() function, or at directory creation, with mkdir().

<?php

file_put_contents($file, $content);

// this file is accessible to the current user, and to his group, for reading and writing.
chmod($file, 0550);

// this file is accessible to everyone
chmod($file, 0777);

?>

By default, this analysis report universal access (0777). It is possible to make this analysis more restrictive, by providing more forbidden modes in the filePrivileges parameter. For example : 511,510,489. Only use a decimal representation.

See also Mkdir Default and Least Privilege Violation.

9.283.1. Suggestions

  • Set the file mode to a level of restriction as low as possible.
Name Default Type Description
filePrivileges 0777 string List of forbidden file modes (comma separated).
Short name Security/KeepFilesRestricted
Rulesets Security
Severity Minor
Time To Fix Quick (30 mins)

9.284. Large Try Block

Try block should enclosing only the expression that may emit an exception.

When writing large blocks of code in a try, it becomes difficult to understand where the expression is coming from. Large blocks may also lead to catch multiples exceptions, with a long list of catch clause.

In particular, the catch clause will resume the execution without knowing where the try was interrupted : there are no indication of achievement, even partial. In fact, catching an exception signals a very dirty situation.

<?php

// try is one expression only
try {
    $database->query($query);
} catch (DatabaseException $e) {
    // process exception
}

// Too many expressions around the one that may actually emit the exception
try {
    $SQL = build_query($arguments);
    $database = new Database($dsn);
    $database->setOption($options);
    $statement = $database->prepareQuery($SQL);
    $result = $statement->query($query);
} catch (DatabaseException $e) {
    // process exception
}

?>

This analysis reports try blocks that are 5 lines or more. This threshold may be configured with the directive tryBlockMaxSize. Catch clause, and finally are not considered here.

9.284.1. Suggestions

  • Reduce the amount of code in the block, by moving it before and after
Name Default Type Description
tryBlockMaxSize 5 integer Maximal number of expressions in the try block.
Short name Exceptions/LargeTryBlock
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.285. List Short Syntax

Usage of short syntax version of list().

<?php

// PHP 7.1 short list syntax
// PHP 7.1 may also use key => value structures with list
[$a, $b, $c] = ['2', 3, '4'];

// PHP 7.0 list syntax
list($a, $b, $c) = ['2', 3, '4'];

?>
Short name Php/ListShortSyntax
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.1 and more recent
Severity Major
Time To Fix Quick (30 mins)

9.286. List With Appends

List() behavior has changed in PHP 7.0 and it has impact on the indexing when list is used with the [] operator.

<?php

$x = array();
list($x[], $x[], $x[]) = [1, 2, 3];

print_r($x);

?>

In PHP 7.0, results are ::

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
)

In PHP 5.6, results are ::

Array
(
    [0] => 3
    [1] => 2
    [2] => 1
)

9.286.1. Suggestions

  • Refactor code to avoid using append in a list() call
Short name Php/ListWithAppends
Rulesets CompatibilityPHP70
Severity Minor
Time To Fix Slow (1 hour)

9.287. List With Keys

Setting keys when using list() is a PHP 7.1 feature.

<?php

// PHP 7.1 and later only
list('a' => $a, 'b' => $b) = ['b' => 1, 'c' => 2, 'a' => 3];

?>
Short name Php/ListWithKeys
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.1 and more recent
Severity Major
Time To Fix Quick (30 mins)

9.288. List With Reference

Support for references in list calls is not backward compatible with older versions of PHP. The support was introduced in PHP 7.3.

<?php

$array = [1,2,3];

[$c, &$d, $e] = $a;

$d++;
$c++;
print_r($array);
/*
displays
Array
(
    [0] => 1  // Not a reference to $c, unchanged
    [1] => 3  // Reference from $d
    [2] => 3
)
*/
?>

See also list() Reference Assignment.

9.288.1. Suggestions

  • Avoid using references in list for backward compatibility
Short name Php/ListWithReference
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.3 and more recent
Severity Major
Time To Fix Slow (1 hour)

9.289. Locally Unused Property

Those properties are defined in a class, and this class doesn’t have any method that makes use of them.

While this is syntactically correct, it is unusual that defined resources are used in a child class. It may be worth moving the definition to another class, or to move accessing methods to the class.

<?php

class foo {
    public $unused, $used;// property $unused is never used in this class

    function bar() {
        $this->used++; // property $used is used in this method
    }
}

class foofoo extends foo {
    function bar() {
        $this->unused++; // property $unused is used in this method, but defined in the parent class
    }
}

?>

9.289.1. Suggestions

  • Move the property definition to the child classes
  • Move some of the child method, using the property, to the parent class
Short name Classes/LocallyUnusedProperty
Rulesets Dead code
Severity Minor
Time To Fix Slow (1 hour)

9.290. Logical Mistakes

Avoid logical mistakes within long expressions.

Sometimes, the logic is not what it seems. It is important to check the actual impact of every part of the logical expression. Do not hesitate to make a table with all possible cases. If those cases are too numerous, it may be time to rethink the whole expression.

<?php

// Always true
if ($a != 1 || $a != 2) { }

// $a == 1 is useless
if ($a == 1 || $a != 2) {}

// Always false
if ($a == 1 && $a == 2) {}

// $a != 2 is useless
if ($a == 1 && $a != 2) {}

?>

Based on article from Andrey Karpov Logical Expressions in C/C++. Mistakes Made by Professionals

9.290.1. Suggestions

  • Change the expressions for them to have a real meaning
Short name Structures/LogicalMistakes
Rulesets Analyze, CI-checks
Severity Critical
Time To Fix Quick (30 mins)
Examples Dolibarr, Cleverstyle

9.291. Logical Operators Favorite

PHP has two sets of logical operators : letters (and, or, xor) and chars (&&, ||, ^).

The analyzed code has less than 10% of one of the two sets : for consistency reasons, it is recommended to make them all the same.

Warning : the two sets of operators have different precedence levels. Using and or && is not exactly the same, especially and not only, when assigning the results to a variable.

<?php

$a1 = $b and $c;
$a1 = $b and $c;
$a1 = $b and $c;
$a1 = $b or $c;
$a1 = $b OR $c;
$a1 = $b and $c;
$a1 = $b and $c;
$a1 = $b and $c;
$a1 = $b or $c;
$a1 = $b OR $c;
$a1 = $b ^ $c;

?>

Using and or && are also the target of other analysis.

See also Logical Operators and Operators Precedence.

9.291.1. Suggestions

  • Pick a favorite, and enforce it
Short name Php/LetterCharsLogicalFavorite
Rulesets Top10

9.292. Logical Should Use Symbolic Operators

Logical operators come in two flavors : and / &&, || / or, ^ / xor. However, they are not exchangeable, as && and and have different precedence.

<?php

// Avoid lettered operator, as they have lower priority than expected
$a = $b and $c;
// $a === 3 because equivalent to ($a = $b) and $c;

// safe way to write the above :
$a = ($b and $c);

$a = $b && $c;
// $a === 1

?>

It is recommended to use the symbol operators, rather than the letter ones.

See also Logical Operators.

9.292.1. Suggestions

  • Change the letter operators to the symbol one : and => &&, or => ||, xor => ^. Review the new expressions as processing order may have changed.
  • Add parenthesis to make sure that the order is the expected one
Short name Php/LogicalInLetters
Rulesets Analyze, Suggestions, Top10, php-cs-fixable, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP no-letter-logical
Examples Cleverstyle, OpenConf

9.293. Logical To in_array

Multiples exclusive comparisons may be replaced by in_array().

in_array() makes the alternatives more readable, especially when the number of alternatives is large. In fact, the list of alternative may even be set in a variable, and centralized for easier management.

Even two ‘or’ comparisons are slower than using a in_array() call. More calls are even slower than just two. This is a micro-optimisation : speed gain is low, and marginal. Code centralisation is a more significant advantage.

<?php

// Set the list of alternative in a variable, property or constant.
$valid_values = array(1, 2, 3, 4);
if (in_array($a, $valid_values) ) {
    // doSomething()
}

if ($a == 1 || $a == 2 || $a == 3 || $a == 4) {
    // doSomething()
}

// in_array also works with strict comparisons
if (in_array($a, $valid_values, true) ) {
    // doSomething()
}

if ($a === 1 || $a === 2 || $a === 3 || $a === 4) {
    // doSomething()
}

?>

See also in_array().

9.293.1. Suggestions

  • Replace the list of comparisons with a in_array() call on an array filled with the various values
  • Replace the list of comparisons with a isset() call on a hash whose keys are the various values
Short name Performances/LogicalToInArray
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Precision Very high
Examples Zencart

9.294. Lone Blocks

Any grouped code without a commanding structure is useless.

Blocks are compulsory when defining a structure, such as a class or a function. They are most often used with flow control instructions, like if then or switch.

Blocks are also valid syntax that group several instructions together, though they have no effect at all, except confuse the reader. Most often, it is a ruin from a previous flow control instruction, whose condition was removed or commented. They should be removed.

<?php

    // Lone block
    //foreach($a as $b)
    {
        $b++;
    }
?>

9.294.1. Suggestions

  • Remove the useless curly brackets
Short name Structures/LoneBlock
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples ThinkPHP, Tine20

9.295. Long Arguments

Long arguments should be put in variable, to preserve readability.

When literal arguments are too long, they break the hosting structure by moving the next argument too far on the right. Whenever possible, long arguments should be set in a local variable to keep the readability.

<?php

// Now the call to foo() is easier to read.
$reallyBigNumber = <<<BIGNUMBER
123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
BIGNUMBER
foo($reallyBigNumber, 2, '12345678901234567890123456789012345678901234567890');

// where are the next arguments ?
foo('123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890', 2, '123456789012345678901234567890123456789012345678901234567890');

// This is still difficult to read
foo(<<<BIGNUMBER
123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
BIGNUMBER
, 2, '123456789012345678901234567890123456789012345678901234567890');

?>

Literal strings and heredoc strings, including variables, that are over 50 chars longs are reported here.

9.295.1. Suggestions

  • Put the long arguments in a separate variable, and use the variable in the second expression, reducing its total length
Name Default Type Description
codeTooLong 100 integer Minimum size of a functioncall or a methodcall to be considered too long.
Short name Structures/LongArguments
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples Cleverstyle, Contao

9.296. Lost References

Either avoid references, or propagate them correctly.

When assigning a referenced variable with another reference, the initial reference is lost, while the intend was to transfer the content.

<?php

function foo(&$lostReference, &$keptReference)
{
    $c = 'c';

    // $lostReference was a reference, but now, it is another
    $lostReference =& $c;
    // $keptReference was a reference : now it contains the actual value
    $keptReference = $c;
}

$bar = 'bar';
$bar2 = 'bar';
foo($bar, $bar2);

//displays bar c, instead of bar bar
print $bar. ' '.$bar2;

?>

Do not reassign a reference with another reference. Assign new content to the reference to change its value.

9.296.1. Suggestions

  • Always assign new value to an referenced argument, and don’t reassign a new reference
Short name Variables/LostReferences
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)
Examples WordPress

9.297. Magic Visibility

The class magic methods must have public visibility and cannot be static.

<?php

class foo{
    // magic method must bt public and non-static
    public static function __clone($name) {    }

    // magic method can't be private
    private function __get($name) {    }

    // magic method can't be protected
    private function __set($name, $value) {    }

    // magic method can't be static
    public static function __isset($name) {    }
}

?>

See also Magic methods.

Short name Classes/toStringPss
Rulesets CompatibilityPHP70
Php Version With PHP 5.4 and older
Severity Major
Time To Fix Quick (30 mins)

9.298. Make Global A Property

Calling global (or $GLOBALS) in methods is slower and less testable than setting the global to a property, and using this property.

Using properties is slightly faster than calling global or $GLOBALS, though the gain is not important.

Setting the property in the constructor (or in a factory), makes the class easier to test, as there is now a single point of configuration.

<?php

// Wrong way
class fooBad {
    function x() {
        global $a;
        $a->do();
        // Or $GLOBALS['a']->do();
    }
}

class fooGood {
    private $bar = null;

    function __construct() {
        global $bar;
        $this->bar = $bar;
        // Even better, do this via arguments
    }

    function x() {
        $this->a->do();
    }
}

?>

9.298.1. Suggestions

  • Avoid using global variables, and use properties instead
  • Remove the usage of these global variables
Short name Classes/MakeGlobalAProperty
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)

9.299. Make Magic Concrete

Speed up execution by replacing magic calls by concrete properties.

Magic properties are managed dynamically, with __get``and ``__set. They replace property access by a methodcall, and they are much slower than the first.

When a property name is getting used more often, it is worth creating a concrete property, and skip the method call. The threshold for ‘magicMemberUsage’ is 1, by default.

<?php

class x {
    private $values = array('a' => 1,
                            'b' => 2);

    function __get($name) {
        return $this->values[$name] ?? '';
    }
}

$x = new x();
// Access to 'a' is repeated in the code, at least 'magicMemberUsage' time (cf configuration below)
echo $x->a;

?>

See also Memoize MagicCall.

9.299.1. Suggestions

  • Make frequently used properties concrete; keep the highly dynamic as magic
Name Default Type Description
magicMemberUsage 1 integer Minimal number of magic member usage across the code, to trigger a concrete property.
Short name Classes/MakeMagicConcrete
Rulesets Performances
Severity Minor
Time To Fix Quick (30 mins)

9.300. Make One Call With Array

Avoid calling the same function several times by batching the calls with arrays.

Calling the same function to chain modifications tends to be slower than calling the same function with all the transformations at the same time. Some PHP functions accept scalars or arrays, and using the later is more efficient.

<?php

$string = 'abcdef';

//str_replace() accepts arrays as arguments
$string = str_replace( ['a', 'b', 'c'],
                       ['A', 'B', 'C'],
                       $string);

// Too many calls to str_replace
$string = str_replace( 'a', 'A', $string);
$string = str_replace( 'b', 'B', $string);
$string = str_replace( 'c', 'C', $string);

// Too many nested calls to str_replace
$string = str_replace( 'a', 'A', str_replace( 'b', 'B', str_replace( 'c', 'C', $string)));

?>

Potential replacements :

Function Replacement
str_replace() str_ireplace() substr_replace() preg_replace() preg_replace_callback() str_replace() str_replace() substr_replace() preg_replace() preg_replace_callback_array()
<?php
$subject = 'Aaaaaa Bbb';


//preg_replace_callback_array() is better than multiple preg_replace_callback :
preg_replace_callback_array(
    [
        '~[a]+~i' => function ($match) {
            echo strlen($match[0]), ' matches for a found', PHP_EOL;
        },
        '~[b]+~i' => function ($match) {
            echo strlen($match[0]), ' matches for b found', PHP_EOL;
        }
    ],
    $subject
);

$result = preg_replace_callback('~[a]+~i', function ($match) {
            echo strlen($match[0]), ' matches for a found', PHP_EOL;
        }, $subject);

$result = preg_replace_callback('~[b]+~i', function ($match) {
            echo strlen($match[0]), ' matches for b found', PHP_EOL;
        }, $subject);

//str_replace() accepts arrays as arguments
$string = str_replace( ['a', 'b', 'c'],
                       ['A', 'B', 'C'],
                       $string);

// Too many calls to str_replace
$string = str_replace( 'a', 'A');
$string = str_replace( 'b', 'B');
$string = str_replace( 'c', 'C');

?>

9.300.1. Suggestions

  • use str_replace() with arrays as arguments.
  • use preg_replace() with arrays as arguments.
  • use preg_replace_callback() for merging multiple complex calls.
Short name Performances/MakeOneCall
Rulesets Performances
Severity Major
Time To Fix Quick (30 mins)
Examples HuMo-Gen, Edusoho

9.301. Malformed Octal

Those numbers starts with a 0, so they are using the PHP octal convention. Therefore, one can’t use 8 or 9 figures in those numbers, as they don’t belong to the octal base. The resulting number will be truncated at the first erroneous figure. For example, 090 is actually 0, and 02689 is actually 22.

<?php

// A long way to write 0 in PHP 5
$a = 0890;

// A fatal error since PHP 7

?>

Also, note that very large octal, usually with more than 21 figures, will be turned into a real number and undergo a reduction in precision.

See also Integers.

Short name Type/MalformedOctal
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and older
Severity Minor
Time To Fix Instant (5 mins)

9.302. Max Level Of Nesting

Avoid nesting structures too deep, as it hurts readability.

Nesting structures are : if/then, switch, for, foreach, while, do…while. Ternary operator, try/catch are not considered a nesting structures.

Closures, and more generally, functions definitions are counted separatedly.

This analysis checks for 4 levels of nesting, by default. This may be changed by configuration.

<?php

// 5 levels of indentation
function foo() {
    if (1) {
        if (2) {
            if (3) {
                if (4) {
                    if (5) {
                        51;
                    } else {
                        5;
                    }
                } else {
                    4;
                }
            } else {
                3;
            }
        } else {
            2;
        }
    } else {
        1;
    }
}

// 2 levels of indentation
function foo() {
    if (1) {
        if (2) {
            // 3 levels of indentation
            return function () {
                if (3) {
                    if (4) {
                        if (5) {
                            51;
                        } else {
                            5;
                        }
                    } else {
                        4;
                    }
                } else {
                    3;
                }
            }
        } else {
            2;
        }
    } else {
        1;
    }
}


?>

9.302.1. Suggestions

  • Refactor code to avoid nesting
  • Export some nested blocks to an external method or function
Name Default Type Description
maxLevel 4 integer Maximum level of nesting for control flow structures in one scope.
Short name Structures/MaxLevelOfIdentation
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.303. Mbstring Third Arg

Some mbstring functions use the third argument for offset, not for encoding.

Those are the following functions :

<?php

// Display BC
echo mb_substr('ABC', 1 , 2, 'UTF8');

// Yields Warning: mb_substr() expects parameter 3 to be int, string given
// Display 0 (aka, substring from 0, for length (int) 'UTF8' => 0)
echo mb_substr('ABC', 1 ,'UTF8');

?>

See also mb_substr() manual pages.

9.303.1. Suggestions

  • Add a third argument
  • Use the default encoding (aka, omit both third AND fourth argument)
Short name Structures/MbstringThirdArg
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.304. Mbstring Unknown Encoding

The encoding used is not known to the ext/mbstring extension.

This analysis takes in charge all mbstring encoding and aliases. The full list of supported mbstring encoding is available with mb_list_encodings(). Each encoding alias is available with mb_encoding_aliases().

<?php

// Invalid encoding
$str = mb_strtolower($str, 'utf_8');

// Valid encoding
$str = mb_strtolower($str, 'utf8');
$str = mb_strtolower($str, 'UTF8');
$str = mb_strtolower($str, 'UTF-8');

?>

See also ext/mbstring.

9.304.1. Suggestions

  • Use a valid mbstring encoding
Short name Structures/MbstringUnknownEncoding
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.305. Memoize MagicCall

Cache calls to magic methods in local variable. Local cache is faster than calling again the magic method as soon as the second call, provided that the value hasn’t changed.

__get is slower, as it turns a simple member access into a full method call.

<?php

class x {
    private $values = array();

    function __get($name) {
        return $this->values[$name];
    }
    // more code to set values to this class
}

function foo(x $b) {
    $a = $b->a;
    $c = $b->c;

    $d = $c;     // using local cache, no new access to $b->__get($name)
    $e = $b->a;  // Second access to $b->a, through __get
}

function bar(x $b) {
    $a = $b->a;
    $c = $b->c;

    $b->bar2(); // this changes $b->a and $b->c, but we don't see it

    $d = $b->c;
    $e = $b->a;  // Second access to $b->a, through __get
}

?>

The caching is not possible if the processing of the object changes the value of the property.

See also __get performance questions with PHP, Make Magic Concrete and Benchmarking magic.

9.305.1. Suggestions

  • Cache the value in a local variable, and reuse that variable
  • Make the property concrete in the class, so as to avoid __get() altogether
Name Default Type Description
minMagicCallsToGet 2 integer Minimal number of calls of a magic property to make it worth locally caching.
Short name Performances/MemoizeMagicCall
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.306. Merge If Then

Two successive if/then into one, by merging the two conditions.

<?php

// two merge conditions
if ($a == 1 && $b == 2) {
    // doSomething()
}

// two distinct conditions
// two nesting
if ($a == 1) {
    if ($b == 2) {
        // doSomething()
    }
}

?>

9.306.1. Suggestions

  • Merge the two structures into one
Short name Structures/MergeIfThen
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.307. Method Collision Traits

Two or more traits are included in the same class, and they have methods collisions.

Those collisions should be solved with a use expression. When they are not, PHP stops execution with a fatal error : Trait method M has not been applied, because there are collisions with other trait methods on C.

<?php

trait A {
    public function A() {}
    public function M() {}
}

trait B {
    public function B() {}
    public function M() {}
}

class C {
    use  A, B;
}

class D {
    use  A, B{
        B::M insteadof A;
    };
}

?>

The code above lints, but doesn’t execute.

See also Traits.

Short name Traits/MethodCollisionTraits
Rulesets Analyze, LintButWontExec
Severity Critical
Time To Fix Quick (30 mins)

9.308. Method Could Be Private Method

The following methods are never used outside their class of definition. Given the analyzed code, they could be set as private.

<?php

class foo {
    public function couldBePrivate() {}
    public function cantdBePrivate() {}

    function bar() {
        // couldBePrivate is used internally.
        $this->couldBePrivate();
    }
}

class foo2 extends foo {
    function bar2() {
        // cantdBePrivate is used in a child class.
        $this->cantdBePrivate();
    }
}

//couldBePrivate() is not used outside
$foo = new foo();

//cantdBePrivate is used outside the class
$foo->cantdBePrivate();

?>

Note that dynamic properties (such as $x->$y) are not taken into account.

Short name Classes/CouldBePrivateMethod
Rulesets ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.309. Method Could Be Static

A method that doesn’t make any usage of $this could be turned into a static method.

While static methods are usually harder to handle, recognizing the static status is a first step before turning the method into a standalone function.

<?php

class foo {
    static $property = 1;

    // legit static method
    static function staticMethod() {
        return self::$property;
    }

    // This is not using $this, and could be static
    function nonStaticMethod() {
        return self::$property;
    }

    // This is not using $this nor self, could be a standalone function
    function nonStaticMethod() {
        return self::$property;
    }
}

?>

9.309.1. Suggestions

  • Make the method static
  • Make the method a standalone function
  • Make use of $this in the method : may be it was forgotten.
Short name Classes/CouldBeStatic
Rulesets none
Severity Minor
Time To Fix Quick (30 mins)
Examples FuelCMS, ExpressionEngine

9.310. Method Signature Must Be Compatible

Make sure methods signature are compatible.

PHP generates the infamous Fatal error at execution : Declaration of FooParent\:\:Bar() must be compatible with FooChildren\:\:Bar()

<?php

class x {
    function xa() {}
}

class xxx extends xx {
    function xa($a) {}
}

?>

9.310.1. Suggestions

  • Fix the child class method() signature.
  • Fix the parent class method() signature, after checking that it won’t affect the other children.
Short name Classes/MethodSignatureMustBeCompatible
Rulesets Analyze, LintButWontExec
Severity Critical
Time To Fix Quick (30 mins)

9.311. Methodcall On New

It is possible to call a method right at object instantiation.

This syntax was added in PHP 5.4+. Before, this was not possible : the object had to be stored in a variable first.

<?php

// Data is collected
$data = data_source();

// Data is saved, but won't be reused from this databaseRow object. It may be ignored.
$result = (new databaseRow($data))->save();

// The actual result of the save() is collected and tested.
if ($result !== true) {
    processSaveError($data);
}

?>

This syntax is interesting when the object is not reused, and may be discarded

Short name Php/MethodCallOnNew
Rulesets CompatibilityPHP53
Php Version With PHP 5.4 and more recent
Severity Major
Time To Fix Quick (30 mins)

9.312. Methods Without Return

List of all the function, closures, methods that have no explicit return.

Functions that hold the void return type are omitted.

<?php

// With return null : Explicitly not returning
function withExplicitReturn($a = 1) {
    $a++;
    return null;
}

// Without indication
function withoutExplicitReturn($a = 1) {
    $a++;
}

// With return type void : Explicitly not returning
function withExplicitReturnType($a = 1) : void {
    $a++;
}

?>

See also return.

9.312.1. Suggestions

  • Add the returntype ‘void’ to make this explicit behavior
Short name Functions/WithoutReturn
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Precision Very high

9.313. Minus One On Error

Some PHP native functions return -1 on error. They also return 1 in case of success, and 0 in case of failure. This leads to confusions.

In case the native function is used as a condition without explicit comparison, PHP type cast the return value to a boolean. In this case, -1 and 1 are both converted to true, and the condition applies. This means that an error situation is mistaken for a successful event.

<?php

// Proper check of the return value
if (openssl_verify($data, $signature, $public) === 1) {
    $this->loginAsUser($user);
}

// if this call fails, it returns -1, and is confused with true
if (openssl_verify($data, $signature, $public)) {
    $this->loginAsUser($user);
}
?>

This analysis searches for if/then structures, ternary operators inside while() / do…`while() <https://www.php.net/manual/en/control-structures.while.php>`_ loops.

See also Can you spot the vulnerability? (openssl_verify) and Incorrect Signature Verification.

9.313.1. Suggestions

  • Compare explicitly the return value to 1
Short name Security/MinusOneOnError
Rulesets Security
Severity Critical
Time To Fix Instant (5 mins)

9.314. Mismatch Parameter And Type

When the name of the parameter contradicts the type of the parameter.

This is mostly semantics, so it will affect the coder and the auditor of the code. PHP is immune to those errors.

<?php

// There is a discrepancy between the typehint and the name of the variable
function foo(int $string) { }

// The parameter name is practising coding convention typehints
function bar(int $int) { }

?>

9.314.1. Suggestions

  • Synch the name of the parameter and the typehint.
Short name Functions/MismatchParameterAndType
Rulesets Analyze, Semantics
Severity Minor
Time To Fix Quick (30 mins)

9.315. Mismatch Parameter Name

Parameter name change in overwritten method. This may lead to errors when using PHP 8.0 named arguments.

PHP use the name of the parameter in the method whose code is executed. When the name change between the method and the overwritten method, the consistency is broken.

<?php

class x {
    function getValue($name) {}
}

class y extends x {
    // consistent with the method above
    function getValue($name) {}
}

class z extends x {
    // inconsistent with the method above
    function getValue($label) {}
}

?>

9.315.1. Suggestions

  • Make sure all the names are the same, between methods
Short name Functions/MismatchParameterName
Rulesets Analyze, CompatibilityPHP80
Severity Minor
Time To Fix Quick (30 mins)

9.316. Mismatch Properties Typehints

Properties must match within the same family.

When a property is declared both in a parent class, and a child class, they must have the same type. The same type includes a possible null value.

This doesn’t apply to private properties, which are only visible locally.

<?php

// property $p is declared as an object of type a class x {

protected A $p;

}

// property $p is declared again, this time without a type class a extends x {

protected $p;

}

This code will lint, but not execute.

9.316.1. Suggestions

  • Remove some of the property declarations, and only keep it in the highest ranking parent
  • Match the typehints of the property declarations
  • Make the properties private
  • Remove the child class (or the parent class)
Short name Classes/MismatchProperties
Rulesets Analyze, LintButWontExec, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.317. Mismatch Type And Default

The argument typehint and its default value don’t match.

The code may lint and load, and even work when the arguments are provided. Though, PHP won’t eventually execute it.

Most of the mismatch problems are caught by PHP at linting time. It displays the following error message : ‘Argument 1 passed to foo() must be of the type integer, string given’.

The default value may be a constant (normal or class constant) : as such, PHP might find its value only at execution time, from another include. As such, PHP doesn’t report anything about the situation at compile time.

The default value may also be a constant scalar expression : since PHP 7, some of the simple operators such as +, -, , %, `* <https://www.php.net/manual/en/language.operators.arithmetic.php>`_, etc. are available to build default values. Among them, the ternary operator and Coalesce. Again, those expression may be only evaluated at execution time, when the value of the constants are known.

<?php

// bad definition : the string is actually an integer
const STRING = 3;

function foo(string $s = STRING) {
    echo $s;
}

// works without problem
foo('string');

// Fatal error at compile time
foo();

// Fail only at execution time (missing D), and when default is needed
function foo2(string $s = D ? null : array()) {
    echo $s;
}

?>

PHP reports typehint and default mismatch at compilation time, unless there is a static expression that can’t be resolved within the compiled file : then it is checked only at runtime, leading to a Fatal error.

See also Type declarations.

9.317.1. Suggestions

  • Match the typehint with the default value
  • Do not rely on PHP type juggling to change the type on the fly
Short name Functions/MismatchTypeAndDefault
Rulesets Analyze, LintButWontExec, Typechecks
Severity Critical
Time To Fix Slow (1 hour)

9.318. Mismatched Default Arguments

Arguments are relayed from one method to the other, and the arguments have different default values.

Although it is possible to have different default values, it is worth checking why this is actually the case.

<?php

function foo($a = null, $b = array() ) {
    // foo method calls directly bar.
    // When argument are provided, it's OK
    // When argument are omited, the default value is not the same as the next method
    bar($a, $b);
}

function bar($c = 1, $d = array() ) {

}

?>

9.318.1. Suggestions

  • Synchronize default values to avoid surprises
  • Drop some of the default values
Short name Functions/MismatchedDefaultArguments
Rulesets Analyze, Typechecks
Severity Minor
Time To Fix Quick (30 mins)
Examples SPIP

9.319. Mismatched Ternary Alternatives

A ternary operator should yield the same type on both branches.

Ternary operator applies a condition, and yield two different results. Those results will then be processed by code that expects the same types. It is recommended to match the types on both branches of the ternary operator.

<?php

// $object may end up in a very unstable state
$object = ($type == 'Type') ? new $type() : null;

//same result are provided by both alternative, though process is very different
$result = ($type == 'Addition') ? $a + $b : $a * $b;

//Currently, this is omitted
$a = 1;
$result = empty($condition) ? $a : 'default value';
$result = empty($condition) ? $a : getDefaultValue();

?>

9.319.1. Suggestions

  • Use compatible data type in both branch of the alternative
  • Turn the ternary into a if/then, with different processing
Short name Structures/MismatchedTernary
Rulesets Analyze, Suggestions
Severity Major
Time To Fix Quick (30 mins)
Examples phpadsnew, OpenEMR

9.320. Mismatched Typehint

Relayed arguments don’t have the same typehint.

Typehint acts as a filter method. When an object is checked with a first class, and then checked again with a second distinct class, the whole process is always false : $a can’t be of two different classes at the same time.

<?php

// Foo() calls bar()
function foo(A $a, B $b) {
    bar($a, $b);
}

// $a is of A typehint in both methods, but
// $b is of B then BB typehing
function bar(A $a, BB $b) {

}

?>

Note : This analysis currently doesn’t check generalisation of classes : for example, when B is a child of BB, it is still reported as a mismatch.

9.320.1. Suggestions

  • Ensure that the default value match the expected typehint.
Short name Functions/MismatchedTypehint
Rulesets Analyze, Typechecks
Severity Major
Time To Fix Quick (30 mins)
Precision High
Examples WordPress

9.321. Missing Abstract Method

Abstract methods must have a non-abstract version for the class to be complete. A class that is missing one abstract definition cannot be instantiated.

<?php

// This is a valid definition
class b extends a {
    function foo() {}
    function bar() {}
}

// This compiles, but will emit a fatal error if instantiated
class c extends a {
    function bar() {}
}

// This illustration lint but doesn't run.
// moving this class at the beginning of the code will make lint fail
abstract class a {
    abstract function foo() ;
}

?>

See also Classes Abstraction.

9.321.1. Suggestions

  • Implement the missing methods
  • Remove the partially implemented class
  • Mark the partially implemented class abstract
Short name Classes/MissingAbstractMethod
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.322. Missing Cases In Switch

It seems that some cases are missing in this switch structure.

When comparing two different switch() structures, it appears that some cases are missing in one of them. The set of cases are almost identical, but one of the values are missing.

Switch() structures using strings as literals are compared in this analysis. When the discrepancy between two lists is below 25%, both switches are reported.

<?php

// This switch operates on a, b, c, d and default
switch($a) {
    case 'a': doSomethingA(); break 1;
    case 'b': doSomethingB(); break 1;
    case 'c': doSomethingC(); break 1;
    case 'd': doSomethingD(); break 1;
    default: doNothing();
}

// This switch operates on a, b, d and default
switch($o->p) {
    case 'a': doSomethingA(); break 1;
    case 'b': doSomethingB(); break 1;

    case 'd': doSomethingD(); break 1;
    default: doNothing();
}

?>

In the example, one may argue that the ‘c’ case is actually handled by the ‘default’ case. Otherwise, business logic may request that omission.

9.322.1. Suggestions

  • Add the missing cases
  • Add comments to mention that missing cases are processed in the default case
Short name Structures/MissingCases
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples Tikiwiki

9.323. Missing Include

The included files doesn’t exists in the repository. The inclusions target a files that doesn’t exist.

The analysis works with every type of inclusion : include(), require(), include_once() and require_once(). It also works with parenthesis when used as parameter delimiter.

The analysis doesn’t take into account include_path. This may yield false positives.

<?php

include 'non_existent.php';

// variables are not resolved. This won't be reported.
require ($path.'non_existent.php');

?>

Missing included files may lead to a fatal error, a warning or other error later in the execution.

Name Default Type Description
constant_or_variable_name 100 string Literal value to be used when including files. For example, by configuring ‘Files_MissingInclude[“HOME_DIR”] = “/tmp/myDir/”;’, then ‘include HOME_DIR . “my_class.php”; will be actually be used as ‘/tmp/myDir/my_class.php’. Constants must be configured with their correct case. Variable must be configured with their initial ‘$’. Configure any number of variable and constant names.
Short name Files/MissingInclude
Rulesets Analyze
Severity Critical
Time To Fix Instant (5 mins)

9.324. Missing New ?

This functioncall looks like a class instantiation that is missing the new keyword.

Any function definition was found for that function, but a class with that name was. New is probably missing.

<?php

// Functioncall
$a = foo();

// Class definition
class foo {}
// Function definition
function foo {}


// Functioncall
$a = BAR;

// Function definition
class bar {}
// Constant definition
const BAR = 1;


?>

9.324.1. Suggestions

  • Add the new
  • Rename the class to distinguish it from the function
  • Rename the function to distinguish it from the class
Short name Structures/MissingNew
Rulesets Analyze
Severity Critical
Time To Fix Instant (5 mins)

9.325. Missing Parenthesis

Add parenthesis to those expression to prevent bugs.

<?php

// Missing some parenthesis!!
if (!$a instanceof Stdclass) {
    print Not\n;
} else {
    print Is\n;
}

// Could this addition be actually
$c = -$a + $b;

// This one ?
$c = -($a + $b);

?>

See also Operators Precedence.

Short name Structures/MissingParenthesis
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Instant (5 mins)

9.326. Missing Returntype In Method

The specified typehints are not sufficient. The code of the method may return other types, which are not specified.

<?php

function fooSN() : ?string  {
    return shell_exec('ls -hla');
}

// shell_exec() may return null or string. Here, only string in specified for fooS, and that may lead to a Fatal error
function fooS() : string  {
    return shell_exec('ls -hla');
}

function bar() : int {
    return rand(0, 10) ? 1 : b;
}

?>

The analysis reports a method when it finds other return types than the one expected. In the case of multiple typehints, as for the last example, the PHP code may require an upgrade to PHP 8.0.

9.326.1. Suggestions

  • Update the typehint to accept more types
  • Update the code of the method to fit the expected returntype
Short name Typehints/MissingReturntype
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Precision Very high

9.327. Missing Typehint

No typehint was found for this parameter, or as a return type for the function.

void is considered a specified typehint, and is not reported here.

<?php

function foo($no_typehint) : void {}

function no_return_type() {}

?>

See also Type Declaration.

9.327.1. Suggestions

Short name Functions/MissingTypehint
Rulesets Typechecks
Severity Minor
Time To Fix Quick (30 mins)

9.328. Mistaken Concatenation

A unexpected structure is built for initialization. It may be a typo that creates an unwanted expression.

<?php

// This 'cd' is unexpected. Isn't it 'c', 'd' ?
$array = array('a', 'b', 'c'. 'd');
$array = array('a', 'b', 'c', 'd');

// This 4.5 is unexpected. Isn't it 4, 5 ?
$array = array(1, 2, 3, 4.5);
$array = array(1, 2, 3, 4, 5);

?>
Short name Arrays/MistakenConcatenation
Rulesets Coding Conventions
Severity Major
Time To Fix Instant (5 mins)

9.329. Mixed Concat And Interpolation

Mixed usage of concatenation and string interpolation is error prone. It is harder to read, and leads to overlooking the concatenation or the interpolation.

<?php

// Concatenation string
$a = $b . 'c' . $d;

// Interpolation strings
$a = {$b}c{$d};   // regular form
$a = {$b}c$d;     // irregular form

// Mixed Concatenation and Interpolation string
$a = {$b}c . $d;
$a = $b . c$d;
$a = $b . c{$d};

// Mixed Concatenation and Interpolation string with constant
$a = {$b}c . CONSTANT;

?>

Fixing this issue has no impact on the output. It makes code less error prone.

There are some situations where using concatenation are compulsory : when using a constant, calling a function, running a complex expression or make use of the escape sequence. You may also consider pushing the storing of such expression in a local variable.

9.329.1. Suggestions

  • Only use one type of variable usage : either interpolation, or concatenation
Short name Structures/MixedConcatInterpolation
Rulesets Coding Conventions, Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples SuiteCrm, Edusoho

9.330. Mixed Keys Arrays

Avoid mixing constants and literals in array keys.

When defining default values in arrays, it is recommended to avoid mixing constants and literals, as PHP may mistake them and overwrite the previous with the latter.

Either switch to a newer version of PHP (5.5 or newer), or make sure the resulting array hold the expected data. If not, reorder the definitions.

<?php

const ONE = 1;

$a = [ 1   => 2,
       ONE => 3];

?>

9.330.1. Suggestions

  • Use only literals or constants when building the array
Short name Arrays/MixedKeys
Rulesets CompatibilityPHP53, CompatibilityPHP54
Php Version With PHP 5.6 and more recent
Severity Minor
Time To Fix Slow (1 hour)

9.331. Mkdir Default

mkdir() gives universal access to created folders, by default. It is recommended to gives limited set of rights (0755, 0700), or to explicitly set the rights to 0777.

<?php

// By default, this dir is 777
mkdir('/path/to/dir');

// Explicitely, this is wanted. It may also be audited easily
mkdir('/path/to/dir', 0777);

// This dir is limited to the current user.
mkdir('/path/to/dir', 0700);

?>

See also Why 777 Folder Permissions are a Security Risk.

9.331.1. Suggestions

  • Always use the lowest possible privileges on folders
  • Don’t use the PHP default : at least, make it explicit that the ‘universal’ rights are voluntary
Short name Security/MkdirDefault
Rulesets Security
Severity Major
Time To Fix Quick (30 mins)
Examples Mautic, OpenEMR

9.332. Modernize Empty With Expression

empty() accepts expressions as argument. This feature was added in PHP 5.5.

There is no need to store the expression in a variable before testing, unless it is reused later.

<?php

// PHP 5.5+ empty() usage
if (empty(foo($b . $c))) {
    doSomethingWithoutA();
}

// Compatible empty() usage
$a = foo($b . $c);
if (empty($a)) {
    doSomethingWithoutA();
}

// $a2 is reused, storage is legit
$a2 = strtolower($b . $c);
if (empty($a2)) {
    doSomething();
} else {
    echo $a2;
}

?>

See also empty() and empty() supports arbitrary expressions.

9.332.1. Suggestions

  • Avoid the temporary variable, and use directly empty()
Short name Structures/ModernEmpty
Rulesets Analyze
Php Version With PHP 5.5 and more recent
Severity Minor
Time To Fix Quick (30 mins)

9.333. Modified Typed Parameter

Reports modified parameters, which have a non-scalar typehint. Such variables should not be changed within the body of the method. Unlike typed properties, which always hold the expected type, typed parameters are only garanteed type at the beginning of the method block.

<?php

class x {

    function foo(Y $y) {
        // $y is type Y

        // A cast version of $y is stored into $yAsString. $y is untouched.
        $yAsString = (string) $y;

        // $y is of type 'int', now.
        $y = 1;

        // Some more code

        // display the string version.
        echo $yAsString;
        // so, Y $y is now raising an error
        echo $y->name;
    }
}

?>

This problem doesn’t apply to scalar types : by default, PHP pass scalar parameters by value, not by reference. Class types are always passed by reference.

This problem is similar to `Classes/DontUnsetProperties`_ : the static specification of the property may be unset, leading to confusing ‘undefined property’, while the class hold the property definition.

9.333.1. Suggestions

  • Use different variable names when convertir a parameter to a different type.
  • Only use methods and properties calls on a typed parameter.
Short name Functions/ModifyTypedParameter
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.334. Multiple Alias Definitions

Some aliases are representing different classes across the repository. This leads to potential confusion.

Across an application, it is recommended to use the same namespace for one alias. Failing to do this lead to the same keyword to represent different values in different files, with different behavior. Those are hard to find bugs.

<?php

namespace A {
    use d\d; // aka D
}

// Those are usually in different files, rather than just different namespaces.

namespace B {
    use b\c as D; // also D. This could be named something else
}

?>

9.334.1. Suggestions

  • Give more specific names to classes
  • Use an alias ‘use AB ac BC’ to give locally another name
Short name Namespaces/MultipleAliasDefinitions
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples ChurchCRM, Phinx

9.335. Multiple Alias Definitions Per File

Avoid aliasing the same name with different aliases. This leads to confusion.

<?php

// first occurrence
use name\space\ClasseName;

// when this happens, several other uses are mentionned

// name\space\ClasseName has now two names
use name\space\ClasseName as anotherName;

?>

See also Namespaces/MultipleAliasDefinition.

Short name Namespaces/MultipleAliasDefinitionPerFile
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Slow (1 hour)

9.336. Multiple Class Declarations

It is possible to declare several times the same class in the code. PHP will not mention it until execution time, since declarations may be conditional.

<?php

$a = 1;

// Conditional declaration
if ($a == 1) {
    class foo {
        function method() { echo 'class 1';}
    }
} else {
    class foo {
        function method() { echo 'class 2';}
    }
}

(new foo())->method();
?>

It is recommended to avoid declaring several times the same class in the code. The best practice is to separate them with namespaces, they are for here for that purpose. In case those two classes are to be used interchangeably, the best is to use an abstract class or an interface.

9.336.1. Suggestions

  • Store classes with different names in different namespaces
  • Change the name of the classes and give them a common interface to allow from common behavior
Short name Classes/MultipleDeclarations
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)

9.337. Multiple Classes In One File

It is regarded as a bad practice to store several classes in the same file. This is usually done to make life of __autoload() easier.

It is often unexpected to find class foo in the bar.php file. This is also the case for interfaces and traits.

<?php

// three classes in the same file
class foo {}
class bar {}
class foobar{}

?>

One good reason to have multiple classes in one file is to reduce include time by providing everything into one nice include.

See also Is it a bad practice to have multiple classes in the same file?.

9.337.1. Suggestions

  • Split the file into smaller files, one for each class
Short name Classes/MultipleClassesInFile
Rulesets Coding Conventions
Severity Minor
Time To Fix Quick (30 mins)

9.338. Multiple Constant Definition

Some constants are defined several times in your code. This will lead to a fatal error, if they are defined during the same execution.

Multiple definitions may happens at bootstrap, when the application code is collecting information about the current environment. It may also happen at inclusion time, which one set of constant being loaded, while other definition are not, avoiding conflict. Both are false positive.

<?php

// OS is defined twice.
if (PHP_OS == 'Windows') {
    define('OS', 'Win');
} else {
    define('OS', 'Other');
}

?>

9.338.1. Suggestions

  • Move the constants to a class, and include the right class based on control flow.
  • Give different names to the constants, and keep the condition close to utilisation.
  • Move the constants to an external configuration file : it will be easier to identify that those constants may change.
Short name Constants/MultipleConstantDefinition
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples Dolibarr, OpenConf

9.339. Multiple Declaration Of Strict_types

At least two declare() commands are declaring strict_types in one file. Only one is sufficient, and should be the first expression in the file.

Indeed, any strict_types set to 1 will have the final word. Setting strict_types to 0 will not revert the configuration, wherever is this call made.

<?php
declare(strict_types=1);
declare(strict_types=1);

// rest of the code

?>

See also Declare.

9.339.1. Suggestions

  • Just remove all but one of them.
Short name Php/MultipleDeclareStrict
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.340. Multiple Definition Of The Same Argument

A method’s signature is holding twice (or more) the same argument. For example, function x ($a, $a) { }.

This is accepted as is by PHP 5, and the last parameter’s value will be assigned to the variable. PHP 7.0 and more recent has dropped this feature, and reports a fatal error when linting the code.

<?php
  function x ($a, $a) { print $a; };
  x(1,2); => display 2

    // special case with a closure :
  function ($a) use ($a) { print $a; };
  x(1,2); => display 2

?>

However, this is not common programming practise : all arguments should be named differently.

See also Prepare for PHP 7 error messages (part 3).

9.340.1. Suggestions

  • Give different names to different parameters
Short name Functions/MultipleSameArguments
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Instant (5 mins)
ClearPHP all-unique-arguments

9.341. Multiple Exceptions Catch()

It is possible to have several distinct exceptions class caught by the same catch, preventing code repetition.

This is a new feature since PHP 7.1.

<?php

// PHP 7.1 and more recent
try {
    throw new someException();
} catch (Single $s) {
    doSomething();
} catch (oneType | anotherType $s) {
    processIdentically();
} finally {

}

// PHP 7.0 and older
try {
    throw new someException();
} catch (Single $s) {
    doSomething();
} catch (oneType $s) {
    processIdentically();
} catch (anotherType $s) {
    processIdentically();
} finally {

}

?>

This is a backward incompatible feature of PHP 7.1.

Short name Exceptions/MultipleCatch
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Severity Major
Time To Fix Quick (30 mins)

9.342. Multiple Identical Trait Or Interface

There is no need to use the same trait, or implements the same interface more than once.

Up to PHP 7.1 (at least), this doesn’t raise any warning. Traits are only imported once, and interfaces may be implemented as many times as wanted.

<?php

class foo {
    use t3,t3,t3;
}

class bar implements i,i,i {

}

?>

9.342.1. Suggestions

  • Remove the duplicate trait or interfaces
Short name Classes/MultipleTraitOrInterface
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)

9.343. Multiple Index Definition

Indexes that are defined multiple times in the same array.

<?php
    // Multiple identical keys
    $x = array(1 => 2,
               2 => 3,
               1 => 3);

    // Multiple identical keys (sneaky version)
    $x = array(1 => 2,
               1.1 => 3,
               true => 4);

    // Multiple identical keys (automated version)
    $x = array(1 => 2,
               3,        // This will be index 2
               2 => 4);  // this index is overwritten
?>

They are indeed overwriting each other. This is most probably a typo.

9.343.1. Suggestions

  • Review your code and check that arrays only have keys defined once.
  • Review carefully your code and check indirect values, like constants, static constants.
Short name Arrays/MultipleIdenticalKeys
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples Magento, MediaWiki

9.344. Multiple Type Variable

Avoid using the same variable with different types of data.

It is recommended to use different names for differently typed data, while processing them. This prevents errors where one believe the variable holds the former type, while it has already been cast to the later.

Incrementing variables, with math operations or concatenation, is OK : the content changes, but not the type. And casting the variable without storing it in itself is OK.

<?php

// $x is an array
$x = range('a', 'z');
// $x is now a string
$x = join('', $x);
$c = count($x); // $x is not an array anymore


// $letters is an array
$letters = range('a', 'z');
// $alphabet is a string
$alphabet = join('', $letters);

// Here, $letters is cast by PHP, but the variable is changed.
if ($letters) {
    $count = count($letters); // $letters is still an array
}

?>

9.344.1. Suggestions

  • Use a class that accepts one type of argument, and exports another type of argument.
  • Use different variable for each type of data format : $rows (for array), $list (for implode(‘’, $rows))
  • Pass the final result as argument to another method, avoiding the temporary variable
Short name Structures/MultipleTypeVariable
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples Typo3, Vanilla

9.345. Multiple Unset()

Unset() accepts multiple arguments, unsetting them one after each other. It is more efficient to call unset() once, than multiple times.

<?php

// One call to unset only
unset($a, $b, $c, $d);

// Too many calls to unset
unset($a);
unset($b);
unset($c);
unset($d);

?>

See also unset.

9.345.1. Suggestions

  • Merge all unset into one call
Short name Structures/MultipleUnset
Rulesets Suggestions, php-cs-fixable
Severity Minor
Time To Fix Quick (30 mins)

9.346. Multiple Usage Of Same Trait

The same trait is used several times. One trait usage is sufficient.

<?php

// C is used twice, and could be dropped from B
trait A { use B, C;}
trait B { use C;}

?>

PHP doesn’t raise any error when traits are included multiple times.

See also Traits.

9.346.1. Suggestions

  • Remove any multiple traits from use expressions
  • Review the class tree, and remove any trait mentioned multiple times
Short name Traits/MultipleUsage
Rulesets Suggestions
Severity Minor
Time To Fix Instant (5 mins)
Examples NextCloud

9.347. Multiples Identical Case

Some cases are defined multiple times, but only one will be processed. Check the list of cases, and remove the extra one.

Exakat tries to find the value of the case as much as possible, and ignore any dynamic cases (using variables).

<?php

const A = 1;

case ($x) {
    case 1 :
        break;
    case true:    // This is a duplicate of the previous
        break;
    case 1 + 0:   // This is a duplicate of the previous
        break;
    case 1.0 :    // This is a duplicate of the previous
        break;
    case A :      // The A constant is actually 1
        break;
    case $y  :    // This is not reported.
        break;
    default:

}
?>

9.347.1. Suggestions

  • Remove the double case
  • Change the case to another and rightful value
Short name Structures/MultipleDefinedCase
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
ClearPHP no-duplicate-case
Examples SugarCrm, ExpressionEngine

9.348. Multiply By One

Multiplying by 1 is a fancy type cast.

If it is used to type cast a value to number, then casting (integer) or (real) is clearer. This behavior may change with PHP 7.1, which has unified the behavior of all hidden casts.

<?php

// Still the same value than $m, but now cast to integer or real
$m = $m * 1;

// Still the same value than $m, but now cast to integer or real
$n *= 1;

// make typecasting clear, and merge it with the producing call.
$n = (int) $n;

?>

See also Type Juggling

9.348.1. Suggestions

  • Typecast to (int) or (float) for better readability
  • Skip useless math operation altogether
Short name Structures/MultiplyByOne
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP no-useless-math
Examples SugarCrm, Edusoho

9.349. Must Call Parent Constructor

Some PHP native classes require a call to parent::__construct() to be stable.

As of PHP 7.3, two classes currently need that call : SplTempFileObject and SplFileObject.

The error is only emitted if the class is instantiated, and a parent class is called.

<?php

class mySplFileObject extends \SplFileObject {
    public function __construct()    {
        // Forgottent call to parent::__construct()
    }
}

(new mySplFileObject())->passthru();
?>

See also Why, php? WHY???.

9.349.1. Suggestions

  • Add a call to the parent’s constructor
  • Remove the extension of the parent class
Short name Php/MustCallParentConstructor
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.350. Must Return Methods

The following methods are expected to return a value that will be used later. Without return, they are useless.

Methods that must return are : __get(), __isset(), __sleep(), __toString(), __set_state(), __invoke(), __debugInfo(). Methods that may not return, but are often expected to : __call(), __callStatic().

<?php

class foo {
    public function __isset($a) {
        // returning something useful
        return isset($this->$var[$a]);
    }

    public function __get($a) {
        $this->$a++;
        // not returning...
    }

    public function __call($name, $args) {
        $this->$name(...$args);
        // not returning anything, but that's OK
    }

}
?>

9.350.1. Suggestions

  • Add a return expression, with a valid data type
  • Remove the return typehint
Short name Functions/MustReturn
Rulesets Analyze, LintButWontExec, CI-checks
Severity Major
Time To Fix Quick (30 mins)

9.351. Named Regex

Captured subpatterns may be named, for easier reference.

From the manual : It is possible to name a subpattern using the syntax (?P<name>pattern). This subpattern will then be indexed in the matches array by its normal numeric position and also by name. PHP 5.2.2 introduced two alternative syntaxes (?<name>pattern) and (?'name'pattern).

Naming subpatterns makes it easier to know what is read from the results of the subpattern : for example, $r['name'] has more meaning than $r[1].

Named subpatterns may also be shifted in the regex without impact on the resulting array.

<?php

$x = 'abc';
preg_match_all('/(?<name>a)/', $x, $r);
print_r($r[1]);
print_r($r['name']);

preg_match("/(?<name>a)(?'sub'b)/", $x, $s);
print $s[2];
print $s['sub'];

?>

See also Subpatterns.

9.351.1. Suggestions

  • Use named regex, and stop using integer-named subpatterns
Short name Structures/NamedRegex
Rulesets Suggestions
Examples Phinx, shopware

9.352. Negative Power

The power operator ** has higher precedence than the sign operators + and -.

This means that -2 ** 2 == -4. It is in fact, -(2 ** 2).

When using negative power, it is clearer to add parenthesis or to use the pow() function, which has no such ambiguity :

<?php

// -2 to the power of 2 (a square)
pow(-2, 2) == 4;

// minus 2 to the power of 2 (a negative square)
-2 ** 2 == -(2 ** 2) == 4;

?>

9.352.1. Suggestions

  • Avoid negative number, as operands of **
  • Use parenthesis with negative numbers and **
Short name Structures/NegativePow
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Instant (5 mins)

9.353. Negative Start Index In Array

Negative starting index in arrays changed in PHP 8.0. Until then, they were ignored, and automatic index started always at 0. Since PHP 8.0, the next index is calculated.

The behavior will break code that relies on automatic index in arrays, when a negative index is used for a starter.

<?php

$x = [-5 => 2];
$x[] = 3;

print_r($x);

/*
PHP 7.4 and older
Array
(
    [-5] => 2
    [0] => 3
)
*/

/*
PHP 8.0 and more recent
Array
(
    [-5] => 2
    [-4] => 3
)
*/

?>

See also PHP RFC: Arrays starting with a negative index.

9.353.1. Suggestions

  • Explicitely create the index, instead of using the automatic indexing
  • Add an explicit index of 0 in the initial array, to set the automatic process in the right track
  • Avoid using specified index in array, conjointly with automatic indexing.
Short name Arrays/NegativeStart
Rulesets CompatibilityPHP80
Severity Minor
Time To Fix Quick (30 mins)

9.354. Nested Ifthen

Three levels of ifthen is too much. The method should be split into smaller functions.

<?php

function foo($a, $b) {
    if ($a == 1) {
        // Second level, possibly too much already
        if ($b == 2) {

        }
    }
}

function bar($a, $b, $c) {
    if ($a == 1) {
        // Second level.
        if ($b == 2) {
            // Third level level.
            if ($c == 3) {
                // Too much
            }
        }
    }
}

?>
Name Default Type Description
nestedIfthen 3 integer Maximal number of acceptable nesting of if-then structures
Short name Structures/NestedIfthen
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)
Examples LiveZilla, MediaWiki

9.355. Nested Ternary

Ternary operators should not be nested too deep.

They are a convenient instruction to apply some condition, and avoid a if() structure. It works best when it is simple, like in a one liner.

However, ternary operators tends to make the syntax very difficult to read when they are nested. It is then recommended to use an if() structure, and make the whole code readable.

<?php

// Simple ternary expression
echo ($a == 1 ? $b : $c) ;

// Nested ternary expressions
echo ($a === 1 ? $d === 2 ? $b : $d : $d === 3 ? $e : $c) ;
echo ($a === 1 ? $d === 2 ? $f ===4 ? $g : $h : $d : $d === 3 ? $e : $i === 5 ? $j : $k) ;

//Previous expressions, written as a if / Then expression
if ($a === 1) {
    if ($d === 2) {
        echo $b;
    } else {
        echo $d;
    }
} else {
    if ($d === 3) {
        echo $e;
    } else {
        echo $c;
    }
}

if ($a === 1) {
    if ($d === 2) {
        if ($f === 4) {
            echo $g;
        } else {
            echo $h;
        }
    } else {
        echo $d;
    }
} else {
    if ($d === 3) {
        echo $e;
    } else {
        if ($i === 5) {
            echo $j;
        } else {
            echo $k;
        }
    }
}

?>

See also Nested Ternaries are Great.

9.355.1. Suggestions

  • Replace ternaries by if/then structures.
  • Replace ternaries by a functioncall : this provides more readability, offset the actual code, and gives room for making it different.
Short name Structures/NestedTernary
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-nested-ternary
Examples SPIP, Zencart

9.356. Nested Ternary Without Parenthesis

It is not allowed to nest ternary operator within itself, without parenthesis. This has been implemented in PHP 7.4.

The reason behind this feature is to keep the code expressive. See the Warning message for more explanations

<?php

$a ? 1 : ($b ? 2 : 3);

// Still valid, as not ambiguous
$a ? $b ? 1 : 2 : 3;

// Produces a warning
//Unparenthesized `a ? b : c ? d : e` is deprecated. Use either `(a ? b : c) ? d : e` or `a ? b : (c ? d : e)`
$a ? 1 : $b ? 2 : 3;

?>

See also PHP RFC: Deprecate left-associative ternary operator.

9.356.1. Suggestions

  • Add parenthesis to nested ternary calls
Short name Php/NestedTernaryWithoutParenthesis
Rulesets CompatibilityPHP74
Php Version 7.4-
Severity Minor
Time To Fix Quick (30 mins)

9.357. Never Used Parameter

When a parameter is never used at calltime, it may be turned into a local variable.

It seems that the parameter was set up initially, but never found its practical usage. It is never mentioned, and always fall back on its default value.

Parameter without a default value are reported by PHP, and are usually always filled.

<?php

// $b may be turned into a local var, it is unused
function foo($a, $b = 1) {
    return $a + $b;
}

// whenever foo is called, the 2nd arg is not mentionned
foo($a);
foo(3);
foo('a');
foo($c);

?>

9.357.1. Suggestions

  • Drop the unused argument in the method definition
  • Actually use the argument when calling the method
  • Drop the default value, and check warnings that mention usage of this parameter
Short name Functions/NeverUsedParameter
Rulesets Analyze, Suggestions
Severity Minor
Time To Fix Slow (1 hour)
Examples Piwigo

9.358. Never Used Properties

Properties that are never used. They are defined in a class or a trait, but they never actually used.

Properties are considered used when they are used locally, in the same class as their definition, or in a parent class : a parent class is always included with the current class.

On the other hand, properties which are defined in a class, but only used in children classes is considered unused, since children may also avoid using it.

<?php

class foo {
    public $usedProperty = 1;

    // Never used anywhere
    public $unusedProperty = 2;

    function bar() {
        // Used internally
        ++$this->usedProperty;
    }
}

class foo2  extends foo {
    function bar2() {
        // Used in child class
        ++$this->usedProperty;
    }
}

// Used externally
++$this->usedProperty;

?>

9.358.1. Suggestions

  • Drop unused properties
  • Change the name of the unused properties
  • Move the properties to children classes
  • Find usage for unused properties
Short name Classes/PropertyNeverUsed
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples WordPress

9.359. New Constants In PHP 7.2

The following constants are now native in PHP 7.2. It is advised to avoid using such names for constant before moving to this new version.

  • PHP_OS_FAMILY
  • PHP_FLOAT_DIG
  • PHP_FLOAT_EPSILON
  • PHP_FLOAT_MAX
  • PHP_FLOAT_MIN
  • SQLITE3_DETERMINISTIC
  • CURLSSLOPT_NO_REVOKE
  • CURLOPT_DEFAULT_PROTOCOL
  • CURLOPT_STREAM_WEIGHT
  • CURLMOPT_PUSHFUNCTION
  • CURL_PUSH_OK
  • CURL_PUSH_DENY
  • CURL_HTTP_VERSION_2TLS
  • CURLOPT_TFTP_NO_OPTIONS
  • CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE
  • CURLOPT_CONNECT_TO
  • CURLOPT_TCP_FASTOPEN
  • DNS_CAA

See also New global constants in 7.2.

Short name Php/Php72NewConstants
Rulesets CompatibilityPHP72
Php Version With PHP 7.2 and older
Severity Major
Time To Fix Slow (1 hour)

9.360. New Constants In PHP 7.4

The following constants are now native in PHP 7.4. It is advised to avoid using such names for constant before moving to this new version.

  • MB_ONIGURUMA_VERSION
  • SO_LABEL
  • SO_PEERLABEL
  • SO_LISTENQLIMIT
  • SO_LISTENQLEN
  • SO_USER_COOKIE
  • PHP_WINDOWS_EVENT_CTRL_C
  • PHP_WINDOWS_EVENT_CTRL_BREAK
  • TIDY_TAG_ARTICLE
  • TIDY_TAG_ASIDE
  • TIDY_TAG_AUDIO
  • TIDY_TAG_BDI
  • TIDY_TAG_CANVAS
  • TIDY_TAG_COMMAND
  • TIDY_TAG_DATALIST
  • TIDY_TAG_DETAILS
  • TIDY_TAG_DIALOG
  • TIDY_TAG_FIGCAPTION
  • TIDY_TAG_FIGURE
  • TIDY_TAG_FOOTER
  • TIDY_TAG_HEADER
  • TIDY_TAG_HGROUP
  • TIDY_TAG_MAIN
  • TIDY_TAG_MARK
  • TIDY_TAG_MENUITEM
  • TIDY_TAG_METER
  • TIDY_TAG_NAV
  • TIDY_TAG_OUTPUT
  • TIDY_TAG_PROGRESS
  • TIDY_TAG_SECTION
  • TIDY_TAG_SOURCE
  • TIDY_TAG_SUMMARY
  • TIDY_TAG_TEMPLATE
  • TIDY_TAG_TIME
  • TIDY_TAG_TRACK
  • TIDY_TAG_VIDEO
  • STREAM_CRYPTO_METHOD_TLSv1_3_CLIENT
  • STREAM_CRYPTO_METHOD_TLSv1_3_SERVER
  • STREAM_CRYPTO_PROTO_TLSv1_3
  • T_COALESCE_EQUAL
  • T_FN

See also New global constants in 7.4.

9.360.1. Suggestions

  • Move the constants to a new namespace
  • Remove the old constants
  • Rename the old constants
Short name Php/Php74NewConstants
Rulesets CompatibilityPHP74
Php Version With PHP 7.4 and older
Severity Major
Time To Fix Slow (1 hour)

9.361. New Functions In PHP 5.4

PHP introduced new functions in PHP 5.4. If there are defined functions with such names, there will be a conflict when upgrading. It is advised to change those functions’ name.

Short name Php/Php54NewFunctions
Rulesets CompatibilityPHP53
Php Version With PHP 5.3 and older
Severity Major
Time To Fix Slow (1 hour)

9.362. New Functions In PHP 5.5

PHP introduced new functions in PHP 5.5. If you have already defined functions with such names, you will get a conflict when trying to upgrade. It is advised to change those functions’ name.

Short name Php/Php55NewFunctions
Rulesets CompatibilityPHP53, CompatibilityPHP54
Php Version With PHP 5.5 and older
Severity Major
Time To Fix Slow (1 hour)

9.363. New Functions In PHP 5.6

PHP introduced new functions in PHP 5.6. If you have already defined functions with such names, you will get a conflict when trying to upgrade. It is advised to change those functions’ name.

Short name Php/Php56NewFunctions
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55
Php Version With PHP 5.6 and older
Severity Major
Time To Fix Slow (1 hour)

9.364. New Functions In PHP 7.0

The following functions are now native functions in PHP 7.0. It is advised to change them before moving to this new version.

Short name Php/Php70NewFunctions
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Slow (1 hour)

9.365. New Functions In PHP 7.1

The following functions are now native functions in PHP 7.1. It is advised to change them before moving to this new version.

Short name Php/Php71NewFunctions
Rulesets CompatibilityPHP71
Php Version With PHP 7.1 and older
Severity Major
Time To Fix Slow (1 hour)

9.366. New Functions In PHP 7.2

The following functions are now native functions in PHP 7.2. It is advised to change custom functions that are currently created, and using those names, before moving to this new version.

9.366.1. Suggestions

  • Move custom functions with the same name to a new namespace
  • Change the name of any custom functions with the same name
  • Add a condition to the functions definition to avoid conflict
Short name Php/Php72NewFunctions
Rulesets CompatibilityPHP72
Php Version With PHP 7.2 and older
Severity Major
Time To Fix Slow (1 hour)

9.367. New Functions In PHP 7.3

New functions are added to new PHP version.

The following functions are now native functions in PHP 7.3. It is compulsory to rename any custom function that was created in older versions. One alternative is to move the function to a custom namespace, and update the use list at the beginning of the script.

Note : At the moment of writing, all links to the manual are not working.

Short name Php/Php73NewFunctions
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56, CompatibilityPHP73
Php Version With PHP 7.3 and older
Severity Major
Time To Fix Quick (30 mins)

9.368. New Functions In PHP 7.4

New functions are added to new PHP version.

The following functions are now native functions in PHP 7.3. It is compulsory to rename any custom function that was created in older versions. One alternative is to move the function to a custom namespace, and update the use list at the beginning of the script.

Note : At the moment of writing, all links to the manual are not working.

Short name Php/Php74NewFunctions
Rulesets CompatibilityPHP74
Php Version With PHP 7.3 and older
Severity Major
Time To Fix Quick (30 mins)

9.369. New Functions In PHP 8.0

New functions are added to new PHP version.

The following functions are now native functions in PHP 7.3. It is compulsory to rename any custom function that was created in older versions. One alternative is to move the function to a custom namespace, and update the use list at the beginning of the script.

Note : At the moment of writing, all links to the manual are not working.

Short name Php/Php80NewFunctions
Rulesets CompatibilityPHP74
Php Version With PHP 8.0 and older
Severity Major
Time To Fix Quick (30 mins)

9.370. Next Month Trap

Avoid using +1 month with strtotime().

strtotime() calculates the next month by incrementing the month number. For day number that do not exist from one month to the next, strtotime() fixes them by setting them in the next-next month.

This happens to January, March, May, July, August and October. January is also vulnerable for 29 (not every year), 30 and 31.

Avoid using ‘+1 month’, and rely on ‘first day of next month’ or ‘last day of next month’ to extract the next month’s name.

<?php

// Base date is October 31 => 10/31
// +1 month adds +1 to 10 => 11/31
// Since November 31rst doesn't exists, it is corrected to 12/01.
echo date('F', strtotime('+1 month',mktime(0,0,0,$i,31,2017))).PHP_EOL;

// Base date is October 31 => 10/31
echo date('F', strtotime('first day of next month',mktime(0,0,0,$i,31,2017))).PHP_EOL;

?>

See also It is the 31st again.

9.370.1. Suggestions

  • Review strtotime() usage for month additions
  • Use datetime() and other classes, not PHP native functions
  • Use a external library, like carbon, to handle dates
Short name Structures/NextMonthTrap
Rulesets Analyze, Top10, CI-checks
Severity Major
Time To Fix Instant (5 mins)
Examples Contao, Edusoho

9.371. No Append On Source

Do not append new elements to an array in a foreach loop. Since PHP 7.0, the array is still used as a source, and will be augmented, and used again.

<?php

// Relying on the initial copy
$a = [1];
$initial = $a;
foreach($initial as $v) {
    $a[] = $v + 1;
}

// Keep new results aside
$a = [1];
$tmp = [];
foreach($a as $v) {
    $tmp[] = $v + 1;
}
$a = array_merge($a, $tmp);
unset($tmp);

// Example, courtesy of Frederic Bouchery
// This is an infinite loop
$a = [1];
foreach($a as $v) {
    $a[] = $v + 1;
}

?>

Thanks to Frederic Bouchery for the reminder.

See also foreach and What will this code return? #PHP.

9.371.1. Suggestions

  • Use a copy of the source, to avoid modifying it during the loop
  • Store the new values in a separate storage
Short name Structures/NoAppendOnSource
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.372. No Boolean As Default

Default values should always be set up with a constant name.

Class constants and constants improve readability when calling the methods or comparing values and statuses.

<?php

const CASE_INSENSITIVE = true;
const CASE_SENSITIVE = false;

function foo($case_insensitive = true) {
    // doSomething()
}

// Readable code
foo(CASE_INSENSITIVE);
foo(CASE_SENSITIVE);


// unreadable code  : is true case insensitive or case sensitive ?
foo(true);
foo(false);

?>

See also FlagArgument and Clean code: The curse of a boolean parameter.

9.372.1. Suggestions

  • Use constants or class constants to give value to a boolean literal
  • When constants have been defined, use them when calling the code
  • Split the method into two methods, one for each case
Short name Functions/NoBooleanAsDefault
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples OpenConf

9.373. No Choice

A conditional structure is being used, but both alternatives are the same, leading to the illusion of choice.

Either the condition is useless, and may be removed, or the alternatives need to be distinguished.

<?php

if ($condition == 2) {
    doSomething();
} else {
    doSomething();
}

$condition == 2 ?     doSomething() :     doSomething();

?>

9.373.1. Suggestions

  • Remove the conditional, and call the expression directly
  • Replace one of the alternative with a distinct call
  • Remove the whole conditional : it may end up being useless
Short name Structures/NoChoice
Rulesets Analyze, Top10, CI-checks
Severity Major
Time To Fix Instant (5 mins)
Examples NextCloud, Zencart

9.374. No Class As Typehint

Avoid using classes as typehint : always use interfaces. This way, different classes, or versions of classes may be passed as argument. The typehint is not linked to an implementation, but to signatures.

A class is needed when the object is with properties : interfaces do not allow the specifications of properties.

<?php

class X {
    public $p = 1;

    function foo() {}
}

interface i {
    function foo();
}

// X is a class : any update in the code requires changing / subclassing X or the rest of the code.
function bar(X $x) {
    $x->foo();
}

// I is an interface : X may implements this interface without refactoring and pass
// later, newer versions of X may get another name, but still implement I, and still pass
function bar2(I $x) {
    $x->foo();
}

function bar3(I $x) {
    echo $x->p;
}

?>

See also Type hinting for interfaces.

9.374.1. Suggestions

  • Create an interface with the important methods, and use that interface
  • Create an abstract class, when public properties are also needed
Short name Functions/NoClassAsTypehint
Rulesets Typechecks
Severity Major
Time To Fix Quick (30 mins)
Examples Vanilla, phpMyAdmin

9.375. No Class In Global

Avoid defining structures in Global namespace. Always prefer using a namespace. This will come handy later, either when publishing the code, or when importing a library, or even if PHP reclaims that name.

<?php

// Code prepared for later
namespace Foo {
    class Bar {}
}

// Code that may conflict with other names.
namespace {
    class Bar {}
}

?>

9.375.1. Suggestions

  • Use a specific namespace for your classes
Short name Php/NoClassInGlobal
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Slow (1 hour)
Examples Dolphin

9.376. No Count With 0

Comparing count(), strlen() or mb_strlen() to 0 is a waste of resources. There are three distinct situations.

When comparing count() with 0, with ===, ==, !==, !=, it is more efficient to use empty(). empty() is a language construct that checks if a value is present, while count() actually load the number of element.

<?php

// Checking if an array is empty
if (count($array) == 0) {
    // doSomething();
}
// This may be replaced with
if (empty($array)) {
    // doSomething();
}

?>

When comparing count() strictly with 0 and >, it is more efficient to use !(empty(  ))

<?php

// Checking if an array is empty
if (count($array) > 0) {
    // doSomething();
}
// This may be replaced with
if (!empty($array)) {
    // doSomething();
}

Of course comparing count() with negative values, or with >= is useless.

<?php

// Checking if an array is empty
if (count($array) < 0) {
    // This never happens
    // doSomething();
}

?>

Comparing count(), strlen() or mb_strlen() with other values than 0 cannot be replaced with a comparison with empty().

Note that this is a micro-optimisation : since PHP keeps track of the number of elements in arrays (or number of chars in strings), the total computing time of both operations is often lower than a ms. However, both functions tends to be heavily used, and may even be used inside loops.

See also count, strlen and mb_strlen.

9.376.1. Suggestions

  • Use empty() on the data
  • Compare the variable with a default value, such as an empty array
Short name Performances/NotCountNull
Rulesets Performances
Severity Minor
Time To Fix Instant (5 mins)
Examples Contao, WordPress

9.377. No Direct Call To Magic Method

PHP features magic methods, which are methods related to operators.

Magic methods, such as __get(), related to =, or __clone(), related to clone, are supposed to be used in an object environment, and not with direct call.

It is recommended to use the magic method with its intended usage, and not to call it directly. For example, typecast to string instead of calling the __toString() method.

<?php
// Write
  print $x->a;
// instead of
  print $x->__get('a');

class Foo {
    private $b = secret;

    public function __toString() {
        return strtoupper($this->b);
    }
}

$bar = new Foo();
echo (string) $bar;

?>

Accessing those methods in a static way is also discouraged.

See also Magic Methods and Magical PHP: `__call <https://www.garfieldtech.com/blog/magical-php-call>`_.

Short name Classes/DirectCallToMagicMethod
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)

9.378. No Direct Usage

The results of the following functions shouldn’t be used directly, but checked first.

For example, glob() returns an array, unless some error happens, in which case it returns a boolean (false). In such case, however rare it is, plugging glob() directly in a foreach() loops will yield errors.

<?php
    // Used without check :
    foreach(glob('.') as $file) { /* do Something */ }.

    // Used without check :
    $files = glob('.');
    if (!is_array($files)) {
        foreach($files as $file) { /* do Something */ }.
    }
?>

9.378.1. Suggestions

  • Check the return of the function before using it, in particular for false, or array().
Short name Structures/NoDirectUsage
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)
Examples Edusoho, XOOPS

9.379. No ENT_IGNORE

Certain characters have special significance in HTML, and should be represented by HTML entities if they are to preserve their meanings.

ENT_IGNORE is a configuration option for htmlspecialchars(), that ignore any needed character replacement. This mean the raw input will now be processed by PHP, or a target browser.

It is recommended to use the other configuration options : ENT_COMPAT, ENT_QUOTES, ENT_NOQUOTES, ENT_SUBSTITUTE, ENT_DISALLOWED, ENT_HTML401, ENT_XML1, ENT_XHTML or ENT_HTML5.

<?php

// This produces a valid HTML tag
$new = htmlspecialchars("<a href='test'>Test</a>", ENT_IGNORE);
echo $new; // &lt;a href=&#039;test&#039;&gt;Test&lt;/a&gt;

// This produces a valid string, without any HTML special value
$new = htmlspecialchars("<a href='test'>Test</a>", ENT_QUOTES);
echo $new; // &lt;a href=&#039;test&#039;&gt;Test&lt;/a&gt;

?>

See also htmlspecialchars and Deletion of Code Points.

9.379.1. Suggestions

  • Use of the the other options
Short name Security/NoEntIgnore
Rulesets Security
Severity Minor
Time To Fix Quick (30 mins)

9.380. No Empty Regex

PHP regex don’t accept empty regex, nor regex with alphanumeric delimiter.

Most of those errors happen at execution time, when the regex is build dynamically, but still may end empty. At compile time, such error are made when the code is not tested before commit.

<?php

// No empty regex
preg_match('', $string, $r);

// Delimiter must be non-alphanumerical
preg_replace('1abc1', $string, $r);

// Delimiter must be non-alphanumerical
preg_replace('1'.$regex.'1', $string, $r);

?>

See also PCRE and Delimiters.

9.380.1. Suggestions

  • Fix the regex by adding regex delimiters
Short name Structures/NoEmptyRegex
Rulesets Analyze, CI-checks
Severity Critical
Time To Fix Quick (30 mins)
Examples Tikiwiki

9.381. No Hardcoded Hash

Hash should never be hardcoded.

Hashes may be MD5, SHA1, SHA512, Bcrypt or any other. Such values must be easily changed, for security reasons, and the source code is not the safest place to hide it.

<?php

    // Those strings may be sha512 hashes.
    // it is recomemdned to check if they are static or should be put into configuration
    $init512 = array( // initial values for SHA512
        '6a09e667f3bcc908', 'bb67ae8584caa73b', '3c6ef372fe94f82b', 'a54ff53a5f1d36f1',
    );

    // strings which are obvious conversion are ignored
    $decimal = intval('87878877', 12);
?>

See also Salted Password Hashing - Doing it Right and Hash-Buster.

9.381.1. Suggestions

  • Put any hardcoded hash in a configuration file, a database or a environment variable. An external source.
Short name Structures/NoHardcodedHash
Rulesets Analyze, Security
Severity Critical
Time To Fix Slow (1 hour)
Examples shopware, SugarCrm

9.382. No Hardcoded Ip

Do not leave hard coded IP in your code.

It is recommended to move such configuration in external files or databases, for each update. This may also come handy when testing.

<?php

// This IPv4 is hardcoded.
$ip = '183.207.224.50';
// This IPv6 is hardcoded.
$ip = '2001:0db8:85a3:0000:0000:8a2e:0370:7334';

// This looks like an IP
$thisIsNotAnIP = '213.187.99.50';
$thisIsNotAnIP = '2133:1387:9393:5330';

?>

127.0.0.1, \:\:1 and \:\:0 are omitted, and not considered as a violation.

See also Use of Hardcoded IPv4 Addresses and Never hard code sensitive information.

9.382.1. Suggestions

  • Move the hardcoded IP to an external source : environment variable, configuration file, database.
  • Remove the hardcoded IP and ask for it at execution.
  • Use a literal value for default messages in form.
Short name Structures/NoHardcodedIp
Rulesets Analyze, Security
Severity Minor
Time To Fix Slow (1 hour)
Examples OpenEMR, NextCloud

9.383. No Hardcoded Path

It is not recommended to use hardcoded literals when designating files. Full paths are usually tied to one file system organization. As soon as the organisation changes or must be adapted to any external constraint, the path is not valid anymore.

Either use __FILE__ and __DIR__ to make the path relative to the current file; use a DOC_ROOT as a configuration constant that will allow the moving of the script to another folder; finally functions like sys_get_temp_dir() produce a viable temporary folder.

Relative paths are relative to the current execution directory, and not the current file. This means they may differ depending on the location of the start of the application, and are sensitive to chdir() and chroot() usage.

<?php

    // This depends on the current executed script
    file_get_contents('token.txt');

    // Exotic protocols are ignored
    file_get_contents('jackalope://file.txt');

    // Some protocols are ignored : http, https, ftp, ssh2, php (with memory)
    file_get_contents('http://www.php.net/');
    file_get_contents('php://memory/');

    // glob() with special chars * and ? are not reported
    glob('./*/foo/bar?.txt');
    // glob() without special chars * and ? are reported
    glob('/foo/bar/');

?>

9.383.1. Suggestions

  • Add __DIR__ before the path to make it relative to the current file
  • Add a configured prefix before the path to point to any file in the system
  • Use sys_get_temp_dir() for temporary data
  • Use include_path argument function, such as fie_get_contents(), to have the file located in configurable directories.
Short name Structures/NoHardcodedPath
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)
ClearPHP no-hardcoded-path
Examples Tine20, Thelia

9.384. No Hardcoded Port

When connecting to a remove server, port is an important information. It is recommended to make this configurable (with constant or configuration), to as to be able to change this value without changing the code.

<?php

    // Both configurable IP and hostname
    $connection = ssh2_connect($_ENV['SSH_HOST'], $_ENV['SSH_PORT'], $methods, $callbacks);

    // Both hardcoded IP and hostname
    $connection = ssh2_connect('shell.example.com', 22, $methods, $callbacks);

    if (!$connection) die('Connection failed');
?>

9.384.1. Suggestions

  • Move the port to a configuration file, an environment variable
Short name Structures/NoHardcodedPort
Rulesets Analyze, Security
Severity Minor
Time To Fix Quick (30 mins)
Examples WordPress

9.385. No List With String

list() can’t be used anymore to access particular offset in a string. This should be done with substr() or $string[$offset] syntax.

<?php

$x = 'abc';
list($a, $b, $c) = $x;

//list($a, $b, $c) = 'abc'; Never works

print $c;
// PHP 5.6- displays 'c'
// PHP 7.0+ displays nothing

?>

See also PHP 7.0 Backward incompatible changes : list() can no longer unpack string variables .

9.385.1. Suggestions

  • Use str_split() to break a string into bytes
  • Use substr() or $string[$offset] syntax to access specific bytes in the string
Short name Php/NoListWithString
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Instant (5 mins)

9.386. No Literal For Reference

Method arguments and return values may be by reference. Then, they need to be a valid variable.

Objects are always passed by reference, so there is no need to explicitly declare it.

Expressions, including ternary operator, produce value, and can’t be used by reference directly. This is also the case for expression that include one or more reference.

<?php

// variables, properties, static properties, array items are all possible
$a = 1;
foo($a);

//This is not possible, as a literal can't be a reference
foo(1);

function foo(&$int) { return $int; }


// This is not a valid reference
function &bar() { return 2; }
function &bar2() { return 2 + $r; }

?>

Wrongly passing a value as a reference leads to a PHP Notice.

See also References.

9.386.1. Suggestions

  • Remove the reference in the method signature (argument or return value)
  • Make the argument an object, by using a typehint (non-scalar)
  • Put the value into a variable prior to call (or return) the method
Short name Functions/NoLiteralForReference
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.387. No Magic With Array

Magic method __set() doesn’t work for array syntax.

When overloading properties, they can only be used for scalar values, excluding arrays. Under the hood, PHP uses __get() to reach for the name of the property, and doesn’t recognize the following index as an array. It yields an error : Indirect modification of overloaded property.

<?php

class c {
    private $a;
    private $o = array();

    function __get($name) {
        return $this->o[$name];
    }

    function foo() {
        // property b doesn't exists
        $this->b['a'] = 3;

        print_r($this);
    }

    // This method has no impact on the issue
    function __set($name, $value) {
        $this->o[$name] = $value;
    }
}

$c = new c();
$c->foo();

?>

It is possible to use the array syntax with a magic property : by making the __get returns an array, the syntax will actually extract the expected item in the array.

This is not reported by linting.

In this analysis, only properties that are found to be magic are reported. For example, using the b property outside the class scope is not reported, as it would yield too many false-positives.

See also Overload.

9.387.1. Suggestions

  • Use a distinct method to append a new value to that property
  • Assign the whole array, and not just one of its elements
Short name Classes/NoMagicWithArray
Rulesets Analyze, LintButWontExec, CI-checks
Severity Major
Time To Fix Slow (1 hour)

9.388. No More Curly Arrays

Only use square brackets to access array elements. The usage of curly brackets for array access is deprecated since PHP 7.4.

<?php

$array = [1,2,3];

// always valid
echo $array[1];

// deprecated in PHP 7.4
echo $array{1};

?>

See also Deprecate curly brace syntax and Deprecate curly brace syntax for accessing array elements and string offsets.

9.388.1. Suggestions

  • Always use square brackets to access particular index in an array
Short name Php/NoMoreCurlyArrays
Rulesets CompatibilityPHP74
Php Version 8.0-
Severity Minor
Time To Fix Quick (30 mins)
Precision Very high

9.389. No Need For Else

Else is not needed when the Then ends with a break. A break may be the following keywords : break, continue, return, goto. Any of these send the execution somewhere in the code. The else block is then executed as the main sequence, only if the condition fails.

<?php

function foo() {
    // Else may be in the main sequence.
    if ($a1) {
        return $a1;
    } else {
        $a++;
    }

    // Same as above, but negate the condition : if (!$a2) { return $a2; }
    if ($a2) {
        $a++;
    } else {
        return $a2;
    }

    // This is OK
    if ($a3) {
        return;
    }

    // This has no break
    if ($a4) {
        $a++;
    } else {
        $b++;
    }

    // This has no else
    if ($a5) {
        $a++;
    }
}
?>

See also Object Calisthenics, rule # 2.

9.389.1. Suggestions

  • Remove else block, but keep the code
Short name Structures/NoNeedForElse
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples Thelia, ThinkPHP

9.390. No Need For Triple Equal

There is no need for the identity comparison when the methods returns the proper type.

<?php

// foo() returns a string.
if ('a' === foo()) {
    // doSomething()
}


function foo() : string {
    return 'a';
}

?>

9.390.1. Suggestions

Short name Structures/NoNeedForTriple
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.391. No Need For get_class()

There is no need to call get_class() to build a static call. The argument of get_class() may be used directly.

<?php

//
$a->b::$c

// This is too much code
get_class($a->b)::$c

?>

See also Scope Resolution Operator (::).

9.391.1. Suggestions

  • Use get_called_class(), which may carry different class names
  • Use self, static or parent keywords, if you are already in the current class
  • Use the argument of get_class() directly
Short name Structures/NoNeedGetClass
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.392. No Net For Xml Load

Simplexml and ext/DOM load all external entities from the web, by default. This is dangerous, in particular when loading unknown XML code.

Look at this XML code below : it is valid. It defines an entity xxe, that is filled with a file, read on the system and base64 encoded.:

&lt;!DOCTYPE replace [&lt;!ENTITY xxe SYSTEM "php://filter/convert.base64-encode/resource=index.php"&gt; ]&gt;
<replace>&xxe;</replace>

This file could be processed with the following code : note, you can replace ‘index.php’ in the above entity by any valid filepath.

<?php
    $dom = new DOMDocument();
    $dom->loadXML($xml, LIBXML_NOENT | LIBXML_DTDLOAD);
    $info = simplexml_import_dom($dom);

    print base64_decode($info[0]);
?>

Here, PHP tries to load the XML file, finds the entity, then solves the entity by encoding a file called index.php. The source code of the file is not used as data in the XML file.

At that point, the example illustrates how a XXE works : by using the XML engine to load external resources, and preprocessing the XML code. in fact, there is only one change to make this XML code arbitrarily injected ::

&lt;!DOCTYPE replace [&lt;!ENTITY writer SYSTEM https://www.example.com/entities.dtd&gt; ]&gt;
<replace>&xxe;</replace>

With the above example, the XML code is static (as, it never changes), but the ‘xxe’ definitions are loaded from a remove website, and are completely under the attacker control.

See also XML External Entity, XML External Entity (XXE) Processing and Detecting and exploiting XXE in SAML Interfaces.

9.392.1. Suggestions

  • Strip out any entity when using external XML
  • Forbid any network to the XML engine, by configuring the XML engine without network access
Short name Security/NoNetForXmlLoad
Rulesets Security
Severity Major
Time To Fix Slow (1 hour)

9.393. No Parenthesis For Language Construct

Some PHP language constructs, such are include, print, echo don’t need parenthesis. They accept parenthesis, but it is may lead to strange situations.

<?php

// This is an attempt to load 'foo.inc', or kill the script
include('foo.inc') or die();
// in fact, this is read by PHP as : include 1
// include  'foo.inc' or die();

?>

It it better to avoid using parenthesis with echo, print, return, throw, yield, yield from, include, require, include_once, require_once.

See also include.

9.393.1. Suggestions

  • Remove parenthesis
Short name Structures/NoParenthesisForLanguageConstruct
Rulesets Analyze, Suggestions, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
ClearPHP no-parenthesis-for-language-construct
Examples Phpdocumentor, phpMyAdmin

9.394. No Plus One

Incrementing a variable should be done with the ++ or – operators. Any other way, may be avoided.

<?php

// Best way to increment
++$x; --$y;

// Second best way to increment, if the current value is needed :
echo $x++, $y--;

// Good but slow
$x += 1;
$x -= -1;

$y += -1;
$y -= 1;

// even slower
$x = $x + 1;
$y = $y - 1;

?>
Short name Structures/PlusEgalOne
Rulesets Coding Conventions
Severity Minor
Time To Fix Quick (30 mins)

9.395. No Public Access

The properties below are declared with public access, but are never used publicly. They can be made protected or private.

<?php

class foo {
    public $bar = 1;            // Public, and used in public space
    public $neverInPublic = 3;  // Public, but never used in outside the class

    function bar() {
        $neverInPublic++;
    }
}

$x = new foo();
$x->bar = 3;
$x->bar();

?>
Short name Classes/NoPublicAccess
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.396. No Real Comparison

Avoid comparing decimal numbers with ==, ===, !==, !=. Real numbers have an error margin which is random, and makes it very difficult to match even if the compared value is a literal.

PHP uses an internal representation in base 2 : any number difficult to represent with this base (like 0.1 or 0.7) will have a margin of error.

<?php

$a = 1/7;
$b = 2.0;

// 7 * $a is a real, not an integer
var_dump( 7 * $a === 1);

// rounding error leads to wrong comparison
var_dump( (0.1 + 0.7) * 10 == 8);
// although
var_dump( (0.1 + 0.7) * 10);
// displays 8

// precision formula to use with reals. Adapt 0.0001 to your precision needs
var_dump( abs(((0.1 + 0.7) * 10) - 8) < 0.0001);

?>

Use precision formulas with abs() to approximate values with a given precision, or avoid reals altogether.

See also Floating point numbers.

9.396.1. Suggestions

  • Cast the values to integer before comparing
  • Compute the difference, and keep it below a threshold
  • Use the gmp or the bc extension to handle high precision numbers
  • Change the ‘precision’ directive of PHP : ini_set(‘precision’, 30) to make number larger
  • Multiply by a power of ten, before casting to integer for the comparison
  • Use floor(), ceil() or round() to compare the numbers, with a specific precision
Short name Type/NoRealComparison
Rulesets Analyze, Top10, CI-checks
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-real-comparison
Examples Magento, SPIP

9.397. No Reference For Static Property

Static properties used to behave independently when set to a reference value. This was fixed in PHP 7.3.

According to the PHP 7.3 changelog : In PHP, `static <https://www.php.net/manual/en/language.oop5.static.php>`_ properties are shared between inheriting classes, unless the `static <https://www.php.net/manual/en/language.oop5.static.php>`_ property is explicitly overridden in a child class. However, due to an implementation artifact it was possible to separate the `static <https://www.php.net/manual/en/language.oop5.static.php>`_ properties by assigning a reference. This loophole has been fixed..

<?php

        class Test {
            public static $x = 0;
        }
        class Test2 extends Test { }

        Test2::$x = &$x;
        $x = 1;

        var_dump(Test::$x, Test2::$x);
        // Previously: int(0), int(1)
        // Now: int(1), int(1)

?>

See also PHP 7.3 UPGRADE NOTES.

Short name Php/NoReferenceForStaticProperty
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.3 and older
Severity Major
Time To Fix Slow (1 hour)

9.398. No Reference For Ternary

The ternary operator and the null coalescing operator are both expressions that only return values, and not a variable.

This means that any provided reference will be turned into its value. While this is usually invisible, it will raise a warning when a reference is expected. This is the case with methods returning a reference.

A PHP notice is generated when using a ternary operator or the null coalesce operator : Only variable references should be returned by reference. The notice is also emitted when returning objects.

This applies to methods, functions and closures.

<?php

// This works
function &foo($a, $b) {
    if ($a === 1) {
        return $b;
    } else {
        return $a;
    }
}

// This raises a warning, as the operator returns a value
function &foo($a, $b) { return $a === 1 ? $b : $a; }

?>

See also Null Coalescing Operator, Ternary Operator.

9.398.1. Suggestions

  • Drop the reference at assignation time
  • Drop the reference in the argument definition
  • Drop the reference in the function return definition
Short name Php/NoReferenceForTernary
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Slow (1 hour)
Examples phpadsnew

9.399. No Reference On Left Side

Do not use references as the right element in an assignation.

<?php

$b = 2;
$c = 3;

$a = &$b + $c;
// $a === 2 === $b;

$a = $b + $c;
// $a === 5

?>

This is the case for most situations : addition, multiplication, bitshift, logical, power, concatenation. Note that PHP won’t compile the code if the operator is a short operator (+=, .=, etc.), nor if the & is on the right side of the operator.

Short name Structures/NoReferenceOnLeft
Rulesets Analyze, CI-checks
Severity Critical
Time To Fix Quick (30 mins)

9.400. No Return For Generator

Return is not allowed in generator. In PHP versions older than 5.6 and older, they yield a fatal Error.

<?php

function generatorWithReturn() {
    yield 1;
    return 2;
}

?>

See also Generators overview.

Short name Php/NoReturnForGenerator
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and more recent
Severity Critical
Time To Fix Quick (30 mins)

9.401. No Return Or Throw In Finally

Avoid using return and throw in a finally block. Both command will interrupt the processing of the try catch block, and any exception that was emitted will not be processed. This leads to unprocessed exceptions, leaving the application in an unstable state.

Note that PHP prevents the usage of goto, break and continue within the finally block at linting phase. This is categorized as a Security problem.

<?php
function foo() {
        try {
            // Exception is thrown here
            throw new \Exception();
        } catch (Exception $e) {
            // This is executed AFTER finally
            return 'Exception';
        } finally {
            // This is executed BEFORE catch
            return 'Finally';
        }
    }
}

// Displays 'Finally'. No exception
echo foo();

function bar() {
        try {
            // Exception is thrown here
            throw new \Exception();
        } catch (Exception $e) {
            // Process the exception.
            return 'Exception';
        } finally {
            // clean the current situation
            // Keep running the current function
        }
        return 'Finally';
    }
}

// Displays 'Exception', with processed Exception
echo bar();

?>

See also Return Inside Finally Block.

9.401.1. Suggestions

  • Move the return right after the try/catch/finally call
Short name Structures/NoReturnInFinally
Rulesets Security
Severity Major
Time To Fix Quick (30 mins)

9.402. No Return Used

The return value of the following functions are never used. The return argument may be dropped from the code, as it is dead code.

This analysis supports functions and static methods, when a definition may be found. It doesn’t support method calls.

<?php

function foo($a = 1;) { return 1; }
foo();
foo();
foo();
foo();
foo();
foo();

// This function doesn't return anything.
function foo2() { }

// The following function are used in an expression, thus the return is important
function foo3() {  return 1;}
function foo4() {  return 1;}
function foo5() {  return 1;}

foo3() + 1;
$a = foo4();
foo(foo5());

?>

9.402.1. Suggestions

  • Remove the return statement in the function
  • Actually use the value returned by the method, for test or combination with other values
Short name Functions/NoReturnUsed
Rulesets Analyze, Suggestions
Severity Minor
Time To Fix Slow (1 hour)
Examples SPIP, LiveZilla

9.403. No Self Referencing Constant

It is not possible to use a constant to define itself in a class. It yields a fatal error at runtime.

The PHP error reads : Cannot declare `self <https://www.php.net/manual/en/language.oop5.paamayim-nekudotayim.php>`_-referencing constant '`self <https://www.php.net/manual/en/language.oop5.paamayim-nekudotayim.php>`_\:\:C2'. Unlike PHP which is self-referencing, self referencing variables can’t have a value : just don’t use that.

<?php
    class a {
        const C1 = 1;         // fully defined constant
        const C2 = self::C2;  // self referencing constant
        const C3 = a::C3 + 2; // self referencing constant
    }
?>

The code may access an already declared constant with self or with its class name.

<?php
    class a {
        const C1 = 1;
        const C2 = a::C1;
    }
?>

This error is not detected by linting. It is only detected at instantiation time : if the class is not used, it won’t appear.

9.403.1. Suggestions

  • Give a literal value to this constant
  • Give a constant value to this constant : other class constants or constant are allowed here.
Short name Classes/NoSelfReferencingConstant
Rulesets Analyze, LintButWontExec, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.404. No Spread For Hash

The spread operator ... only works on integer-indexed arrays.

<?php

// This is valid, as ``-33`` is cast to integer by PHP automagically
var_dump(...[1,-33 => 2, 3]);

// This is not valid
var_dump(...[1,C => 2, 3]);

?>

See also Variable-length argument lists.

9.404.1. Suggestions

  • Add a call to array_values() instead of the hash
Short name Arrays/NoSpreadForHash
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.405. No String With Append

PHP 7 doesn’t allow the usage of [] with strings. [] is an array-only operator.

<?php

$string = 'abc';

// Not possible in PHP 7
$string[] = 'd';

?>

This was possible in PHP 5, but is now forbidden in PHP 7.

9.405.1. Suggestions

  • Use the concatenation operator . to append strings.
  • Use the concatenation short assignement .= to append strings.
Short name Php/NoStringWithAppend
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and more recent
Severity Major
Time To Fix Quick (30 mins)

9.406. No Substr Minus One

Negative index were introduced in PHP 7.1. This syntax is not compatible with PHP 7.0 and older.

<?php
$string = 'abc';

echo $string[-1]; // c

echo $string[1]; // a

?>

See also Generalize support of negative string offsets.

9.406.1. Suggestions

  • Use the -1 index in a string, instead of a call to substr()
Short name Php/NoSubstrMinusOne
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.1 and more recent
Severity Major
Time To Fix Quick (30 mins)

9.407. No Weak SSL Crypto

When enabling PHP’s stream SSL, it is important to use a safe protocol.

All the SSL protocols (1.0, 2.0, 3.0), and TLS (1.0 are unsafe. The best is to use the most recent TLS, version 1.2.

stream_socket_enable_crypto() and curl_setopt() are checked.

<?php

// This socket will use SSL v2, which
$socket = 'sslv2://www.example.com';
$fp = fsockopen($socket, 80, $errno, $errstr, 30);

?>

Using the TLS transport protocol of PHP will choose the version by itself.

See also Insecure Transportation Security Protocol Supported (TLS 1.0), The 2018 Guide to Building Secure PHP Software and Internet Domain: TCP, UDP, SSL, and TLS.

9.407.1. Suggestions

  • Use TLS transport, with version 1.2
Short name Security/NoWeakSSLCrypto
Rulesets Security
Severity Minor
Time To Fix Quick (30 mins)

9.408. No array_merge() In Loops

array_merge() is memory intensive : every call will duplicate the arguments in memory, before merging them.

To handle arrays that may be quite big, it is recommended to avoid using array_merge() in a loop. Instead, one should use array_merge() with as many arguments as possible, making the merge a on time call.

<?php

// A large multidimensional array
$source = ['a' => ['a', 'b', /*...*/],
           'b' => ['b', 'c', 'd', /*...*/],
           /*...*/
           ];

// Faster way
$b = array();
foreach($source as $key => $values) {
    //Collect in an array
    $b[] = $values;
}

// One call to array_merge
$b = call_user_func_array('array_merge', $b);
// or with variadic
$b = call_user_func('array_merge', ..$b);

// Fastest way (with above example, without checking nor data pulling)
$b = call_user_func_array('array_merge', array_values($source))
// or
$b = call_user_func('array_merge', ...array_values($source))

// Slow way to merge it all
$b = array();
foreach($source as $key => $values) {
    $b = array_merge($b, $values);
}

?>

Note that array_merge_recursive() and file_put_contents() are affected and reported the same way.

9.408.1. Suggestions

  • Store all intermediate arrays in a temporary variable, and use array_merge() once, with ellipsis or call_user_func_array().
Short name Performances/ArrayMergeInLoops
Rulesets Analyze, Performances, Top10, CI-checks
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-array_merge-in-loop
Examples Tine20

9.409. No get_class() With Null

It is not possible to pass explicitly null to get_class() to get the current’s class name. Since PHP 7.2, one must call get_class() without arguments to achieve that result.

<?php

class A {
  public function f() {
    // Gets the classname
    $classname = get_class();

    // Gets the classname and a warning
    $classname = get_class(null);
  }
}

$a = new A();
$a->f('get_class');

?>
Short name Structures/NoGetClassNull
Rulesets Analyze, CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56, CompatibilityPHP72
Severity Major
Time To Fix Instant (5 mins)

9.410. No isset() With empty()

empty() actually does the job of isset() too.

From the manual : No warning is generated if the variable does not exist. That means `empty() <https://www.php.net/empty>`_ is essentially the concise equivalent to !`isset( <https://www.www.php.net/isset>`_$var) || $var == false. The main difference is that isset() only works with variables, while empty() works with other structures, such as constants.

<?php


// Enough validation
if (!empty($a)) {
    doSomething();
}

// Too many tests
if (isset($a) && !empty($a)) {
    doSomething();
}

?>

See also Isset <http://www.php.net/`isset>`_ and empty.

9.410.1. Suggestions

  • Only use isset(), just drop the empty()
  • Only use empty(), just drop the empty()
  • Use a null value, so the variable is always set
Short name Structures/NoIssetWithEmpty
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples XOOPS

9.411. No mb_substr In Loop

Do not use loops on mb_substr().

mb_substr() always starts at the beginning of the string ot search for the nth char, and recalculate everything. This means that the first iterations are as fast as substr() (for comparison), while the longer the string, the slower mb_substr().

The recommendation is to use preg_split() with the u option, to split the string into an array. This save multiple recalculations.

<?php

// Split the string by characters
$array = preg_split('//u', $string, -1, PREG_SPLIT_NO_EMPTY);
foreach($array as $c) {
    doSomething($c);
}

// Slow version
$nb = mb_strlen($mb);
for($i = 0; $i < $nb; ++$i) {
    // Fetch a character
    $c = mb_substr($string, $i, 1);
    doSomething($c);
}

?>

See also Optimization: How I made my PHP code run 100 times faster and How to iterate UTF-8 string in PHP?.

9.411.1. Suggestions

  • Use preg_split() and loop on its results.
Short name Performances/MbStringInLoop
Rulesets Performances
Severity Minor
Time To Fix Quick (30 mins)

9.412. Non Ascii Variables

PHP allows certain characters in variable names. The variable name must only include letters, figures, underscores and ASCII characters from 128 to 255.

In practice, letters outside the scope of a-zA-Z0-9 are rare, and require more care when editing the code or passing it from OS to OS.

<?php

class  {
    // An actual working class in PHP.
    public function __construct() {
        echo __CLASS__;
    }
}

$人民 = new ();

?>

See also Variables.

9.412.1. Suggestions

  • Make sure those special chars have actual meaning.
Short name Variables/VariableNonascii
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples Magento

9.413. Non Nullable Getters

A getter needs to be nullable when a property is injected.

In particular, if the injection happens with a separate method, there is a time where the object is not consistent, and the property holds a default non-object value.

<?php

class Consistent {
    private $db = null;

    function __construct(Db $db) {
        $this->db = $db;
        // Object is immediately consistent
    }

    // Db might be null
    function getDb() {
        return $this->db;
    }
}

class Inconsistent {
    private $db = null;

    function __construct() {
        // No initialisation
    }

    // This might be called on time, or not
    // This typehint cannot be nullable, nor use null as default
    function setDb(DB $db) {
        return $this->db;
    }

    // Db might be null
    function getDb() {
        return $this->db;
    }
}
?>

9.413.1. Suggestions

  • Remove the nullable option and the tests on null.
Short name Classes/NonNullableSetters
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.414. Non Static Methods Called In A Static

Static methods have to be declared as such (using the static keyword). Then, one may call them without instantiating the object.

PHP 7.0, and more recent versions, yield a deprecated error : Non-`static <https://www.php.net/manual/en/language.oop5.static.php>`_ method A\:\:B() should not be called statically.

PHP 5 and older doesn’t check that a method is static or not : at any point, the code may call one method statically.

<?php
    class x {
        static public function sm( ) { echo __METHOD__.\n; }
        public public sm( ) { echo __METHOD__.\n; }
    }

    x::sm( ); // echo x::sm

    // Dynamic call
    ['x', 'sm']();
    [\x::class, 'sm']();

    $s = 'x::sm';
    $s();

?>

It is a bad idea to call non-static method statically. Such method may make use of special variable $this, which will be undefined. PHP will not check those calls at compile time, nor at running time.

It is recommended to update this situation : make the method actually static, or use it only in object context.

Note that this analysis reports all static method call made on a non-static method, even within the same class or class hierarchy. PHP silently accepts static call to any in-family method.

<?php
    class x {
        public function foo( ) { self::bar() }
        public function bar( ) { echo __METHOD__.\n; }
    }
?>

See also Static Keyword <https://www.php.net/manual/en/language.oop5.`static.php>`_.

9.414.1. Suggestions

  • Call the method the correct way
  • Define the method as static
Short name Classes/NonStaticMethodsCalledStatic
Rulesets Analyze, CompatibilityPHP56, CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples Dolphin, Magento

9.415. Non-constant Index In Array

Undefined constants revert as strings in Arrays. They are also called barewords.

In $array[index], PHP cannot find index as a constant, but, as a default behavior, turns it into the string index.

This default behavior raise concerns when a corresponding constant is defined, either using define() or the const keyword (outside a class). The definition of the index constant will modify the behavior of the index, as it will now use the constant definition, and not the ‘index’ string.

<?php

// assign 1 to the element index in $array
// index will fallback to string
$array[index] = 1;
//PHP Notice:  Use of undefined constant index - assumed 'index'

echo $array[index];      // display 1 and the above error
echo "$array[index]";    // display 1
echo "$array['index']";  // Syntax error


define('index', 2);

 // now 1 to the element 2 in $array
 $array[index] = 1;

?>

It is recommended to make index a real string (with ‘ or “), or to define the corresponding constant to avoid any future surprise.

Note that PHP 7.2 removes the support for this feature.

See also PHP RFC: Deprecate and Remove Bareword (Unquoted) Strings and Syntax.

9.415.1. Suggestions

  • Declare the constant to give it an actual value
  • Turn the constant name into a string
Short name Arrays/NonConstantArray
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)
Examples Dolibarr, Zencart

9.416. Non-lowercase Keywords

The usual convention is to write PHP keywords (like as, foreach, switch, case, break, etc.) all in lowercase.

<?php

// usual PHP convention
foreach($array as $element) {
    echo $element;
}

// unusual PHP conventions
Foreach($array AS $element) {
    eCHo $element;
}

?>

PHP understands them in lowercase, UPPERCASE or WilD Case, so there is nothing compulsory here. Although, it will look strange to many.

Some keywords are missing from this analysis : extends, implements, as. This is due to the internal engine, which doesn’t keep track of them in its AST representation.

9.416.1. Suggestions

  • Use lowercase only PHP keywords, except for constants such as __CLASS__.
Short name Php/UpperCaseKeyword
Rulesets Coding Conventions
Severity Minor
Time To Fix Instant (5 mins)

9.417. Not A Scalar Type

int is the actual PHP scalar type, not integer.

PHP 7 introduced several scalar types, in particular int, bool and float. Those three types are easily mistaken with integer, boolean, real and double.

Unless those classes actually exists, PHP emits some strange error messages.

<?php

// This expects a scalar of type 'integer'
function foo(int $i) {}

// This expects a object of class 'integer'
function abr(integer $i) {}

?>

Thanks to Benoit Viguier for the original idea for this analysis.

See also Type declarations.

9.417.1. Suggestions

  • Do not use int as a class name, an interface name or a trait name.
Short name Php/NotScalarType
Rulesets Typechecks
Severity Major
Time To Fix Instant (5 mins)

9.418. Not Equal Is Not !==

Not and Equal operators, used separately, don’t amount to the different operator !==.

!$a == $b first turns $a``into the opposite boolean, then compares this boolean value to ``$b. On the other hand, $a !== $b compares the two variables for type and value, and returns a boolean.

<?php

if ($string != 'abc') {
    // doSomething()
}

// Here, string will be an boolean, leading
if (!$string == 'abc') {
    // doSomething()
}

// operator priority may be confusing
if (!$object instanceof OneClass) {
    // doSomething()
}
?>

Note that the instanceof operator may be use with this syntax, due to operator precedence.

See also Operator Precedence.

9.418.1. Suggestions

  • Use the != or !==
  • Use parenthesis
Short name Structures/NotEqual
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.419. Not Not

Double not makes a boolean, not a true.

This is a wrong casting to boolean. PHP supports (boolean) to do the same, faster and cleaner.

<?php
    // Explicit code
    $b = (boolean) $x;
    $b = (bool) $x;

    // Wrong type casting
    $b = !!$x;

?>

See also Logical Operators and Type Juggling.

9.419.1. Suggestions

  • Use (bool) casting operator for that
  • Don’t typecast, and let PHP handle it. This works in situations where the boolean is immediately used.
Short name Structures/NotNot
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP no-implied-cast
Examples Cleverstyle, Tine20

9.420. Null On New

Until PHP 7, some classes instantiation could yield null, instead of throwing an exception.

After issuing a ‘new’ with those classes, it was important to check if the returned object were null or not. No exception were thrown.

<?php

// Example extracted from the wiki below
$mf = new MessageFormatter('en_US', '{this was made intentionally incorrect}');
if ($mf === null) {
    echo 'Surprise!';
}

?>

This inconsistency has been cleaned in PHP 7 : see See Internal Constructor Behavior

See also PHP RFC: Constructor behaviour of internal classes.

9.420.1. Suggestions

  • Remove the check on null after a new instantiation
Short name Classes/NullOnNew
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Instant (5 mins)

9.421. Null Or Boolean Arrays

Null and booleans are valid PHP array base. Yet, they only produces null values. They also did not emits any warning until PHP 7.4.

This analysis has been upgraded to cover int and float types too.

<?php

// outputs NULL
var_dump(null[0]);

const MY_CONSTANT = true;
// outputs NULL
var_dump(MY_CONSTANT[10]);

?>

See also Null and True.

9.421.1. Suggestions

  • Avoid using the array syntax on null and boolean
  • Avoid using null and boolean on constant that are expecting arrays
Short name Arrays/NullBoolean
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.422. Nullable With Constant

Arguments are automatically nullable with a literal null. They used to also be nullable with a constant null, before PHP 8.0.

<?php

// Extracted from https://github.com/php/php-src/blob/master/UPGRADING

// Replace
function test(int $arg = CONST_RESOLVING_TO_NULL) {}
// With
function test(?int $arg = CONST_RESOLVING_TO_NULL) {}
// Or
function test(int $arg = null) {}

?>

9.422.1. Suggestions

  • Use the valid syntax
Short name Functions/NullableWithConstant
Rulesets CompatibilityPHP80
Php Version 8.0-
Severity Minor
Time To Fix Quick (30 mins)
Precision High

9.423. Nullable Without Check

Nullable typehinted argument should be checked before usage.

<?php

// This will emit a fatal error when $a = null
function foo(?A $a) {
    return $a->m();
}

// This is stable
function foo(?A $a) {
    if ($a === null) {
        return 42;
    } else {
        return $a->m();
    }
}

?>

9.423.1. Suggestions

Short name Functions/NullableWithoutCheck
Rulesets ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.424. Numeric Literal Separator

Integer and floats may be written with internal underscores. This way, it is possible to separate large number into smaller groups, and make them more readable.

Numeric Literal Separators were introduced in PHP 7.4 and are not backward compatible.

<?php
$a = 1_000_000_000;   // A billion
$a = 1000000000;      // A billion too...

$b = 107_925_284.88; // 6 light minute to kilometers = 107925284.88 kilometers
$b = 107925284.88;   // Same as above
?>

See also PHP RFC: Numeric Literal Separator.

9.424.1. Suggestions

Short name Php/IntegerSeparatorUsage
Rulesets CompatibilityPHP73
Php Version 7.4+
Severity Minor
Time To Fix Quick (30 mins)

9.425. Objects Don’t Need References

There is no need to create references for objects, as those are always passed by reference when used as arguments.

Note that when the argument is assigned another value, including another object, then the reference is needed : PHP forgets about reference when they are replaced.

<?php

    $object = new stdClass();
    $object->name = 'a';

    foo($object);
    print $object->name; // Name is 'b'

    // No need to make $o a reference
    function foo(&$o) {
        $o->name = 'b';
    }


    // $o is assigned inside the function : it must be called with a &, or the object won't make it out of the foo3 scope
    function foo3(&$o) {
        $o = new stdClass;
    }

    $array = array($object);
    foreach($array as &$o) { // No need to make this a reference
        $o->name = 'c';
    }

?>

See also Passing by reference.

9.425.1. Suggestions

  • Remove the reference
  • Assign the argument with a new value
Short name Structures/ObjectReferences
Rulesets Analyze, Top10, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP no-references-on-objects
Examples Zencart, XOOPS

9.426. Old Style Constructor

PHP classes used to have the method bearing the same name as the class acts as the constructor. That was PHP 4, and early PHP 5.

The manual issues a warning about this syntax : Old style constructors are DEPRECATED in PHP 7.0, and will be removed in a future version. You should always use `__construct() <https://www.php.net/manual/en/language.oop5.decon.php>`_ in new code.

<?php

namespace {
    // Global namespace is important
    class foo {
        function foo() {
            // This acts as the old-style constructor, and is reported by PHP
        }
    }

    class bar {
        function __construct() { }
        function bar() {
            // This doesn't act as constructor, as bar has a __construct() method
        }
    }
}

namespace Foo\Bar{
    class foo {
        function foo() {
            // This doesn't act as constructor, as bar is not in the global namespace
        }
    }
}

?>

This is no more the case in PHP 5, which relies on __construct() to do so. Having this old style constructor may bring in confusion, unless you are also supporting old time PHP 4.

Note that classes with methods bearing the class name, but inside a namespace are not following this convention, as this is not breaking backward compatibility. Those are excluded from the analyze.

See also Constructors and Destructors.

9.426.1. Suggestions

  • Remove old style constructor and make it __construct()
  • Remove old libraries and use a modern component
Short name Classes/OldStyleConstructor
Rulesets Analyze, CompatibilityPHP80
Severity Minor
Time To Fix Quick (30 mins)
ClearPHP no-php4-class-syntax

9.427. Old Style __autoload()

Avoid __autoload(), only use spl_register_autoload().

__autoload() is deprecated since PHP 7.2 and possibly removed in later versions. spl_register_autoload() was introduced in PHP 5.1.0.

__autoload() may only be declared once, and cannot be modified later. This creates potential conflicts between libraries that try to set up their own autoloading schema.

On the other hand, spl_register_autoload() allows registering and de-registering multiple autoloading functions or methods.

<?php

// Modern autoloading.
function myAutoload($class){}
spl_register_autoload('myAutoload');

// Old style autoloading.
function __autoload($class){}

?>

Do not use the old __autoload() function, but rather the new spl_register_autoload() function.

See also Autoloading Classe.

9.427.1. Suggestions

  • Move to spl_register_autoload()
  • Remove usage of the old __autoload() function
  • Modernize usage of old libraries
Short name Php/oldAutoloadUsage
Rulesets Analyze
Severity Major
Time To Fix Instant (5 mins)
ClearPHP use-smart-autoload
Examples Piwigo

9.428. One If Is Sufficient

Nested conditions may be written another way, and reduce the amount of code.

Nested conditions are equivalent to a && condition. As such, they may be switched. When one of the condition has no explicit else, then it is lighter to write it as the first condition. This way, it is written once, and not repeated.

<?php

// Less conditions are written here.
     if($b == 2) {
        if($a == 1) {
             ++$c;
     }
        else {
             ++$d;
     }
    }

// ($b == 2) is double here
    if($a == 1) {
     if($b == 2) {
             ++$c;
     }
    }
    else {
     if($b == 2) {
             ++$d;
     }
    }
?>

9.428.1. Suggestions

  • Switch the if…then conditions, to reduce the amount of conditions to read.
Short name Structures/OneIfIsSufficient
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)
Examples Tikiwiki

9.429. One Letter Functions

One letter functions seems to be really short for a meaningful name. This may happens for very high usage functions, so as to keep code short, but such functions should be rare.

<?php

// Always use a meaningful name
function addition($a, $b) {
    return $a + $b;
}

// One letter functions are rarely meaningful
function f($a, $b) {
    return $a + $b;
}

?>

9.429.1. Suggestions

  • Use full names for functions
  • Remove the function name altogether : use a closure
Short name Functions/OneLetterFunctions
Rulesets Coding Conventions, Semantics
Severity Minor
Time To Fix Quick (30 mins)
Examples ThinkPHP, Cleverstyle

9.430. One Variable String

These strings only contains one variable or property or array.

<?php

$a = 0;
$b = "$a"; // This is a one-variable string

// Better way to write the above
$b = (string) $a;

// Alternatives :
$b2 = "$a[1]"; // This is a one-variable string
$b3 = "$a->b"; // This is a one-variable string
$c = "d";
$d = "D";
$b4 = "{$$c}";
$b5 = "{$a->foo()}";

?>

When the goal is to convert a variable to a string, it is recommended to use the type casting (string) operator : it is then clearer to understand the conversion. It is also marginally faster, though very little.

See also Strings and Type Juggling.

9.430.1. Suggestions

  • Drop the surrounding string, keep the variable (or property…)
  • Include in the string any concatenation that comes unconditionaly after or before
  • Convert the variable to a string with the (type) operator
Short name Type/OneVariableStrings
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples Tikiwiki, NextCloud

9.431. Only Variable For Reference

When a method is requesting an argument to be a reference, it cannot be called with a literal value.

The call must be made with a variable, or any assimilated data container : array, property or static property.

<?php

// This is not possible
foo(1,2);

// This is working
foo($a, $b);

function foo($a, &$b) {}

?>

Note that PHP may detect this error at linting time, if the method is defined after being called : at that point, PHP will only check the problem during execution. This is definitely the case for methods, compared to functions or static methods.

See also Passing arguments by reference.

9.431.1. Suggestions

  • Put the literal value in a variable before calling the method.
  • Put the literal value in the default value of the reference argument.
Short name Functions/OnlyVariableForReference
Rulesets Analyze, LintButWontExec
Severity Critical
Time To Fix Quick (30 mins)
Precision Medium

9.432. Only Variable Passed By Reference

When an argument is expected by reference, it is compulsory to provide a container. A container may be a variable, an array, a property or a static property.

This may be linted by PHP, when the function definition is in the same file as the function usage. This is silently linted if definition and usage are separated, if the call is dynamical or made as a method.

<?php

function foo(&$bar) { /**/ }

function &bar() { /**/ }

// This is not possible : strtolower() returns a value
foo(strtolower($string));

// This is valid : bar() returns a reference
foo(bar($string));

?>

This analysis currently covers functioncalls and static methodcalls, but omits methodcalls.

9.432.1. Suggestions

  • Store the previous result in a variable, and then call the function.
Short name Functions/OnlyVariablePassedByReference
Rulesets Analyze
Severity Critical
Time To Fix Slow (1 hour)
Examples Dolphin, PhpIPAM

9.433. Only Variable Returned By Reference

Function can’t return literals by reference.

When a function returns a reference, it is only possible to return variables, properties or static properties.

Anything else, like literals or static expressions, yield a warning at execution time.

<?php

// Can't return a literal number
function &foo() {
    return 3 + rand();
}

// bar must return values that are stored in a
function &bar() {
    $a = 3 + rand();
    return $a;
}

?>
Short name Structures/OnlyVariableReturnedByReference
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.434. Optimize Explode()

Limit explode() results at call time. explode() returns a string, after breaking it into smaller strings, with a delimiter.

By default, explode() breaks the whole string into smaller strings, and returns the array. When not all the elements of the returned array are necessary, using the third argument of explode() speeds up the process, by removing unnecessary work.

<?php

$string = '1,2,3,4,5,';

// explode() returns 2 elements, which are then assigned to the list() call.
list($a, $b) = explode(',', $string, 2);

// explode() returns 6 elements, only two of which are then assigned to the list() call. The rest are discarded.
list($a, $b) = explode(',', $string, 2);

// it is not possible to skip the first elements, but it is possible to skip the last ones.
echo explode(',', $string, 2)[1];

// This protects PHP, in case $string ends up with a lot of commas
$string = foo(); // usually '1,2' but not known
list($a, $b) = explode(',', $string, 2);
?>

Limiting explode() has no effect when the operation is already exact : it simply prevents explode() to cut more than needed if the argument is unexpectedly large.

This optimisation applies to preg_split() and mb_split() too.

This is a micro optimisation, unless the exploded string is large.

9.434.1. Suggestions

  • Add a limit to explode() call
Short name Performances/OptimizeExplode
Rulesets Performances
Severity Minor
Time To Fix Quick (30 mins)
Precision Very high

9.435. Or Die

Classic old style failed error management.

<?php

// In case the connexion fails, this kills the current script
mysql_connect('localhost', $user, $pass) or die();

?>

Interrupting a script will leave the application with a blank page, will make your life miserable for testing. Just don’t do that.

See also pg_last_error or PDO::exec.

9.435.1. Suggestions

  • Throw an exception
  • Trigger an error with trigger_error()
  • Use your own error mechanism
Short name Structures/OrDie
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
ClearPHP no-implied-if
Examples Tine20, OpenConf

9.436. Order Of Declaration

The order used to declare members and methods has a great impact on readability and maintenance. However, practices varies greatly. As usual, being consistent is the most important and useful.

The suggested order is the following : traits, constants, properties, methods. Optional characteristics, like final, static… are not specified. Special methods names are not specified.

<?php

class x {
    use traits;

    const CONSTANTS = 1;
    const CONSTANTS2 = 1;
    const CONSTANTS3 = 1;

    private $property = 2;
    private $property2 = 2;
    private $property3 = 2;

    public function foo() {}
    public function foo2() {}
    public function foo3() {}
    public function foo4() {}
}

?>
Short name Classes/OrderOfDeclaration
Rulesets Coding Conventions

9.437. Overwritten Exceptions

In catch blocks, it is good practice to avoid overwriting the incoming exception, as information about the exception will be lost.

<?php

try {
    doSomething();
} catch (SomeException $e) {
    // $e is overwritten
    $e = new anotherException($e->getMessage());
    throw $e;
} catch (SomeOtherException $e) {
    // $e is chained with the next exception
    $e = new Exception($e->getMessage(), 0, $e);
    throw $e;
}

?>

9.437.1. Suggestions

  • Use another variable name to create new values inside the catch
  • Use anonymous catch clause (no variable caught) in PHP 8.0, to make this explicit
Short name Exceptions/OverwriteException
Rulesets Analyze, Suggestions, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.438. Overwritten Literals

The same variable is assigned a literal twice. It is possible that one of the assignation is too much.

This analysis doesn’t take into account the distance between two assignations : it may report false positives when the variable is actually used for several purposes, and, as such, assigned twice with different values.

<?php

function foo() {
    // Two assignations in a short sequence : one is too many.
    $a = 1;
    $a = 2;

    for($i = 0; $i < 10; $i++) {
        $a += $i;
    }
    $b = $a;

    // New assignation. $a is now used as an array.
    $a = array(0);
}

?>
Short name Variables/OverwrittenLiterals
Rulesets Analyze
Severity Major
Time To Fix Instant (5 mins)

9.439. Overwritten Source And Value

In a foreach(), it is best to keep source and values distinct. Otherwise, they overwrite each other.

Since PHP 7.0, PHP makes a copy of the original source, then works on it. This makes possible to use the same name for the source and the values.

<?php

// displays 0-1-2-3-3
$array = range(0, 3);
foreach($array as $array) {
    print $array . '-';
}
print_r($array);


/* displays 0-1-2-3-Array
(
    [0] => 0
    [1] => 1
    [2] => 2
    [3] => 3
)
*/
$array = range(0, 3);
foreach($array as $v) {
    print $v . '-';
}
print_r($array);

?>

When the source is used as the value, the elements in the array are successively assigned to itself. After the loop, the original array has been replaced by its last element.

The same applies to the index, or to any variable in a list() structure, used in a foreach().

9.439.1. Suggestions

  • Keep the source, the index and the values distinct
Short name Structures/ForeachSourceValue
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples ChurchCRM, ExpressionEngine

9.440. PHP 7.0 New Classes

Those classes are now declared natively in PHP 7.0 and should not be declared in custom code.

There are 8 new classes :

  • Error
  • ParseError
  • TypeError
  • ArithmeticError
  • DivisionByZeroError
  • ClosedGeneratorException
  • ReflectionGenerator
  • ReflectionType
  • AssertionError
<?php

namespace {
    // Global namespace
    class Error {
        // Move to a namespace
        // or, remove this class
    }
}

namespace B {
    class Error {
        // This is OK : in a namespace
    }
}

?>

See also New Classes and Interfaces.

Short name Php/Php70NewClasses
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Slow (1 hour)

9.441. PHP 7.0 New Interfaces

The following interfaces are introduced in PHP 7.0. They shouldn’t be defined in custom code.

Short name Php/Php70NewInterfaces
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Slow (1 hour)

9.442. PHP 7.0 Removed Directives

List of directives that are removed in PHP 7.0.

Short name Php/Php70RemovedDirective
Rulesets CompatibilityPHP70, CompatibilityPHP71
Php Version With PHP 7.0 and more recent
Severity Major
Time To Fix Slow (1 hour)

9.443. PHP 7.0 Removed Functions

The following PHP native functions were removed in PHP 7.0.

This analysis skips redefined PHP functions : when a replacement for a removed PHP function was created, with condition on the PHP version, then its usage is considered valid.

See also PHP 7.0 Removed Functions.

9.443.1. Suggestions

  • Replace the old functions with modern functions
  • Remove the usage of the old functions
  • Create an alternative function by wiring the old name to a new feature
Short name Php/Php70RemovedFunctions
Rulesets CompatibilityPHP70, CompatibilityPHP71
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Slow (1 hour)

9.444. PHP 7.0 Scalar Typehints

New scalar typehints were introduced : bool, int, float, string.

They cannot be used before PHP 7.0, and will be confused with classes or interfaces.

<?php

function foo(string $name) {
    print Hello $name;
}

foo(Damien);
// display 'Hello Damien'

foo(33);
// displays an error

?>

See also Scalar type declarations, and PHP 7 SCALAR TYPE DECLARATIONS.

Short name Php/PHP70scalartypehints
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and more recent
Severity Critical
Time To Fix Quick (30 mins)

9.445. PHP 7.1 Microseconds

PHP supports microseconds in DateTime class and date_create() function. This was introduced in PHP 7.1.

In previous PHP versions, those dates only used seconds, leading to lazy comparisons :

<?php

$now = date_create();
usleep(10);              // wait for 0.001 ms
var_dump($now == date_create());

?>

This code displays true in PHP 7.0 and older, (unless the code was run too close from the next second). In PHP 7.1, this is always false.

This is also true with DateTime :

<?php

$now = new DateTime();
usleep(10);              // wait for 0.001 ms
var_dump((new DateTime())->format('u') == $now->format('u'));

?>

This evolution impacts mostly exact comparisons (== and ===). Non-equality (!= and !==) will probably be always true, and should be reviewed.

See also Backward incompatible changes.

Short name Php/Php71microseconds
Rulesets CompatibilityPHP71
Severity Major
Time To Fix Quick (30 mins)

9.446. PHP 7.1 Removed Directives

List of directives that are removed in PHP 7.1.

Short name Php/Php71RemovedDirective
Rulesets CompatibilityPHP71
Php Version With PHP 7.1 and more recent
Severity Major
Time To Fix Slow (1 hour)

9.447. PHP 7.1 Scalar Typehints

A new scalar typehint was introduced : iterable.

It can’t be used before PHP 7.1, and will be confused with classes or interfaces.

<?php

function foo(iterable $iterable) {
    foreach ($iterable as $value) {
        echo $value.PHP_EOL;
    }
}

foo(range(1,20));
// works with array

foo(new ArrayIterator([1, 2, 3]));
// works with an iterator

foo((function () { yield 1; })() );
// works with a generator

?>

See also iterable pseudo-type, and The iterable Pseudo-Type.

Short name Php/PHP71scalartypehints
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.1 and more recent
Severity Critical
Time To Fix Quick (30 mins)

9.448. PHP 7.2 Deprecations

Several functions are deprecated in PHP 7.2.

Deprecated functions and extensions are reported in a separate analysis.

See also Deprecations for PHP 7.2.

9.448.1. Suggestions

  • Remove the deprecated functions, and replace them with a new feature
  • Use a replacement function to emulate this old behavior
Short name Php/Php72Deprecation
Rulesets CompatibilityPHP72
Php Version With PHP 7.2 and older
Severity Major
Time To Fix Slow (1 hour)

9.449. PHP 7.2 Object Keyword

‘object’ is a PHP keyword. It can’t be used for class, interface or trait name.

This is the case since PHP 7.2.

<?php

// Valid until PHP 7.2
class object {}

// Altough it is really weird anyway...

?>

See also List of Keywords.

Short name Php/Php72ObjectKeyword
Rulesets CompatibilityPHP72
Php Version With PHP 7.2 and older
Severity Major
Time To Fix Quick (30 mins)

9.450. PHP 7.2 Removed Functions

The following PHP native functions were removed in PHP 7.2.

This analysis skips redefined PHP functions : when a replacement for a removed PHP function was created, with condition on the PHP version, then its usage is considered valid.

See also Deprecated features in PHP 7.2.x.

Short name Php/Php72RemovedFunctions
Rulesets CompatibilityPHP72
Php Version With PHP 7.2 and older
Severity Major
Time To Fix Slow (1 hour)

9.451. PHP 7.2 Scalar Typehints

A new scalar typehint was introduced : object.

It can’t be used before PHP 7.2, and will be confused with classes or interfaces.

<?php

function test(object $obj) : object
{
    return new SplQueue();
}

test(new StdClass());

?>

See also New object type, and PHP 7.2 and Object Typehint.

Short name Php/PHP72scalartypehints
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.2 and more recent
Severity Critical
Time To Fix Quick (30 mins)

9.452. PHP 7.3 Last Empty Argument

PHP allows the last element of any functioncall to be empty. The argument is then not send.

This was introduced in PHP 7.3, and is not backward compatible.

The last empty line is easier on the VCS, allowing clearer text diffs.

<?php

function foo($a, $b) {
    print_r(func_get_args());
}


foo(1,
    2,
    );

foo(1);


?>

See also Allow a trailing comma in function calls and Trailing commas.

Short name Php/PHP73LastEmptyArgument
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.3 and more recent
Severity Critical
Time To Fix Quick (30 mins)

9.453. PHP 7.3 Removed Functions

The following PHP native functions were removed in PHP 7.3.

This analysis skips redefined PHP functions : when a replacement for a removed PHP function was created, with condition on the PHP version, then its usage is considered valid.

See also PHP 7.3 Removed Functions.

Short name Php/Php73RemovedFunctions
Rulesets CompatibilityPHP73
Php Version With PHP 7.3 and older
Severity Critical
Time To Fix Slow (1 hour)

9.454. PHP 7.4 Constant Deprecation

One constant is deprecated in PHP 7.4.

  • CURLPIPE_HTTP1

See also Deprecations for PHP 7.2.

9.454.1. Suggestions

  • Use CURLPIPE_MULTIPLEX or CURLPIPE_NOTHING
Short name Php/Php74Deprecation
Rulesets CompatibilityPHP74
Php Version With PHP 7.4 and older
Severity Major
Time To Fix Slow (1 hour)

9.455. PHP 7.4 Removed Directives

List of directives that are removed in PHP 7.4.

  • allow_url_include

See Deprecation allow_url_include.

9.455.1. Suggestions

  • Stop using this directive
Short name Php/Php74RemovedDirective
Rulesets CompatibilityPHP74
Php Version 7.4+
Severity Minor
Time To Fix Quick (30 mins)

9.456. PHP 7.4 Removed Functions

The following PHP native functions were deprecated in PHP 7.4.

This analysis skips redefined PHP functions : when a replacement for a removed PHP function was created, with condition on the PHP version, then its usage is considered valid.

See also PHP 7.4 Removed Functions and PHP 7.4 Deprecations : Introduction.

9.456.1. Suggestions

Short name Php/Php74RemovedFunctions
Rulesets CompatibilityPHP74
Php Version With PHP 7.3 and older
Severity Critical
Time To Fix Slow (1 hour)
Precision Very high

9.457. PHP 7.4 Reserved Keyword

fn is a new PHP keyword. In PHP 7.4, it is used to build the arrow functions. When used at an illegal position, fn generates a Fatal error at compile time.

As a key word, fn is not allowed as constant name, function name, class name or inside namespaces.

<?php

// PHP 7.4 usage of fn
function array_values_from_keys($arr, $keys) {
    return array_map(fn($x) => $arr[$x], $keys);
}

// PHP 7.3 usage of fn
const fn = 1;

function fn() {}

class x {
    // This is valid in PHP 7.3 and 7.4
    function fn() {}
}

?>

fn is fine for method names. It may also be used for constants with define(), and constant() but it is not recommended.

See also PHP RFC: Arrow Functions.

9.457.1. Suggestions

Short name Php/Php74ReservedKeyword
Rulesets CompatibilityPHP74
Php Version 7.4-
Severity Minor
Time To Fix Quick (30 mins)

9.458. PHP 74 New Directives

List of directives that are new in PHP 7.4.

  • zend.exception_ignore_args : From the php.ini : Allows to include or exclude arguments from stack traces generated for exceptions. Default: Off
  • opcache.preload_user

See RFC Preload.

9.458.1. Suggestions

  • Do not use those directives with PHP before version 7.4
Short name Php/Php74NewDirective
Rulesets CompatibilityPHP73
Php Version 7.4-
Severity Minor
Time To Fix Quick (30 mins)

9.459. PHP 8.0 Removed Constants

The following PHP native constants were removed in PHP 8.0.

9.459.1. Suggestions

  • Remove usage of INTL_IDNA_VARIANT_2003 and use
Short name Php/Php80RemovedConstant
Rulesets CompatibilityPHP80
Severity Critical
Time To Fix Quick (30 mins)

9.460. PHP 8.0 Removed Directives

List of directives that are removed in PHP 8.0.

In PHP 8.0, track_errors was removed.

You can detect valid directives with ini_get(). This native function will return false, when the directive doesn’t exist, while actual directive values will be returned as a string.

9.460.1. Suggestions

  • Remove usage of track_errors.
Short name Php/Php80RemovedDirective
Rulesets CompatibilityPHP80
Severity Minor
Time To Fix Quick (30 mins)

9.461. PHP 8.0 Removed Functions

The following PHP native functions were removed in PHP 8.0.

Short name Php/Php80RemovedFunctions
Rulesets CompatibilityPHP80
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Slow (1 hour)

9.462. PHP Keywords As Names

PHP has a set of reserved keywords. It is recommended not to use those keywords for names structures.

PHP does check that a number of structures, such as classes, methods, interfaces… can’t be named or called using one of the keywords. However, in a few other situations, no check are enforced. Using keywords in such situation is confusing.

<?php

// This keyword is reserved since PHP 7.2
class object {
    // _POST is used by PHP for the $_POST variable
    // This methods name is probably confusing,
    // and may attract more than its share of attention
    function _POST() {

    }
}

?>

See also List of Keywords, Predefined Classes, Predefined Constants, List of other reserved words and Predefined Variables.

9.462.1. Suggestions

  • Rename the structure
  • Choose another naming convention to avoid conflict and rename the current structures
Name Default Type Description
reservedNames   string Other reserved names : all in a string, comma separated.
allowedNames   string PHP reserved names that can be used in the code. All in a string, comma separated.
Short name Php/ReservedNames
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)
Examples ChurchCRM, xataface

9.463. PHP5 Indirect Variable Expression

Indirect variable expressions changes between PHP 5 an 7.

The following structures are evaluated differently in PHP 5 and 7. It is recommended to review them or switch to a less ambiguous syntax.

<?php

// PHP 7
$foo = 'bar';
$bar['bar']['baz'] = 'foobarbarbaz';
echo $$foo['bar']['baz'];
echo ($$foo)['bar']['baz'];

// PHP 5
$foo['bar']['baz'] = 'bar';
$bar = 'foobarbazbar';
echo $$foo['bar']['baz'];
echo ${$foo['bar']['baz']};

?>

See Backward incompatible changes PHP 7.0

Expression PHP 5 interpretation PHP 7 interpretation
$$foo[‘bar’][‘baz’] $foo->$bar[‘baz’] $foo->$bar[‘baz’]() Foo::$bar[‘baz’]() ${$foo[‘bar’][‘baz’]} $foo->{$bar[‘baz’]} $foo->{$bar[‘baz’]}() Foo::{$bar[‘baz’]}() ($$foo)[‘bar’][‘baz’] ($foo->$bar)[‘baz’] ($foo->$bar)[‘baz’]() (Foo::$bar)[‘baz’]()

9.463.1. Suggestions

  • Avoid using complex expressions, mixing $$\, [0] and -> in the same expression
  • Add curly braces {} to ensure that the precedence is the same between PHP 5 and 7. For example, $$v becomes ${$v}
Short name Variables/Php5IndirectExpression
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Slow (1 hour)

9.464. PHP7 Dirname

With PHP 7, dirname() has a second argument that represents the number of parent folder to follow. This prevent us from using nested dirname() calls to reach an grand-parent direct.

<?php
$path = '/a/b/c/d/e/f';

// PHP 7 syntax
$threeFoldersUp = dirname($path, 3);

// PHP 5 syntax
$threeFoldersUp = dirname(dirname(dirname($path)));

?>

See also dirname.

9.464.1. Suggestions

  • Use dirname()’s second argument
Short name Structures/PHP7Dirname
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56, Suggestions, php-cs-fixable
Php Version 7.0+
Severity Minor
Time To Fix Quick (30 mins)
Examples OpenConf, MediaWiki

9.465. Parameter Hiding

When a parameter is set to another variable, and never used.

While this is a legit syntax, parameter hiding tends to make the code confusing. The parameter itself seems to be unused, while some extra variable appears.

Keep this code simple by removing the hiding parameter.

<?php

function substract($a, $b) {
    // $b is given to $c;
    $c = $b;

    $c is used, but $b would be the same
    return $a - $c;
}

?>

9.465.1. Suggestions

  • Remove the hiding parameter
Short name Functions/ParameterHiding
Rulesets Semantics
Severity Minor
Time To Fix Quick (30 mins)

9.466. Parent First

When calling parent constructor, always put it first in the __construct method. It ensures the parent is correctly build before the child start using values.

<?php

class father {
    protected $name = null;

    function __construct() {
        $this->name = init();
    }
}

class goodSon {
    function __construct() {
        // parent is build immediately,
        parent::__construct();
        echo my name is.$this->name;
    }
}

class badSon {
    function __construct() {
        // This will fail.
        echo my name is.$this->name;

        // parent is build later,
        parent::__construct();
    }
}

?>

This analysis doesn’t apply to Exceptions.

9.466.1. Suggestions

  • Use parent\:\:__construct as the first call in the constructor.
Short name Classes/ParentFirst
Rulesets Analyze, Suggestions
Severity Minor
Time To Fix Quick (30 mins)
Examples shopware, PrestaShop

9.467. Parent, Static Or Self Outside Class

Parent, static and self keywords must be used within a class or a trait. They make no sens outside a class or trait scope, as self and static refers to the current class and parent refers to one of parent above.

PHP 7.0 and later detect their usage at compile time, and emits a fatal error.

<?php

class x {
    const Y = 1;

    function foo() {
        // self is \x
        echo self::Y;
    }
}

const Z = 1;
// This lint but won't anymore
echo self::Z;

?>

Static may be used in a function or a closure, but not globally.

Short name Classes/PssWithoutClass
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.468. Parenthesis As Parameter

Using parenthesis around parameters used to silent some internal check. This is not the case anymore in PHP 7, and should be fixed by removing the parenthesis and making the value a real reference.

<?php

// PHP 7 sees through parenthesis
$d = foo(1, 2, $c);

// Avoid parenthesis in arguments
$d = foo(1, 2, ($c));

?>

9.468.1. Suggestions

  • Remove the parenthesis when they are only encapsulating an argument
Short name Php/ParenthesisAsParameter
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Severity Major
Time To Fix Quick (30 mins)

9.469. Pathinfo() Returns May Vary

pathinfo() function returns an array whose content may vary. It is recommended to collect the values after check, rather than directly.

<?php

$file = '/a/b/.c';
//$extension may be missing, leading to empty $filename and filename in $extension
list( $dirname, $basename, $extension, $filename ) = array_values( pathinfo($file) );

//Use PHP 7.1 list() syntax to assign correctly the values, and skip array_values()
//This emits a warning in case of missing index
['dirname'   => $dirname,
 'basename'  => $basename,
 'extension' => $extension,
 'filename'  => $filename ] = pathinfo($file);

//This works without warning
$details = pathinfo($file);
$dirname   = $details['dirname'] ?? getpwd();
$basename  = $details['basename'] ?? '';
$extension = $details['extension'] ?? '';
$filename  = $details['filename'] ?? '';

?>

The same applies to parse_url(), which returns an array with various index.

9.469.1. Suggestions

  • Add a check on the return value of pathinfo() before using it.
Short name Php/PathinfoReturns
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples NextCloud

9.470. Php 7 Indirect Expression

Those are variable indirect expressions that are interpreted differently in PHP 5 and PHP 7.

You should check them so they don’t behave strangely.

<?php

// Ambiguous expression :
$b = $$foo['bar']['baz'];
echo $b;

$foo = array('bar' => array('baz' => 'bat'));
$bat = 'PHP 5.6';

// In PHP 5, the expression above means :
$b = $\{$foo['bar']['baz']};
$b = 'PHP 5.6';

$foo = 'a';
$a = array('bar' => array('baz' => 'bat'));

// In PHP 7, the expression above means :
$b = ($$foo)['bar']['baz'];
$b = 'bat';

?>

See also Changes to variable handling.

9.470.1. Suggestions

  • Avoid using complex expressions, mixing $$, [0] and -> in the same expression
  • Add curly braces {} to ensure that the precedence is the same between PHP 5 and 7. For example, $$v becomes ${$v}
Short name Variables/Php7IndirectExpression
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56, CompatibilityPHP70
Php Version With PHP 7.0 and more recent
Severity Major
Time To Fix Slow (1 hour)

9.471. Php 7.1 New Class

New classes, introduced in PHP 7.1. If classes where created with the same name, in current code, they have to be moved in a namespace, or removed from code to migrate safely to PHP 7.1.

The new class is : ReflectionClassConstant. The other class is ‘Void’ : this is forbidden as a class name, as Void is used for return type hint.

<?php

class ReflectionClassConstant {
    // Move to a namespace, do not leave in global
    // or, remove this class
}

?>
Short name Php/Php71NewClasses
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.1 and older
Severity Major
Time To Fix Slow (1 hour)

9.472. Php 7.2 New Class

New classes, introduced in PHP 7.2. If classes where created with the same name, in current code, they have to be moved in a namespace, or removed from code to migrate safely to PHP 7.2.

The new class is : HashContext.

<?php

namespace {
    // Global namespace
    class HashContext {
        // Move to a namespace
        // or, remove this class
    }
}

namespace B {
    class HashContext {
        // This is OK : in a namespace
    }
}

?>
Short name Php/Php72NewClasses
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56, CompatibilityPHP72
Php Version With PHP 7.2 and older
Severity Major
Time To Fix Slow (1 hour)

9.473. Php 7.4 New Class

New classes, introduced in PHP 7.4. If classes where created with the same name, in current code, they have to be moved in a namespace, or removed from code to migrate safely to PHP 7.4.

The new classes are :

  • ReflectionReference
  • WeakReference
<?php

namespace {
    // Global namespace
    class WeakReference {
        // Move to a namespace
        // or, remove this class
    }
}

namespace B {
    class WeakReference {
        // This is OK : in a namespace
    }
}

?>

9.473.1. Suggestions

  • Move the current classes with the same names into a distinct domain name
Short name Php/Php74NewClasses
Rulesets CompatibilityPHP74
Php Version With PHP 7.2 and older
Severity Major
Time To Fix Slow (1 hour)

9.474. Php 8.0 Only TypeHints

Two scalar typehints are introduced in version 8. They are false and null. In PHP 7.0, both those values could not be used as a class or interface name, to avoid confusion with the actual booleans, nor null value.

false represents a false boolean, and nothing else. It is more restrictive than a boolean, which accepts true too. null is an alternative syntax to ? : it allows the type to be null.

Both the above typehints are to be used in cunjunction with other types : they can’t be used alone.

<?php

// function accepts an A object, or null.
function foo(A|null $x) {}

// same as above
function foo2(A|null $x) {}

// returns an object of class B, or false
function bar($x) : false|B {}

?>

See also PHP RFC: Union Types 2.0.

9.474.1. Suggestions

Short name Php/Php80OnlyTypeHints
Rulesets CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP73, CompatibilityPHP74, CompatibilityPHP56
Severity Minor
Time To Fix Quick (30 mins)

9.475. Php 8.0 Variable Syntax Tweaks

Several variable syntaxes are added in version 8.0. They extends the PHP 7.0 syntax updates, and fix a number of edges cases.

In particular, new``and ``instanceof now support a way to inline the expression, rather than use a temporary variable.

Magic constants are now accessible with array notation, just like another constant. It is also possible to use method calls : although this is Syntacticly correct for PHP, this won’t be executed, as the left operand is a string, and not an object.

<?php

 // array name is dynamically build
 echo foo$bar[0];
 // static method
 foo$bar::baz();
 // static property
 foo$bar::$baz;

 // Syntactly correct, but not executable
 foo$bar->baz();

 // expressions with instanceof and new
    $object = new (class_.$name);
    $x instanceof (class_$name);

    // PHP 7.0 style
    $className = class_.$name;
    $object = new $className;

?>

See also PHP RFC: Variable Syntax Tweaks and scalar_objects in PHP.

Short name Php/Php80VariableSyntax
Rulesets CompatibilityPHP74
Php Version 8.0+
Severity Major
Time To Fix Quick (30 mins)

9.476. Php/UseMatch

9.476.1. Suggestions

Short name Php/UseMatch
Rulesets CompatibilityPHP74
Php Version 8.0+
Severity Minor
Time To Fix Quick (30 mins)

9.477. Php7 Relaxed Keyword

Most of the traditional PHP keywords may be used inside classes, trait or interfaces.

<?php

// Compatible with PHP 7.0 +
class foo {
    // as is a PHP 5 keyword
    public function as() {

    }
}

?>

This was not the case in PHP 5, and will yield parse errors.

See also Loosening Reserved Word Restrictions.

Short name Php/Php7RelaxedKeyword
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and more recent
Severity Major
Time To Fix Slow (1 hour)

9.478. Phpinfo

phpinfo() is a great function to learn about the current configuration of the server.

<?php

if (DEBUG) {
    phpinfo();
}

?>

If left in the production code, it may lead to a critical leak, as any attacker gaining access to this data will know a lot about the server configuration.

It is advised to never leave that kind of instruction in a production code.

phpinfo() may be necessary to access some specific configuration of the server : for example, Apache module list are only available via phpinfo(), and apache_get(), when they are loaded.

9.478.1. Suggestions

  • Remove all usage of phpinfo()
  • Add one or more constant to fine-tune the phpinfo(), and limit the amount of displayed information
  • Replace phpinfo() with a more adapted method : get_loaded_extensions() to access the list of loaded extensions
Short name Structures/PhpinfoUsage
Rulesets Security
Severity Major
Time To Fix Quick (30 mins)
Examples Dolphin

9.479. Possible Alias Confusion

An alias is used for a class that doesn’t belong to the current namespace, while there is such a class. This also applies to traits and interfaces.

When no alias is used, PHP will search for a class in the local space. Since classes, traits and interfaces are usually stored one per file, it is a valid syntax to create an alias, even if this alias name is the name of a class in the same namespace.

Yet, with an alias refering to a remote class, while a local one is available, it is possible to generate confusion.

<?php

// This should be in a separate file, but has been merged here, for display purposes.
namespace A {
    //an alias from a namespace called C
    use C\A as C_A;

    //an alias from a namespace called C, which will superseed the local A\B class (see below)
    use C\D as B;
}

namespace A {
    // There is a class B in the A namespace
    class B {}
}

?>

9.479.1. Suggestions

  • Avoid using existing classes names for alias
  • Use a coding convention to distinguish alias from names
Short name Namespaces/AliasConfusion
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.480. Possible Increment

This expression looks like a typo : a missing + would change the behavior.

The same pattern is not reported with -, as it is legit expression. + sign is usually understated, rather than explicit.

<?php

// could it be a ++$b ?
$a = +$b;

?>

See also Incrementing/Decrementing Operators and Arithmetic Operators.

9.480.1. Suggestions

  • Drop the whole assignation
  • Complete the addition with another value : $a = 1 + $b
  • Make this a ++ operator : ++$b
  • Make this a negative operator : -$b
  • Make the casting explicit : (int) $b
Short name Structures/PossibleIncrement
Rulesets Suggestions
Severity Minor
Time To Fix Instant (5 mins)
Examples Zurmo, MediaWiki

9.481. Possible Infinite Loop

Loops on files that can’t be open results in infinite loop.

fgets(), and functions like fgetss(), fgetcsv(), fread(), return false when they finish reading, or can’t access the file.

In case the file is not accessible, comparing the result of the reading to something that is falsy, leads to a permanent valid condition. The execution will only finish when the max_execution_time is reached.

<?php

$file = fopen('/path/to/file.txt', 'r');
// when fopen() fails, the next loops is infinite
// fgets() will always return false, and while will always be true.
while($line = fgets($file) != 'a') {
    doSomething();
}

?>

It is recommended to check the file resources when they are opened, and always use === or !== to compare readings. feof() is also a reliable function here.

Short name Structures/PossibleInfiniteLoop
Rulesets Analyze
Severity Critical
Time To Fix Quick (30 mins)

9.482. Possible Missing Subpattern

When capturing subpatterns are the last ones in a regex, PHP doesn’t fill their spot in the resulting array. This leads to a possible missing index in the result array.

<?php

// displays a partial array, from 0 to 1
preg_match('/(a)(b)?/', 'adc', $r);
print_r($r);
/*
Array
(
    [0] => a
    [1] => a
)
*/

// displays a full array, from 0 to 2
preg_match('/(a)(b)?/', 'abc', $r);
print_r($r);

/*
Array
(
    [0] => ab
    [1] => a
    [2] => b
)
*/

// double 'b' when it is found
print preg_replace(',^a(b)?,', './$1$1', 'abc'); // prints ./abbc
print preg_replace(',^a(b)?,', './$1$1', 'adc'); // prints ./dc

?>

?>

The same applies to preg_replace() : the pattern may match the string, but no value is available is the corresponding sub-pattern.

In PHP 7.4, a new option was added : PREG_UNMATCHED_AS_NULL, which always provides a value for the subpatterns.

See also Bug #50887 preg_match , last optional sub-patterns ignored when empty and Bug #73948 Preg_match_all should return NULLs on trailing optional capture groups..

9.482.1. Suggestions

  • Add an always capturing subpatterns after the last ?
  • Move the ? inside the parenthesis, so the parenthesis is always on, but the content may be empty
  • Add a test on the last index of the resulting array, to ensure it is available when needed
  • Use the PREG_UNMATCHED_AS_NULL option (PHP 7.4+)
Short name Php/MissingSubpattern
Rulesets Analyze, Top10, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples phpMyAdmin, SPIP

9.483. Pre-increment

When possible, use the pre-increment operator (++$i or --$i) instead of the post-increment operator ($i++ or $i--).

The latter needs an extra memory allocation that costs about 10% of performances.

<?php

// ++$i should be preferred over $i++, as current value is not important
for($i = 0; $i <10; ++$i) {
    // do Something
}

// ++$b and $b++ have different impact here, since $a will collect $b + 1 or $b, respectively.
$a = $b++;

?>

This is a micro-optimisation. However, its usage is so widespread, including within loops, that it may eventually have an significant impact on execution time. As such, it is recommended to adopt this rule, and only consider changing legacy code as they are refactored for other reasons.

9.483.1. Suggestions

  • Use the pre increment when the new value is not reused.
Short name Performances/PrePostIncrement
Rulesets Analyze, Performances, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples ExpressionEngine, Traq

9.484. Prefix And Suffixes With Typehint

This analysis checks the relationship between methods prefixes and suffixes, with their corresponding return typehint.

For example, a method with the signature function isACustomer() {} should return a boolean. That boolean can then be read when calling the method : if ($user->isACustomer()) {}.

There are multiple such convention that may be applied. For example, has* should return a boolean, set* should return nothing (a.k.a void), and ``get*``shall return any kind of type.

<?php

class x  {
    // Easy to read convention
    function isAUser() : bool {}

    // shall return a boolean
    function isACustomer() {}

    // shall return a string, based on suffix 'name => string'
    function getName() {}

    // shall return a string, based on suffix 'name => string'
    function getUsername() {}

    // shall return \Uuid, based on prefix 'uuid => \Uuid'
    function getUuid() {}

    // shall return anything, based on no prefix nor suffix
    function getBirthday() {}

}

?>

There are 2 parameters for this analysis. It is recommended to customize them to get an better results, related to the naming conventions used in the code.

prefixedType is used for prefix in method names, which is the beginning of the name. suffixedType is used for suffixes : the ending part of the name. Matching is case insensitive.

The prefix is configured as the index of the map, while the related type is configured as the value of the map.

prefixToType['is'] = 'bool'; will be use as is* shall use the bool typehint.

Multiple typehints may be used at the same time. PHP supports multiple types since PHP 8.0, and Exakat will support them with any PHP version. Specify multiple types by separating them with comma. Any typehint not found in this list will be reported, including null.

PHP scalar types are available : string, int, void, etc. Explicit types, based on classes or interfaces, must use the fully qualified name, not the short name. suffixToType['uuid'] = '\Uuid'; will be use as *uuid shall use the \Uuid typehint.

When multiple rules applies, only one is reported.

9.484.1. Suggestions

Name Default Type Description
prefixedType prefixedType[‘is’] = ‘bool’; prefixedType[‘has’] = ‘bool’; prefixedType[‘set’] = ‘void’; prefixedType[‘list’] = ‘array’; ini_hash List of prefixes and their expected returntype
suffixedType prefixedType[‘list’] = ‘bool’; prefixedType[‘int’] = ‘int’; prefixedType[‘string’] = ‘string’; prefixedType[‘name’] = ‘string’; prefixedType[‘description’] = ‘string’; prefixedType[‘id’] = ‘int’; prefixedType[‘uuid’] = ‘Uuid’; ini_hash List of suffixes and their expected returntype
Short name Functions/PrefixToType
Rulesets Semantics
Severity Minor
Time To Fix Quick (30 mins)

9.485. Preprocess Arrays

Using long list of assignations for initializing arrays is significantly slower than the declaring them as an array.

<?php

// Slow way
$a = []; // also with $a = array();
$a[1] = 2;
$a[2] = 3;
$a[3] = 5;
$a[4] = 7;
$a[5] = 11;

// Faster way
$a = [1 => 2,
      2 => 3,
      3 => 5,
      4 => 7,
      5 => 11];

// Even faster way if indexing is implicit
$a = [2, 3, 5, 7, 11];

?>

If the array has to be completed rather than created, it is also faster to use += when there are more than ten elements to add.

<?php

// Slow way
$a = []; // also with $a = array();
$a[1] = 2;
$a[2] = 3;
$a[3] = 5;
// some expressions to get $seven and $eleven
$a[4] = $seven;
$a[5] = $eleven;

// Faster way
$a = [1 => 2,
      2 => 3,
      3 => 5];
// some expressions to get $seven and $eleven
$a += [4 => $seven,
       5 => $eleven];

// Even faster way if indexing is implicit
$a = [2, 3, 5];
// some expressions to get $seven and $eleven
$a += [$seven, $eleven];

?>

9.485.1. Suggestions

  • Preprocess the code so PHP doesn’t do it. Keep the detailed version into comments.
Short name Arrays/ShouldPreprocess
Rulesets none
Severity Minor
Time To Fix Quick (30 mins)

9.486. Preprocessable

The following expression are made of literals or already known values : they may be fully calculated before running PHP.

<?php

// Building an array from a string
$name = 'PHP'.' '.'7.2';

// Building an array from a string
$list = explode(',', 'a,b,c,d,e,f');

// Calculating a power
$kbytes = $bytes / pow(2, 10);

// This will never change
$name = ucfirst(strtolower('PARIS'));

?>

By doing so, this will reduce the amount of work of PHP.

9.486.1. Suggestions

  • Do the work yourself, instead of giving it to PHP
Short name Structures/ShouldPreprocess
Rulesets Analyze, Suggestions, Suggestions, Rector
Severity Minor
Time To Fix Instant (5 mins)
Examples phpadsnew

9.488. Printf Number Of Arguments

The number of arguments provided to printf() or vprintf() doesn’t match the format string.

Extra arguments are ignored, and are dead code as such. Missing arguments are reported with a warning, and nothing is displayed.

Omitted arguments produce an error.

<?php

// not enough
printf(' a %s ', $a1);
// OK
printf(' a %s ', $a1, $a2);
// too many
printf(' a %s ', $a1, $a2, $a3);

// not enough
sprintf(' a %s ', $a1);
// OK
\sprintf(' a %s ', $a1, $a2);
// too many
sprintf(' a %s ', $a1, $a2, $a3);

?>

See also printf and sprintf.

Short name Structures/PrintfArguments
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples PhpIPAM

9.489. Processing Collector

When accumulating data in a variable, within a loop, it is slow to apply repeatedly a function to the variable.

The example below illustrate the problem : $collector is build with element from $array. $collector actually gets larger and larger, slowing the in_array() call each time.

It is better to apply the preg_replace() to $a, a short variable, and then, add $a to the collector.

<?php

// Fast way
$collector = '';
foreach($array as $a){
    $a = preg_replace('/__(.*?)__/', '<b>$1</b>', $a);
    $collector .= $a;
}

// Slow way
$collector = '';
foreach($array as $a){
    $collector .= $a;
    $collector = preg_replace('/__(.*?)__/', '<b>$1</b>', $collector);
}

?>

9.489.1. Suggestions

  • Avoid applying the checks on the whole data, rather on the diff only.
Short name Performances/RegexOnCollector
Rulesets Performances
Severity Minor
Time To Fix Slow (1 hour)

9.490. Property Could Be Local

A property only used in one method may be turned into a local variable.

Public an protected properties are omitted here : they may be modified somewhere else, in the code. This analysis may be upgraded to support those properties, when tracking of such properties becomes available.

Classes where only one non-magic method is available are omitted.

Traits with private properties are processed the same way.

<?php

class x {
    private $foo = 1;

    // Magic method, and constructor in particular, are omitted.
    function __construct($foo) {
        $this->foo = $foo;
    }

    function bar() {
        $this->foo++;

        return $this->foo;
    }

    function barbar() {}
}

?>

9.490.1. Suggestions

  • Remove the property and make it an argument in the method
  • Use that property elsewhere
Short name Classes/PropertyCouldBeLocal
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Slow (1 hour)
Examples Mautic, Typo3

9.491. Property Could Be Private Property

The following properties are never used outside their class of definition Given the analyzed code, they could be set as private.

<?php

class foo {
    public $couldBePrivate = 1;
    public $cantdBePrivate = 1;

    function bar() {
        // couldBePrivate is used internally.
        $this->couldBePrivate = 3;
    }
}

class foo2 extends foo {
    function bar2() {
        // cantdBePrivate is used in a child class.
        $this->cantdBePrivate = 3;
    }
}

//$couldBePrivate is not used outside
$foo = new foo();

//$cantdBePrivate is used outside the class
$foo->cantdBePrivate = 2;

?>

Note that dynamic properties (such as $x->$y) are not taken into account.

9.491.1. Suggestions

  • Remove the unused property
  • Use the private property
  • Change the visibility to allow access the property from other part of the code
Short name Classes/CouldBePrivate
Rulesets ClassReview
Severity Minor
Time To Fix Slow (1 hour)

9.492. Property Used In One Method Only

Properties should be used in several methods. When a property is used in only one method, this should have be of another shape.

Properties used in one method only may be used several times, and read only. This may be a class constant. Such properties are meant to be overwritten by an extending class, and that’s possible with class constants.

Properties that read and written may be converted into a variable, static to the method. This way, they are kept close to the method, and do not pollute the object’s properties.

<?php

class foo {
    private $once = 1;
    const ONCE = 1;
    private $counter = 0;

    function bar() {
        // $this->once is never used anywhere else.
        someFunction($this->once);
        someFunction(self::ONCE);   // Make clear that it is a
    }

    function bar2() {
        static $localCounter = 0;
        $this->counter++;

        // $this->once is only used here, for distinguising calls to someFunction2
        if ($this->counter > 10) { // $this->counter is used only in bar2, but it may be used several times
            return false;
        }
        someFunction2($this->counter);

        // $localCounter keeps track for all the calls
        if ($localCounter > 10) {
            return false;
        }
        someFunction2($localCounter);
    }
}

?>

Note : properties used only once are not returned by this analysis. They are omitted, and are available in the analysis Used Once Property.

9.492.1. Suggestions

  • Drop the property, and inline the value
  • Drop the property, and make the property a local variable
  • Use the property in another method
Short name Classes/PropertyUsedInOneMethodOnly
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples Contao

9.493. Property Variable Confusion

Within a class, there is both a property and variables bearing the same name.

<?php
class Object {
    private $x;

    function SetData( ) {
        $this->x = $x + 2;
    }
}
?>

The property and the variable may easily be confused one for another and lead to a bug.

Sometimes, when the property is going to be replaced by the incoming argument, or data based on that argument, this naming schema is made on purpose, indicating that the current argument will eventually end up in the property. When the argument has the same name as the property, no warning is reported.

9.493.1. Suggestions

  • Use different names for the properties and variables
  • Adopt and apply a naming convention for variables and properties.
Short name Structures/PropertyVariableConfusion
Rulesets Semantics
Severity Minor
Time To Fix Slow (1 hour)
Examples PhpIPAM

9.494. Queries In Loops

Avoid querying databases in a loop.

Querying an external database in a loop usually leads to performances problems. This is also called the ‘n + 1 problem’.

This problem applies also to prepared statement : when such statement are called in a loop, they are slower than one-time large queries.

It is recommended to reduce the number of queries by making one query, and dispatching the results afterwards. This is true with SQL databases, graph queries, LDAP queries, etc.

<?php

// Typical N = 1 problem : there will be as many queries as there are elements in $array
$ids = array(1,2,3,5,6,10);

$db = new SQLite3('mysqlitedb.db');

// all the IDS are merged into the query at once
$results = $db->query('SELECT bar FROM foo WHERE id  in ('.implode(',', $id).')');
while ($row = $results->fetchArray()) {
    var_dump($row);
}


// Typical N = 1 problem : there will be as many queries as there are elements in $array
$ids = array(1,2,3,5,6,10);

$db = new SQLite3('mysqlitedb.db');

foreach($ids as $id) {
    $results = $db->query('SELECT bar FROM foo WHERE id = '.$id);
    while ($row = $results->fetchArray()) {
        var_dump($row);
    }
}

?>

This optimisation is not always possible : for example, some SQL queries may not be prepared, like DROP TABLE or DESC. UPDATE commands often update one row at a time, and grouping such queries may be counter-productive or unsafe.

9.494.1. Suggestions

  • Batch calls by using WHERE clauses and applying the same operation to all similar data
  • Use native commands to avoid double query : REPLACE instead of SELECT-(UPDATE/INSERT), or UPSERT, for example
Short name Structures/QueriesInLoop
Rulesets Analyze, Top10
Severity Major
Time To Fix Slow (1 hour)
Examples TeamPass, OpenEMR

9.495. Raised Access Level

A property’s visibility may be lowered, but not raised.

This error may be detected when the classes are all in the same file : then, PHP reports the problem. However, when the classes are separated in different files, as it is customary, PHP won’t check this at linting time, yielding a fatal error at execution time.

First file.

<?php

class Foo {
    public $publicProperty;
    protected $protectedProperty;
    private $privateProperty;
}
?>

Second file.

<?php

class Bar extends Foo {
    private $publicProperty;
    private $protectedProperty;
    private $privateProperty;   // This one is OK
}
?>

See also Visibility and Understanding the concept of visibility in object oriented php.

9.495.1. Suggestions

  • Lower the visibility in the child class
  • Raise the visibility in the parent class
Short name Classes/RaisedAccessLevel
Rulesets ClassReview, LintButWontExec
Severity Critical
Time To Fix Quick (30 mins)

9.496. Random Without Try

random_int() and random_bytes() require a try/catch structure around them.

random_int() and random_bytes() emit Exceptions if they meet a problem. This way, failure can’t be mistaken with returning an empty value, which leads to lower security.

<?php

try {
    $salt = random_bytes($length);
} catch (TypeError $e) {
    // Error while reading the provided parameter
} catch (Exception $e) {
    // Insufficient random data generated
} catch (Error $e) {
    // Error with the provided parameter : <= 0
}

?>

Since PHP 7.4, openssl_random_pseudo_bytes() has adopted the same behavior. It is included in this analysis : check your PHP version for actual application.

9.496.1. Suggestions

  • Add a try/catch structure around calls to random_int() and random_bytes().
Short name Structures/RandomWithoutTry
Rulesets Security
Php Version With PHP 7.0 and more recent
Severity Critical
Time To Fix Quick (30 mins)

9.497. Randomly Sorted Arrays

Those literal arrays are written in several places, but their items are in various orders.

This may reduce the reading and proofing of the arrays, and induce confusion. The random order may also be a residue of development : both arrays started with different values, but they grew overtime to handle the same items. The way they were written lead to the current order.

Unless order is important, it is recommended to always use the same order when defining literal arrays. This makes it easier to match different part of the code by recognizing one of its literal.

<?php

// an array
$set = [1,3,5,9,10];

function foo() {
    // an array, with the same values but different order, in a different context
    $list = [1,3,5,10,9,];
}

// an array, with the same order than the initial one
$inits = [1,3,5,9,10];

?>

9.497.1. Suggestions

  • Match the sorting order of the arrays. Choose any of them.
  • Configure a constant and use it as a replacement for those arrays.
  • Leave the arrays intact : the order may be important.
  • For hash arrays, consider turning the array in a class.
Short name Arrays/RandomlySortedLiterals
Rulesets Analyze, Suggestions
Severity Minor
Time To Fix Slow (1 hour)
Examples Contao, Vanilla

9.498. Redeclared PHP Functions

Function that bear the same name as a PHP function, and that are declared.

This is useful when managing backward compatibility, like emulating an old function, or preparing for newer PHP versions, like emulating new upcoming function.

<?php

if (version_compare(PHP_VERSION, 7.0) > 0) {
    function split($separator, $string) {
        return explode($separator, $string);
    }
}

print_r( split(' ', '2 3'));

?>

9.498.1. Suggestions

  • Check if it is still worth emulating that function
Short name Functions/RedeclaredPhpFunction
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Slow (1 hour)

9.499. Redefined Class Constants

Redefined class constants.

Class constants may be redefined, though it is prone to errors when using them, as it is now crucial to use the right class name to access the right value.

<?php

class a {
    const A = 1;
}

class b extends a {
    const A = 2;
}

class c extends c { }

echo a::A, ' ', b::A, ' ', c::A;
// 1 2 2

?>

It is recommended to use distinct names.

Short name Classes/RedefinedConstants
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Slow (1 hour)

9.500. Redefined Default

Classes allows properties to be set with a default value. When those properties get, unconditionally, another value at constructor time, then one of the default value are useless. One of those definition should go : it is better to define properties outside the constructor.

<?php

class foo {
    public $redefined = 1;

    public function __construct( ) {
        $this->redefined = 2;
    }
}

?>

9.500.1. Suggestions

  • Move the default assignation to the property definition
  • Drop the reassignation in the constructor
Short name Classes/RedefinedDefault
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Slow (1 hour)
Examples Piwigo

9.501. Redefined Private Property

Private properties are local to their defined class. PHP doesn’t forbid the re-declaration of a private property in a child class.

However, having two or more properties with the same name, in the class hierarchy tends to be error prone.

<?php

class A {
    private $isReady = true;
}

class B {
    private $isReady = false;
}

?>
Short name Classes/RedefinedPrivateProperty
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)
Examples Zurmo

9.502. Redefined Property

Property redefined in a parent class.

Using heritage, it is possible to define several times the same property, at different levels of the hierarchy.

<?php

class foo {
    protected $aProperty = 1;
}

class bar extends foo {
    // This property is redefined in the parent class, leading to potential confusion
    protected $aProperty = 1;
}

?>

When this is the case, it is difficult to understand which class will actually handle the property.

In the case of a private property, the different instances will stay distinct. In the case of protected or public properties, they will all share the same value.

It is recommended to avoid redefining the same property in a hierarchy.

Short name Classes/RedefinedProperty
Rulesets ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.503. Reflection Export() Is Deprecated

export() method in Reflection classes is now deprecated. It is obsolete since PHP 7.4 and will disappear in PHP 8.0.

The Reflector interface, which is implemented by all reflection classes, specifies two methods: __toString() and export().

<?php

ReflectionFunction::export('foo');
// same as
echo new ReflectionFunction('foo'), \n;

$str = ReflectionFunction::export('foo', true);
// same as
$str = (string) new ReflectionFunction('foo');

?>

See also Reflection export() methods and Reflection.

9.503.1. Suggestions

  • Cast the object to string
  • Remove the call to export()
Short name Php/ReflectionExportIsDeprecated
Rulesets CompatibilityPHP74
Severity Minor
Time To Fix Quick (30 mins)

9.504. Regex On Arrays

Avoid using a loop with arrays of regex or values. There are several PHP function which work directly on arrays, and much faster.

preg_grep() is able to extract all matching strings from an array, or non-matching strings. This usually saves a loop over the strings.

preg_filter() is able to extract all strings from an array, matching at least one regex in an array. This usually saves a double loop over the strings and the regex. The trick here is to provide ‘$0’ as replacement, leading preg_filter() to replace the found string by itself.

Finally, preg_replace_callback() an preg_replace_callback_array() are also able to apply an array of regex to an array of strings, and then, apply callbacks to the found values.

<?php

$regexs = ['/ab+c/', '/abd+/', '/abe+/'];
$strings = ['/abbbbc/', '/abd/', '/abeee/'];

// Directly extract all strings that match one regex
foreach($regexs as $regex) {
    $results[] = preg_grep($regex, $strings);
}

// extract all matching regex, by string
foreach($strings as $string) {
    $results[] = preg_filter($regexs, array_fill(0, count($regexs), '$0'), $string);
}

// very slow way to get all the strings that match a regex
foreach($regexs as $regex) {
    foreach($strings as $string) {
        if (preg_match($regex, $string)) {
            $results[] = $string;
        }
    }
}

?>

See also preg_filter.

9.504.1. Suggestions

  • Apply preg_match() to an array of string or regex, via preg_filter() or preg_grep().
  • Apply preg_match() to an array of string or regex, via preg_replace_callback() or preg_replace_callback_array().
Short name Performances/RegexOnArrays
Rulesets Performances
Severity Minor
Time To Fix Quick (30 mins)

9.505. Register Globals

register_globals was a PHP directive that dumped all incoming variables from GET, POST, COOKIE and FILES as global variables in the called scripts. This lead to security failures, as the variables were often used but not filtered.

Though it is less often found in more recent code, register_globals is sometimes needed in legacy code, that haven’t made the move to eradicate this style of coding. Backward compatible pieces of code that mimic the register_globals features usually create even greater security risks by being run after scripts startup. At that point, some important variables are already set, and may be overwritten by the incoming call, creating confusion in the script.

Mimicking register_globals is achieved with variables variables, extract(), parse_str() and import_request_variables() (Up to PHP 5.4).

<?php

// Security warning ! This overwrites existing variables.
extract($_POST);

// Security warning ! This overwrites existing variables.
foreach($_REQUEST as $var => $value) {
    $$var = $value;
}

?>

9.505.1. Suggestions

  • Avoid reimplementing register_globals
  • Use a container to store and access commonly used values
Short name Security/RegisterGlobals
Rulesets Security
Severity Critical
Time To Fix Slow (1 hour)
Examples TeamPass, XOOPS

9.506. Relay Function

Relay function only delegate workload to another one.

Relay functions and methods are delegating the actual work to another function or method. They do not have any impact on the results, besides exposing another name for the same feature.

<?php

function myStrtolower($string) {
    return \strtolower($string);
}

?>

Relay functions are typical of transition API, where an old API have to be preserved until it is fully migrated. Then, they may be removed, so as to reduce confusion, and simplify the API.

9.506.1. Suggestions

  • Remove relay function, call directly the final function
  • Remove the target function, and move the code here
  • Add more logic to that function, like conditions or cache
Short name Functions/RelayFunction
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)
Examples TeamPass, SPIP

9.507. Repeated Interface

A class should implements only once an interface. An interface can only extends once another interface. In both cases, parent classes or interfaces must be checked.

PHP accepts multiple times the same interface in the implements clause. In fact, it doesn’t do anything beyond the first implement.

<?php

use i as j;

interface i {}

// Multiple ways to reference an interface
class foo implements i, \i, j {}

// This applies to interfaces too
interface bar extends i, \i, j {}

?>

This code may compile, but won’t execute.

See also Object Interfaces and The Basics.

9.507.1. Suggestions

  • Remove the interface usage at the lowest class or interface
Short name Interfaces/RepeatedInterface
Rulesets Analyze, LintButWontExec
Severity Minor
Time To Fix Instant (5 mins)

9.508. Repeated Regex

Repeated regex should be centralized.

When a regex is repeatedly used in the code, it is getting harder to update.

<?php

// Regex used several times, at least twice.
preg_match('/^abc_|^square$/i', $_GET['x']);

//.......

preg_match('/^abc_|^square$/i', $row['name']);

// This regex is dynamically built, so it is not reported.
preg_match('/^circle|^'.$x.'$/i', $string);

// This regex is used once, so it is not reported.
preg_match('/^circle|^square$/i', $string);

?>

Regex that are repeated at least once (aka, used twice or more) are reported. Regex that are dynamically build are not reported.

9.508.1. Suggestions

  • Create a central library of regex
  • Use the regex inventory to spot other regex that are close, and should be identical.
Short name Structures/RepeatedRegex
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples Vanilla, Tikiwiki

9.509. Repeated print()

Always merge several print or echo in one call.

It is recommended to use echo with multiple arguments, or a concatenation with print, instead of multiple calls to print echo, when outputting several blob of text.

<?php

//Write :
  echo 'a', $b, 'c';
  print 'a' . $b . 'c';

//Don't write :
  print 'a';
  print $b;
  print 'c';
?>

9.509.1. Suggestions

  • Merge all prints into one echo call, separating arguments by commas.
  • Collect all values in one variable, and do only one call to print or echo.
Short name Structures/RepeatedPrint
Rulesets Analyze, Suggestions, Top10, CI-checks
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-repeated-print
Examples Edusoho, HuMo-Gen

9.510. Reserved Keywords In PHP 7

PHP reserved names for class/trait/interface. They won’t be available anymore in user space starting with PHP 7.

For example, string, float, false, true, null, resource,`… <https://www.php.net/manual/en/functions.arguments.php#functions.variable-arg-list>`_ are not acceptable as class name.

<?php

// This doesn't compile in PHP 7.0 and more recent
class null { }

?>

See also List of other reserved words.

9.510.1. Suggestions

  • Avoid using PHP reserved keywords
Short name Php/ReservedKeywords7
Rulesets CompatibilityPHP70
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Slow (1 hour)

9.511. Results May Be Missing

preg_match() may return empty values, if the search fails. It is important to check for the existence of results before assigning them to another variable, or using it.

<?php
    preg_match('/PHP ([0-9\.]+) /', $res, $r);
    $s = $r[1];
    // $s may end up null if preg_match fails.
?>
Short name Structures/ResultMayBeMissing
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)

9.512. Rethrown Exceptions

Throwing a caught exception is usually useless and dead code.

When exceptions are caught, they should be processed or transformed, but not rethrown as is.

Those issues often happen when a catch structure was positioned for debug purposes, but lost its usage later.

<?php

try {
    doSomething();
} catch (Exception $e) {
    throw $e;
}

?>

See also What are the best practices for catching and re-throwing exceptions? and Exception chaining.

9.512.1. Suggestions

  • Log the message of the exception for later usage.
  • Remove the try/catch and let the rest of the application handle this exception.
  • Chain the exception, by throwing a new exception, including the caught exception.
Short name Exceptions/Rethrown
Rulesets Dead code
Severity Minor
Time To Fix Quick (30 mins)
Examples PrestaShop

9.513. Return True False

These conditional expressions return true/false, depending on the condition. This may be simplified by dropping the control structure altogether.

<?php

if (version_compare($a, $b) >= 0) {
    return true;
} else {
    return false;
}

?>

This may be simplified with :

<?php

return version_compare($a, $b) >= 0;

?>

This may be applied to assignations and ternary operators too.

<?php

if (version_compare($a, $b) >= 0) {
    $a = true;
} else {
    $a = false;
}

$a = version_compare($a, $b) >= 0 ? false : true;

?>

9.513.1. Suggestions

  • Return directly the comparison, without using the if/then structure
  • Cast the value to (boolean) and use it instead of the ternary
Short name Structures/ReturnTrueFalse
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples Mautic, FuelCMS

9.514. Return With Parenthesis

return statement doesn’t need parenthesis. PHP tolerates them with return statement, but it is recommended not to use them.

From the PHP Manual : ‘Note: Note that since return is a language construct and not a function, the parentheses surrounding its argument are not required and their use is discouraged.’.

<?php

function foo() {
    $a = rand(0, 10);

    // No need for parenthesis
    return $a;

    // Parenthesis are useless here
    return ($a);

    // Parenthesis are useful here: they are needed by the multplication.
    return ($a + 1) * 3;
}

?>

See also PHP return(value); vs return value; and return.

9.514.1. Suggestions

  • Remove the parenthesis
Short name Php/ReturnWithParenthesis
Rulesets Coding Conventions, Suggestions
Severity Minor
Time To Fix Instant (5 mins)

9.515. Reuse Variable

A variable is already holding the content that is calculated multiple times over.

It is recommended to use the cached value. This saves some computation, in particular when used in a loop, and speeds up the process.

<?php

function foo($a) {
    $b = strtolower($a);

    // strtolower($a) is already calculated in $b. Just reuse the value.
    if (strtolower($a) === 'c') {
        doSomething();
    }
}

?>

9.515.1. Suggestions

  • Reuse the already created variable
Short name Structures/ReuseVariable
Rulesets Suggestions
Severity Minor
Time To Fix Slow (1 hour)
Precision Medium

9.516. Safe Curl Options

It is advised to always use CURLOPT_SSL_VERIFYPEER and CURLOPT_SSL_VERIFYHOST when requesting a SSL connection.

With those tests, the certificate is verified, and if it isn’t valid, the connection fails : this is a safe behavior.

<?php
$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, https://www.php.net/);

// To be safe, always set this to true
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);

curl_exec($ch);
curl_close($ch);
?>

See also Don’t turn off CURLOPT_SSL_VERIFYPEER, fix your PHP configuration, Certainty: Automated CACert.pem Management for PHP Software and Server-Side HTTPS Requests.

9.516.1. Suggestions

  • Always use CURLOPT_SSL_VERIFYPEER and HTTPS for communication with other servers
Short name Security/CurlOptions
Rulesets Security
Severity Major
Time To Fix Quick (30 mins)
Examples OpenConf

9.517. Safe HTTP Headers

Avoid configuring HTTP headers with lax restriction from within PHP.

There are a lot of HTTP headers those days, targeting various vulnerabilities. To ensure backward compatibility, those headers have a default mode that is lax and permissive. It is recommended to avoid using those from within the code.

<?php

//Good configuration, limiting access to origin
header('Access-Control-Allow-Origin: https://www.exakat.io');

//Configuration is present, but doesn't restrict anything : any external site is a potential source
header('Access-Control-Allow-Origin: *');

?>

See also Hardening Your HTTP Security Headers, How To Secure Your Web App With HTTP Headers and SecurityHeaders.

9.517.1. Suggestions

  • Remove usage of those headers
Short name Security/SafeHttpHeaders
Rulesets Security
Severity Major
Time To Fix Quick (30 mins)

9.518. Same Conditions In Condition

At least two consecutive if/then structures use identical conditions. The latter will probably be ignored.

This analysis returns false positive when there are attempt to fix a situation, or to call an alternative solution.

Conditions that are shared between if structures, but inside a logical OR expression are also detected.

<?php

if ($a == 1) { doSomething(); }
elseif ($b == 1) { doSomething(); }
elseif ($c == 1) { doSomething(); }
elseif ($a == 1) { doSomething(); }
else {}

// Also works on if then else if chains
if ($a == 1) { doSomething(); }
else if ($b == 1) { doSomething(); }
else if ($c == 1) { doSomething(); }
else if ($a == 1) { doSomething(); }
else {}

// Also works on if then else if chains
// Here, $a is common and sufficient in both conditions
if ($a || $b) { doSomething(); }
elseif ($a || $c) { doSomethingElse(); }

// This sort of situation generate false postive.
$config = load_config_from_commandline();
if (empty($config)) {
    $config = load_config_from_file();
    if (empty($config)) {
        $config = load_default_config();
    }
}

?>

9.518.1. Suggestions

  • Merge the two conditions into one
  • Make the two conditions different
Short name Structures/SameConditions
Rulesets Analyze, CI-checks
Severity Critical
Time To Fix Quick (30 mins)
Examples TeamPass, Typo3

9.519. Same Variable Foreach

A foreach which uses its own source as a blind variable is actually broken.

Actually, PHP makes a copy of the source before it starts the loop. As such, the same variable may be used for both source and blind value.

Of course, this is very confusing, to see the same variables used in very different ways.

The source will also be destroyed immediately after the blind variable has been turned into a reference.

<?php

$array = range(0, 10);
foreach($array as $array) {
    print $array.PHP_EOL;
}

print_r($array); // display number from 0 to 10.

$array = range(0, 10);
foreach($array as &$array) {
    print $array.PHP_EOL;
}

print_r($array); // display 10

?>
Short name Structures/AutoUnsetForeach
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.520. Scalar Are Not Arrays

It is wrong to use a scalar as an array, a Warning is emitted. PHP 7.4 emits a Warning in such situations.

<?php

// Here, $x may be null, and in that case, the echo will fail.
function foo(?A $x) {
    echo $x[2];
}

?>

Typehinted argument with a scalar are reported by this analysis. Also, nullable arguments, both with typehint and return type hint.

See also E_WARNING for invalid container read array-access.

9.520.1. Suggestions

  • Update type hints to avoid scalar values
  • Remove the array syntax in the code using the results
Short name Php/ScalarAreNotArrays
Rulesets Analyze, CompatibilityPHP74, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Precision High

9.521. Scalar Or Object Property

Property shouldn’t use both object and scalar syntaxes. When a property may be an object, it is recommended to implement the Null Object pattern : instead of checking if the property is scalar, make it always object.

<?php

class x {
    public $display = 'echo';

    function foo($string) {
        if (is_string($this->display)) {
            echo $this->string;
        } elseif ($this->display instanceof myDisplayInterface) {
            $display->display();
        } else {
            print Error when displaying\n;
        }
    }
}

interface myDisplayInterface {
    public function display($string); // does the display in its own way
}

class nullDisplay implements myDisplayInterface {
    // implements myDisplayInterface but does nothing
    public function display($string) {}
}

class x2 {
    public $display = null;

    public function __construct() {
        $this->display = new nullDisplay();
    }

    function foo($string) {
        // Keep the check, as $display is public, and may get wrong values
        if ($this->display instanceof myDisplayInterface) {
            $display->display();
        } else {
            print Error when displaying\n;
        }
    }
}

// Simple class for echo
class echoDisplay implements myDisplayInterface {
    // implements myDisplayInterface but does nothing
    public function display($string) {
        echo $string;
    }
}

?>

See also Null Object Pattern. and The Null Object Pattern.

9.521.1. Suggestions

  • Only use one type of syntax with your properties.
Short name Classes/ScalarOrObjectProperty
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples SugarCrm

9.522. Self Using Trait

Trait uses itself : this is unnecessary. Traits may use themselves, or be used by other traits, that are using the initial trait itself.

PHP handles the situation quietly, by ignoring all extra use of the same trait, keeping only one valid version.

<?php

// empty, but valid
trait a {}

// obvious self usage
trait b { use b; }

// less obvious self usage
trait c { use d, e, f, g, h, c; }

// level 2 self usage
trait i { use j; }
trait j { use i; }

?>

See also Traits.

9.522.1. Suggestions

  • Remove the extra usage of the trait.
Short name Traits/SelfUsingTrait
Rulesets Dead code, ClassReview
Severity Minor
Time To Fix Slow (1 hour)

9.523. Semantic Typing

Arguments names are only useful inside the method’s body. They are not actual type.

<?php

// arguments should be a string and an array
function foo($array, $str) {
    // more code
    return $boolean;
}

// typehint is actually checking the values
function bar(iterable $closure) : bool {
    // more code
    return true;
}

?>

9.523.1. Suggestions

  • Use a typehint to make sure the argument is of the expected type.
Short name Functions/SemanticTyping
Rulesets Semantics
Severity Minor
Time To Fix Quick (30 mins)

9.524. Session Lazy Write

Classes that implements SessionHandlerInterface must also implements SessionUpdateTimestampHandlerInterface.

The two extra methods are used to help lazy loading : the first actually checks if a sessionId is available, and the seconds updates the time of last usage of the session data in the session storage.

This was spotted by Nicolas Grekas, and fixed in Symfony [HttpFoundation] Make sessions secure and lazy #24523.

<?php

interface SessionUpdateTimestampHandlerInterface {
    // returns a boolean to indicate that valid data is available for this sessionId, or not.
    function validateId($sessionId);

    //called to change the last time of usage for the session data.
    //It may be a file's touch or full write, or a simple update on the database
    function updateTimestamp($sessionId, $sessionData);
}

?>

See also Sessions: Improve original RFC about lazy_write and the Sessions.

9.524.1. Suggestions

  • Implements the SessionUpdateTimestampHandlerInterface interface
Short name Security/SessionLazyWrite
Rulesets Security
Severity Major
Time To Fix Slow (1 hour)

9.525. Set Aside Code

Setting aside code should be made into a method.

Setting aside code happens when one variable or member is stored locally, to be temporarily replaced by another value. Once the new value has been processed, the original value is reverted.

The temporary change of the value makes the code hard to read.

It is a good example of a piece of code that could be moved to a separate method or function. Using the temporary value as a parameter makes the change visible, and avoid local pollution.

<?php

// Setting aside database
class cache extends Storage {
    private $database = null;

    function __construct($database) {
        $this->database = $database;
    }

    function foo($values) {
        // handling storage with sqlite3
        $secondary = new cache(new Sqlite3(':memory:'));
        $secondary->store($values);

        $this->store($values);      // handling storage with injection
    }
}

// Setting aside database to cache data in two distinct backend
class cache extends Storage {
    private $database = null;

    function __construct(\Pdo $database) {
        $this->database = $database;
    }

    function foo($values) {
        // $this->database is set aside for secondary configuration
        $side = $this->database;
        $this->database = new Sqlite3(':memory:');
        $this->store($values);      // handling storage with sqlite3
        $this->database = $side;
        // $this->database is restored
        $this->store($values);      // handling storage with injection
    }
}

?>

9.525.1. Suggestions

  • Extract the code that run with the temporary value to a separate method.
Short name Structures/SetAside
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.527. Setlocale() Uses Constants

setlocal() don’t use strings but constants.

The first argument of setlocale() must be one of the valid constants, LC_ALL, LC_COLLATE, LC_CTYPE, LC_MONETARY, LC_NUMERIC, LC_TIME, LC_MESSAGES.

<?php

// Use constantes for setlocale first argument
setlocale(LC_ALL, 'nl_NL');
setlocale(\LC_ALL, 'nl_NL');

// Don't use string for setlocale first argument
setlocale('LC_ALL', 'nl_NL');
setlocale('LC_'.'ALL', 'nl_NL');

?>

The PHP 5 usage of strings (same name as above, enclosed in ‘ or “) is not legit anymore in PHP 7 and later.

See also setlocale.

Short name Structures/SetlocaleNeedsConstants
Rulesets CompatibilityPHP70
Severity Major
Time To Fix Instant (5 mins)

9.528. Several Instructions On The Same Line

Usually, instructions do not share their line : one instruction, one line.

This is good for readability, and help at understanding the code. This is especially important when fast-reading the code to find some special situation, where such double-meaning line way have an impact.

<?php

switch ($x) {
    // Is it a fallthrough or not ?
    case 1:
        doSomething(); break;

    // Easily spotted break.
    case 1:
        doSomethingElse();
        break;

    default :
        doDefault();
        break;
}

?>

See also Object Calisthenics, rule # 5.

Short name Structures/OneLineTwoInstructions
Rulesets Analyze
Severity Major
Time To Fix Instant (5 mins)
Examples Piwigo, Tine20

9.529. Short Open Tags

Usage of short open tags is discouraged. The following files were found to be impacted by the short open tag directive at compilation time. They must be reviewed to ensure no &lt;? tags are found in the code.

Short name Php/ShortOpenTagRequired
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.530. Short Syntax For Arrays

Arrays written with the new short syntax.

PHP 5.4 introduced the new short syntax, with square brackets. The previous syntax, based on the array() keyword is still available.

<?php

// All PHP versions array
$a = array(1, 2, 3);

// PHP 5.4+ arrays
$a = [1, 2, 3];

?>

See also Array.

Short name Arrays/ArrayNSUsage
Rulesets CompatibilityPHP53
Severity Critical
Time To Fix Quick (30 mins)

9.531. Should Be Single Quote

Use single quote for simple strings.

Static content inside a string, that has no single quotes nor escape sequence (such as n or t), should be using single quote delimiter, instead of double quote.

<?php

$a = abc;

// This one is using a special sequence
$b = cde\n;

// This one is using two special sequences
$b = \x03\u{1F418};

?>

If you have too many of them, don’t loose your time switching them all. If you have a few of them, it may be good for consistence.

Short name Type/ShouldBeSingleQuote
Rulesets Coding Conventions
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP no-double-quote

9.532. Should Chain Exception

Chain exception to provide more context.

When catching an exception and rethrowing another one, it is recommended to chain the exception : this means providing the original exception, so that the final recipient has a chance to track the origin of the problem. This doesn’t change the thrown message, but provides more information.

Note : Chaining requires PHP > 5.3.0.

<?php
    try {
        throw new Exception('Exception 1', 1);
    } catch (\Exception $e) {
        throw new Exception('Exception 2', 2, $e);
        // Chaining here.

    }
?>

See also Exception::`__construct <https://www.php.net/manual/en/exception.construct.php>`_ and What are the best practices for catching and re-throwing exceptions?.

9.532.1. Suggestions

  • Add the incoming exception to the newly thrown exception
Short name Structures/ShouldChainException
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples Magento, Tine20

9.533. Should Deep Clone

By default, PHP makes a shallow clone. It only clone the scalars, and keep the reference to any object already referenced. This means that the cloned object and its original share any object they hold as property.

This is where the magic method __clone() comes into play. It is called, when defined, at clone time, so that the cloned object may clone all the needed sub-objects.

It is recommended to use the __clone() method whenever the objects hold objects.

<?php

class a {
    public $b = null;

    function __construct() {
        $this->b =  new Stdclass();
        $this->b->c = 1;
    }
}

class ab extends a {
    function __clone() {
        $this->b = clone $this->b;
    }
}

// class A is shallow clone, so $a->b is not cloned
$a = new a();
$b = clone $a;
$a->b->c = 3;
echo $b->b->c;
// displays 3

// class Ab is deep clone, so $a->b is cloned
$a = new ab();
$b = clone $a;
$a->b->c = 3;
echo $b->b->c;
// displays 1

?>

See also PHP Clone and Shallow vs Deep Copying and Cloning objects.

9.533.1. Suggestions

Short name Classes/ShouldDeepClone
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.534. Should Have Destructor

PHP destructors are called when the object has to be destroyed. By default, PHP calls recursively the destructor on internal objects, until everything is unset.

Unsetting objects and resources explicitly in the destructor is a good practice to reduce the amount of memory in use. It helps PHP resource counter to keep the numbers low, and easier to clean. This is a major advantage for long running scripts.

<?php

class x {
    function __construct() {
        $this->p = new y();
    }

    function __destruct() {
        print __METHOD__.PHP_EOL;
        unset($this->p);
    }
}

class y {
    function __construct() {
        print __METHOD__.PHP_EOL;
        $this->p = new y();
    }

    function __destruct() {
        print __METHOD__.PHP_EOL;
        unset($this->p);
    }
}

$a = (new x);
sleep(1);

// This increment the resource counter by one for the property.
$p = $a->p;
unset($a);
sleep(3);

print 'end'.PHP_EOL;
// Y destructor is only called here, as the object still exists in $p.

?>

See also Destructor, and Php Destructors.

9.534.1. Suggestions

  • Add a destruct method to the class to help clean at destruction time.
Short name Classes/ShouldHaveDestructor
Rulesets Suggestions
Severity Minor
Time To Fix Slow (1 hour)

9.535. Should Make Alias

Long names should be aliased.

Aliased names are easy to read at the beginning of the script; they may be changed at one point, and update the whole code at the same time. Finally, short names makes the rest of the code readable.

<?php

namespace x\y\z;

use a\b\c\d\e\f\g as Object;

// long name, difficult to read, prone to change.
new a\b\c\d\e\f\g();

// long name, difficult to read, prone to silent dead code if namespace change.
if ($o instanceof a\b\c\d\e\f\g) {

}

// short names Easy to update all at once.
new Object();
if ($o instanceof Object) {

}

?>
Short name Namespaces/ShouldMakeAlias
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.536. Should Make Ternary

Ternary operators are the best when assigning values to a variable.

This way, they are less verbose, compatible with assignation and easier to read.

<?php
    // verbose if then structure
    if ($a == 3) {
        $b = 2;
    } else {
        $b = 3;
    }

    // compact ternary call
    $b = ($a == 3) ? 2 : 3;

    // verbose if then structure
    // Works with short assignations and simple expressions
    if ($a != 3) {
        $b += 2 - $a * 4;
    } else {
        $b += 3;
    }

    // compact ternary call
    $b += ($a != 3) ? 2 - $a * 4 : 3;

?>
Short name Structures/ShouldMakeTernary
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)

9.537. Should Preprocess Chr()

Replace literal chr() calls with their escape sequence.

chr() is a functioncall, that cannot be cached. It is only resolved at execution time. On the other hand, literal values are preprocessed by PHP and may be cached.

<?php

// This is easier on PHP
$a = "0000 is great!";

// This is slow
$a = chr(80), chr(72), chr(80), chr(32), ' is great!';

// This would be the best with this example, but it is not always possible
$a = 'PHP is great!';

?>

This is a micro-optimisation.

See also Escape sequences.

9.537.1. Suggestions

  • Use PHP string sequences, and skip chr() at execution time
Short name Php/ShouldPreprocess
Rulesets none
Examples phpadsnew

9.538. Should Typecast

When typecasting, it is better to use the casting operator, such as (int) or (bool).

Functions such as intval() or settype() are always slower.

<?php

// Fast version
$int = (int) $X;

// Slow version
$int = intval($X);

// Convert to base 8 : can't use (int) for that
$int = intval($X, 8);


?>

This is a micro-optimisation, although such conversion may be use multiple time, leading to a larger performance increase.

Note that intval() may also be used to convert an integer to another base.

9.538.1. Suggestions

  • Use a typecast, instead of a functioncall.
Short name Type/ShouldTypecast
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples xataface, OpenConf

9.539. Should Use Coalesce

PHP 7 introduced the ?? operator, that replaces longer structures to set default values when a variable is not set.

<?php

// Fetches the request parameter user and results in 'nobody' if it doesn't exist
$username = $_GET['user'] ?? 'nobody';
// equivalent to: $username = isset($_GET['user']) ? $_GET['user'] : 'nobody';

// Calls a hypothetical model-getting function, and uses the provided default if it fails
$model = Model::get($id) ?? $default_model;
// equivalent to: if (($model = Model::get($id)) === NULL) { $model = $default_model; }

?>

Sample extracted from PHP docs Isset Ternary.

See also New in PHP 7: null coalesce operator.

9.539.1. Suggestions

  • Replace the long syntax with the short one
Short name Php/ShouldUseCoalesce
Rulesets Analyze, Suggestions, CI-checks
Php Version With PHP 7.0 and more recent
Severity Major
Time To Fix Quick (30 mins)
Examples ChurchCRM, Cleverstyle

9.540. Should Use Constants

The following functions have related constants that should be used as arguments, instead of scalar literals, such as integers or strings.

<?php

// The file is read and new lines are ignored.
$lines = file('file.txt', FILE_IGNORE_NEW_LINES)

// What is this doing, with 2 ?
$lines = file('file.txt', 2);

?>

See also Bitmask Constant Arguments in PHP.

9.540.1. Suggestions

  • Use PHP native constants whenever possible, for better readability.
Short name Functions/ShouldUseConstants
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples Tine20

9.541. Should Use Explode Args

explode() has a third argument, which limits the amount of exploded elements. With it, it is possible to collect only the first elements, or drop the last ones.

<?php

$exploded = explode(DELIMITER, $string);

// use explode(DELIMITER, $string, -1);
array_pop($exploded);

// use explode(DELIMITER, $string, -2);
$c = array_slice($exploded, 0, -2);

// with explode()'s third argument :
list($a, $b) = explode(DELIMITER, $string, 2);

// with list() omitted arguments
list($a, $b, ) = explode(DELIMITER, $string);

?>

See also explode.

9.541.1. Suggestions

Short name Structures/ShouldUseExplodeArgs
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.542. Should Use Foreach

Use foreach instead of for when traversing an array.

Foreach() is the modern loop : it maps automatically every element of the array to a blind variable, and loop over it. This is faster and safer.

<?php

// Foreach version
foreach($array as $element) {
    doSomething($element);
}

// The above case may even be upgraded with array_map and a callback,
// for the simplest one of them
$array = array_map('doSomething', $array);

// For version (one of various alternatives)
for($i = 0; $i < count($array); $i++) {
    $element = $array[$i];
    doSomething($element);
}

// Based on array_pop or array_shift()
while($value = array_pop($array)) {
    doSomething($array);
}

?>

See also foreach and 5 Ways To Loop Through An Array In PHP.

9.542.1. Suggestions

  • Move for() loops to foreach(), whenever they apply to a finite list of elements
Short name Structures/ShouldUseForeach
Rulesets Suggestions
Severity Minor
Time To Fix Instant (5 mins)
Examples ExpressionEngine, Woocommerce

9.543. Should Use Function

Functioncalls that fall back to global scope should be using ‘use function’ or be fully namespaced.

PHP searches for functions in the local namespaces, and in case it fails, makes the same search in the global scope. Anytime a native function is referenced this way, the search (and fail) happens. This slows down the scripts.

The speed bump range from 2 to 8 %, depending on the availability of functions in the local scope. The overall bump is about 1 µs per functioncall, which makes it a micro optimisation until a lot of function calls are made.

Based on one of Marco Pivetta tweet.

<?php

namespace X {
    use function strtolower as strtolower_aliased;

    // PHP searches for strtolower in X, fails, then falls back to global scope, succeeds.
    $a = strtolower($b);

    // PHP searches for strtolower in global scope, succeeds.
    $a = \strtolower($b);

    // PHP searches for strtolower_aliased in global scope, succeeds.
    $a = \strtolower_aliased($b);
}

?>

This analysis is a related to Performances/Php74ArrayKeyExists, and is a more general version.

See also blog post.

9.543.1. Suggestions

  • Use the use command for arrray_key_exists(), at the beginning of the script
  • Use an initial before array_key_exists()
  • Remove the namespace
Short name Php/ShouldUseFunction
Rulesets Performances
Severity Minor
Time To Fix Slow (1 hour)

9.544. Should Use Local Class

Methods should use the defining class, or be functions.

Methods should use $this with another method or a property, or call parent\:\:. Static methods should call another static method, or a static property. Methods which are overwritten by a child class are omitted : the parent class act as a default value for the children class, and this is correct.

<?php

class foo {
    public function __construct() {
        // This method should do something locally, or be removed.
    }
}

class bar extends foo {
    private $a = 1;

    public function __construct() {
        // Calling parent:: is sufficient
        parent::__construct();
    }

    public function barbar() {
        // This is acting on the local object
        $this->a++;
    }

    public function barfoo($b) {
        // This has no action on the local object. It could be a function or a closure where needed
        return 3 + $b;
    }
}

?>

Note that a method using a class constant is not considered as using the local class, for this analyzer.

9.544.1. Suggestions

  • Make this method a function
  • Actually use $this, or any related attributes of the class
Short name Classes/ShouldUseThis
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
ClearPHP not-a-method

9.545. Should Use Math

Use math operators to make the operation readable.

<?php

// Adding one to self
$a *= 2;
// same as above
$a += $a;

// Squaring oneself
$a \*\*\= 2;
// same as above
$a *= $a;

// Removing oneself
$a = 0;
// same as above
$a -= $a;

// Dividing oneself
$a = 1;
// same as above
$a /= $a;

// Divisition remainer
$a = 0;
// same as above
$a %= $a;

?>

See also Mathematical Functions.

9.545.1. Suggestions

  • Use explicit math assignation
Short name Structures/ShouldUseMath
Rulesets Suggestions
Severity Minor
Time To Fix Instant (5 mins)
Examples OpenEMR

9.546. Should Use Operator

Some functions duplicate the feature of an operator. When in doubt, it is better to use the operator.

Beware, some edge cases may apply. In particular, backward compatibility may prevent usage of newer features.

  • array_push() is equivalent to []
  • is_object() is equivalent to instanceof
  • function_get_arg() and function_get_args() is equivalent to ellipsis :
  • chr() is equivalent to string escape sequences, such as \n, \x69, u{04699}
  • call_user_func() is equivalent to $functionName(arguments), $object->$method(`... <https://www.php.net/manual/en/functions.arguments.php#functions.variable-arg-list>`_$arguments)
  • is_null() is equivalent to === null
  • php_version() is equivalent to PHP_VERSION (the constant)
  • is_array(), is_int(), is_object(), etc. is equivalent to a scalar typehint

9.546.1. Suggestions

  • Use [] instead of array_push()
  • Use instanceof instead of is_object()
  • Use … instead of function_get_arg() and function_get_args()
  • Use escape sequences instead of chr()
  • Use dynamic function call instead of call_user_func()
  • Use === null instead of is_null()
  • Use PHP_VERSION instead of php_version()
  • Use typehint instead of is_int(), is_string(), is_bool(), etc.
Short name Structures/ShouldUseOperator
Rulesets Suggestions
Severity Minor
Time To Fix Instant (5 mins)
Examples Zencart, SugarCrm

9.547. Should Use Prepared Statement

Modern databases provides support for prepared statement : it separates the query from the processed data and raise significantly the security.

Building queries with concatenations is not recommended, though not always avoidable. When possible, use prepared statements.

<?php
/* Execute a prepared statement by passing an array of values */

$sql = 'SELECT name, colour, calories
    FROM fruit
    WHERE calories < :calories AND colour = :colour';
$sth = $conn->prepare($sql, array(PDO::ATTR_CURSOR => PDO::CURSOR_FWDONLY));
$sth->execute(array(':calories' => 150, ':colour' => 'red'));
$red = $sth->fetchAll();
?>

Same code, without preparation :

<?php

    $sql = 'SELECT name, color, calories FROM fruit WHERE calories < '.$conn-quote(150).' AND colour = '.$conn->quotes('red').' ORDER BY name';
    $sth = $conn->query($sql) as $row);
}
?>

See also Prepared Statements, PHP MySQLi Prepared Statements Tutorial to Prevent SQL Injection, The Best Way to Perform MYSQLI Prepared Statements in PHP.

9.547.1. Suggestions

  • Use an ORM
  • Use an Active Record library
  • Change the query to hard code it and make it not injectable
Name Default Type Description
queryMethod query_methods.json data Methods that call a query.
Short name Security/ShouldUsePreparedStatement
Rulesets Analyze, Security, CI-checks
Severity Major
Time To Fix Slow (1 hour)
Examples Dolibarr

9.548. Should Use SetCookie()

Use setcookie() or setrawcookie(). Avoid using header() to do so, as the PHP native functions are more convenient and easier to spot during a refactoring.

setcookie() applies some encoding internally, for the value of the cookie and the date of expiration. Rarely, this encoding has to be skipped : then, use setrawencoding().

Both functions help by giving a checklist of important attributes to be used with the cookie.

<?php

// same as below
setcookie(myCookie, 'chocolate', time()+3600, /, , true, true);

// same as above. Slots for path and domain are omitted, but should be used whenever possible
header('Set-Cookie: myCookie=chocolate; Expires='.date('r', (time()+3600)).'; Secure; HttpOnly');

?>

See also Set-Cookie, setcookie.

9.548.1. Suggestions

  • Use setcookie() function, instead of header()
  • Use setcookie() function, instead of header()
Short name Php/UseSetCookie
Rulesets Analyze
Severity Major
Time To Fix Instant (5 mins)

9.549. Should Use array_column()

Avoid writing a whole slow loop, and use the native array_column().

array_column() is a native PHP function, that extract a property or a index from a array of object, or a multidimensional array. This prevents the usage of foreach to collect those values.

<?php

$a = array(array('b' => 1),
           array('b' => 2, 'c' => 3),
           array(          'c' => 4)); // b doesn't always exists

$bColumn = array_column($a, 'b');

// Slow and cumbersome code
$bColumn = array();
foreach($a as $k => $v) {
    if (isset($v['b'])) {
        $bColumn[] = $v['b'];
    }
}

?>

array_column() is faster than foreach() (with or without the isset() test) with 3 elements or more, and it is significantly faster beyond 5 elements. Memory consumption is the same.

See also [blog] `array_column() <https://benramsey.com/projects/array-column/>`_.

9.549.1. Suggestions

  • Use array_column(), instead of a foreach()
Short name Php/ShouldUseArrayColumn
Rulesets Performances, Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.550. Should Use array_filter()

Should use array_filter().

array_filter() is a native PHP function, that extract elements from an array, based on a closure or a function. Using array_filter() shortens your code, and allows for reusing the filtering logic across the application, instead of hard coding it every time.

<?php

$a = range(0, 10); // integers from 0 to 10

// Extracts odd numbers
$odds = array_filter($a, function($x) { return $x % 2; });
$odds = array_filter($a, 'odd');

// Slow and cumbersome code for extracting odd numbers
$odds = array();
foreach($a as $v) {
    if ($a % 2) { // same filter than the closure above, or the odd function below
        $bColumn[] = $v;
    }
}

function foo($x) {
    return $x % 2;
}

?>

array_filter() is faster than foreach() (with or without the isset() test) with 3 elements or more, and it is significantly faster beyond 5 elements. Memory consumption is the same.

See also array_filter.

9.550.1. Suggestions

  • Use array_filter()
Short name Php/ShouldUseArrayFilter
Rulesets Suggestions
Severity Minor
Time To Fix Slow (1 hour)
Examples xataface, shopware

9.551. Should Use session_regenerateid()

session_regenerateid() should be used when sessions are used.

When using sessions, a session ID is assigned to the user. It is a random number, used to connect the user and its data on the server. Actually, anyone with the session ID may have access to the data. This is why those session ID are so long and complex.

A good approach to protect the session ID is to reduce its lifespan : the shorter the time of use, the better. While changing the session ID at every hit on the page may no be possible, a more reasonable approach is to change the session id when an important action is about to take place. What important means is left to the application to decide.

Based on this philosophy, a code source that uses ZendSession but never uses ZendSession::regenerateId() has to be updated.

<?php

    session_start();

    $id = (int) $_SESSION['id'];
    // no usage of session_regenerateid() anywhere triggers the analysis

    // basic regeneration every 20 hits on the page.
    if (++$_SESSION['count'] > 20) {
        session_regenerateid();
    }

?>

See session_regenerateid() and PHP Security Guide: Sessions.

9.551.1. Suggestions

  • Add session_regenerateid() call before any important operation on the application
Short name Security/ShouldUseSessionRegenerateId
Rulesets Security
Severity Major
Time To Fix Slow (1 hour)

9.552. Should Yield With Key

iterator_to_array() will overwrite generated values with the same key.

PHP generators are based on the yield keyword. They also delegate some generating to other methods, with yield from.

When delegating, yield from uses the keys that are generated with yield, and otherwise, it uses auto-generated index, starting with 0.

The trap is that each yield from reset the index generation and start again with 0. Coupled with iterator_to_array(), this means that the final generated array may lack some values, while a foreach() loop would yield all of them.

<?php

function g1() : Generator {
     for ( $i = 0; $i < 4; $i++ ) { yield $i; }
}

function g2() : Generator {
     for ( $i = 5; $i < 10; $i++ ) { yield $i; }
}

function aggregator() : Generator {
     yield from g1();
     yield from g2();
}

print_r(iterator_to_array());

/*
Array
(
    [0] => 6
    [1] => 7
    [2] => 8
    [3] => 9
    [4] => 4  // Note that 4 and 5 still appears
    [5] => 5  // They are not overwritten by the second yield
)
*/


foreach ( aggregator() as $i ) {
     print $i.PHP_EOL;
}

/*
0  // Foreach has no overlap and yield it all.
1
2
3
4
5
6
7
8
9
*/

?>

Thanks to Holger Woltersdorf for pointing this.

See also Generator syntax and Yielding values with keys.

9.552.1. Suggestions

  • Use iterator_to_array() on each generator separately, and use array_merge() to merge all the arrays.
  • Always yield with distinct keys
  • Avoid iterator_to_array() and use foreach()
Short name Functions/ShouldYieldWithKey
Rulesets Analyze, Top10, CI-checks
Severity Major
Time To Fix Slow (1 hour)

9.553. Signature Trailing Comma

Trailing comma in method signature. This feature was added in PHP 8.0.

Allowing the trailing comma makes it possible to reduce the size of VCS’s diff, when adding , removing a parameter.

<?php

// Example from the RFC
class Uri {
    private function __construct(
        ?string $scheme,
        ?string $user,
        ?string $pass,
        ?string $host,
        ?int $port,
        string $path,
        ?string $query,
        ?string $fragment // <-- ARGH!
    ) {
        ...
    }
}
?>

See also PHP RFC: Allow trailing comma in parameter list.

9.553.1. Suggestions

Short name Php/SignatureTrailingComma
Rulesets CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP73, CompatibilityPHP74
Php Version 8.0+
Severity Minor
Time To Fix Quick (30 mins)

9.554. Silently Cast Integer

Those are integer literals that are cast to a float when running PHP. They are too big for the current PHP version, and PHP resorts to cast them into a float, which has a much larger capacity but a lower precision.

Compare your literals to PHP_MAX_INT (typically 9223372036854775807) and PHP_MIN_INT (typically -9223372036854775808). This applies to binary (0b10101…), octal (0123123…) and hexadecimal (0xfffff…) too.

<?php

echo 0b1010101101010110101011010101011010101011010101011010101011010111;
//6173123008118052203
echo 0b10101011010101101010110101010110101010110101010110101010110101111;
//1.2346246016236E+19

echo 0123123123123123123123;
//1498121094048818771
echo 01231231231231231231231;
//1.1984968752391E+19

echo 0x12309812311230;
//5119979279159856
echo 0x12309812311230fed;
//2.0971435127439E+19

echo 9223372036854775807; //PHP_MAX_INT
//9223372036854775807
echo 9223372036854775808;
9.2233720368548E+18

?>

See also Integer overflow.

9.554.1. Suggestions

  • Make sure hexadecimal numbers have the right number of digits : generally, it is 15, but it may depends on your PHP version.
Short name Type/SilentlyCastInteger
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples MediaWiki

9.555. Similar Integers

This analysis reports all integer values that are expressed in different format.

<?php

// Three ways to write 10 (more available)
$a = 10;
$b = 012;
$x = 0xA;

// 7 is expressed in one way only
$d = 7;
$d = 7;

// Four ways to write 11 (more available)
$a = 11;
$b = 013;
$x = 0xB;
$x = -+-11;

// Expressions are not counted

?>

9.555.1. Suggestions

Short name Type/SimilarIntegers
Rulesets Coding Conventions, Semantics
Severity Minor
Time To Fix Quick (30 mins)

9.556. Simple Global Variable

The global keyword should only be used with simple variables. Since PHP 7, it cannot be used with complex or dynamic structures.

<?php

// Forbidden in PHP 7
global $normalGlobal;

// Forbidden in PHP 7
global $$variable->global ;

// Tolerated in PHP 7
global ${$variable->global};

?>
Short name Php/GlobalWithoutSimpleVariable
Rulesets CompatibilityPHP70
Php Version With PHP 7.0 and older
Severity Critical
Time To Fix Slow (1 hour)

9.557. Simple Switch

Switches are faster when relying only on integers or strings.

Since PHP 7.2, simple switches that use only strings or integers are optimized. The gain is as great as the switch is big.

<?php

// Optimized switch.
switch($b) {
    case "a":
        break;
    case "b":
        break;
    case "c":
        break;
    case "d":
        break;
    default :
        break;
}

// Unoptimized switch.
// Try moving the foo() call in the default, to keep the rest of the switch optimized.
switch($c) {
    case "a":
        break;
    case foo($b):
        break;
    case "c":
        break;
    case "d":
        break;
    default :
        break;
}

?>

See also PHP 7.2’s “switch” optimisations.

9.557.1. Suggestions

  • Split the switch between literal and dynamic cases
  • Remove the dynamic cases from the switch
Short name Performances/SimpleSwitch
Rulesets Performances
Php Version With PHP 7.2 and more recent
Severity Major
Time To Fix Quick (30 mins)

9.558. Simplify Regex

Avoid using regex when the searched string or the replacement are simple enough.

PRCE regex are a powerful way to search inside strings, but they also come at the price of performance. When the query is simple enough, try using strpos() or stripos() instead.

<?php

// simple preg calls
if (preg_match('/a/', $string))  {}
if (preg_match('/b/i', $string)) {} // case insensitive

// light replacements
if( strpos('a', $string)) {}
if( stripos('b', $string)) {}       // case insensitive

?>

9.558.1. Suggestions

  • Use str_replace(), strtr() or even strpos()
Short name Structures/SimplePreg
Rulesets Performances
Severity Major
Time To Fix Quick (30 mins)
Examples Zurmo, OpenConf

9.559. Slice Arrays First

Always start by reducing an array before applying some transformation on it. The shorter array will be processed faster.

<?php

// fast version
$a = array_map('foo', array_slice($array, 2, 5));

// slower version
$a = array_slice(array_map('foo', $array), 2, 5);
?>

The gain produced here is greater with longer arrays, or greater reductions. They may also be used in loops. This is a micro-optimisation when used on short arrays.

9.559.1. Suggestions

  • Use the array transforming function on the result of the array shortening function.
Short name Arrays/SliceFirst
Rulesets Performances, Suggestions
Severity Minor
Time To Fix Quick (30 mins)
Examples WordPress

9.560. Slow Functions

Avoid using those slow native PHP functions, and replace them with alternatives.

<?php

$array = source();

// Slow extraction of distinct values
$array = array_unique($array);

// Much faster extraction of distinct values
$array = array_keys(array_count_values($array));

?>
Slow Function Faster
array_diff() array_intersect() array_key_exists() array_map() array_search() array_udiff() array_uintersect() array_unshift() array_walk() in_array() preg_replace() strstr() uasort() uksort() usort() array_unique() foreach() foreach() isset() and array_key_exists() foreach() array_flip() and isset() Use another way Use another way Use another way foreach() isset() strpos() strpos() Use another way Use another way Use another way array_keys() and array_count_values()

array_unique() has been accelerated in PHP 7.2 and may be used directly from this version on : Optimize `array_unique() <https://github.com/php/php-src/commit/6c2c7a023da4223e41fea0225c51a417fc8eb10d>`_.

array_key_exists() has been accelerated in PHP 7.4 and may be used directly from this version on : Implement ZEND_ARRAY_KEY_EXISTS opcode to speed up `array_key_exists() <https://github.com/php/php-src/pull/3360>`_.

9.560.1. Suggestions

  • Replace the slow function with a faster version
  • Remove the usage of the slow function
Short name Performances/SlowFunctions
Rulesets Performances
Severity Major
Time To Fix Quick (30 mins)
ClearPHP avoid-those-slow-functions
Examples ChurchCRM, SuiteCrm

9.561. Sqlite3 Requires Single Quotes

The escapeString() method from SQLite3 doesn’t escape ", but only '.

<?php

// OK. escapeString is OK with '
$query = "SELECT * FROM table WHERE col = '".$sqlite->escapeString($x)."'";

// This is vulnerable to " in $x
$query = 'SELECT * FROM table WHERE col = "'.$sqlite->escapeString($x).'"';

?>

To properly handle quotes and NUL characters, use bindParam() instead.

Quote from the PHP manual comments : The reason this function doesn't escape double quotes is because double quotes are used with names (the equivalent of backticks in MySQL), as in table or column names, while single quotes are used for values.

See also SQLite3::escapeString.

9.561.1. Suggestions

  • Use prepared statements whenever possible
  • Switch the query to use single quote
Short name Security/Sqlite3RequiresSingleQuotes
Rulesets Security
Severity Major
Time To Fix Slow (1 hour)

9.562. Static Global Variables Confusion

PHP can’t have variable that are both static and variable. While the syntax is legit, the variables will be alternatively global or static.

It is recommended to avoid using the same name for a global variable and a static variable.

<?php

function foo() {
    $a = 1; // $a is a local variable

    global $a; // $a is now a global variable

    static $a; // $a is not w static variable
}

?>

9.562.1. Suggestions

  • Avoid using static variables
  • Avoid using global variables
  • Avoid using the same name for static and global variables
Short name Structures/SGVariablesConfusion
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.563. Static Loop

Static loop may be preprocessed.

It looks like the following loops are static : the same code is executed each time, without taking into account loop variables.

<?php

// Static loop
$total = 0;
for($i = 0; $i < 10; $i++) {
    $total += $i;
}

// The above loop may be replaced by (with some math help)
$total = 10 * (10  + 1) / 2;

// Non-Static loop (the loop depends on the size of the array)
$n = count($array);
for($i = 0; $i < $n; $i++) {
    $total += $i;
}

?>

It is possible to create loops that don’t use any blind variables, though this is fairly rare. In particular, calling a method may update an internal pointer, like next() or SimpleXMLIterator\:\:`next() <https://www.php.net/next>`_.

It is recommended to turn a static loop into an expression that avoid the loop. For example, replacing the sum of all integers by the function $n * ($n + 1) / 2, or using array_sum().

This analysis doesn’t detect usage of variables with compact.

9.563.1. Suggestions

  • Precalculate the result of that loop and removes it altogether
  • Check that the loop is not missing a blind variable usage
  • Replace the usage of a loop with a native PHP call : for example, with str_repeat(). Although the loop is still here, it usually reflects better the intend.
Short name Structures/StaticLoop
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)

9.564. Static Methods Called From Object

Static methods may be called without instantiating an object. As such, they never interact with the special variable ‘$this’, as they do not depend on object existence.

Besides this, static methods are normal methods that may be called directly from object context, to perform some utility task.

To maintain code readability, it is recommended to call static method in a static way, rather than within object context.

<?php
    class x {
        static function y( ) {}
    }

    $z = new x( );

    $z->y( ); // Readability : no one knows it is a static call
    x::y( );  // Readability : here we know
?>
Short name Classes/StaticMethodsCalledFromObject
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.565. Static Methods Can’t Contain $this

Static methods are also called class methods : they may be called even if the class has no instantiated object. Thus, the local variable $this won’t exist, PHP will set it to NULL as usual.

<?php

class foo {
    // Static method may access other static methods, or property, or none.
    static function staticBar() {
        // This is not possible in a static method
        return self::otherStaticBar() . static::$staticProperty;
    }

    static function bar() {
        // This is not possible in a static method
        return $this->property;
    }
}

?>

Either this is not a static method, which is fixed by removing the static keyword, or replace all $this mention by static properties Class\:\:$property.

See also Static Keyword <https://www.php.net/manual/en/language.oop5.`static.php>`_

9.565.1. Suggestions

  • Remove any $this usage
  • Turn any $this usage into a static call : $this->foo() => self::foo()
Short name Classes/StaticContainsThis
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-static-this
Examples xataface, SugarCrm

9.566. Strange Name For Constants

Those constants looks like a typo from other names.

<?php

// This code looks OK : DIRECTORY_SEPARATOR is a native PHP constant
$path = $path . DIRECTORY_SEPARATOR . $file;

// Strange name DIRECOTRY_SEPARATOR
$path = $path . DIRECOTRY_SEPARATOR . $file;

?>

9.566.1. Suggestions

  • Fix any typo in the spelling of the constants
  • Tell us about common misspelling so we can upgrade this analysis
Short name Constants/StrangeName
Rulesets Analyze, Analyze
Severity Minor
Time To Fix Slow (1 hour)

9.567. Strange Name For Variables

Variables with strange names. They might be a typo, or bear strange patterns.

Any variable with three identical letter in a row are considered as strange. 2 letters in a row is classic, and while three letters may happen, it is rare enough.

A list of classic typo is also used to find such variables.

This analysis is case-sensitive.

<?php

class foo {
    function bar() {
        // Strange name $tihs
        return $tihs;
    }

    function barbar() {
        // variables with blocks of 3 times the same character are reported
        // Based on Alexandre Joly's tweet
        $aaa = $bab + $www;
    }
}

?>

See also #QuandLeDevALaFleme.

9.567.1. Suggestions

  • Fix the name of the variable
  • Rename the variable to something better
  • Drop the variable
Short name Variables/StrangeName
Rulesets none
Severity Minor
Time To Fix Slow (1 hour)
Examples FuelCMS, PhpIPAM

9.568. Strict Comparison With Booleans

Strict comparisons prevent from mistaking an error with a false.

Boolean values may be easily mistaken with other values, especially when the function may return integer or boolean as a normal course of action.

It is encouraged to use strict comparison === or !== when booleans are involved in a comparison.

<?php

// distinguish between : $b isn't in $a, and, $b is at the beginning of $a
if (strpos($a, $b) === 0) {
    doSomething();
}

// DOES NOT distinguish between : $b isn't in $a, and, $b is at the beginning of $a
if (strpos($a, $b)) {
    doSomething();
}

// will NOT mistake 1 and true
$a = array(0, 1, 2, true);
if (in_array($a, true, true)) {
    doSomething();
}

// will mistake 1 and true
$a = array(0, 1, 2, true);
if (in_array($a, true)) {
    doSomething();
}

?>

switch() structures always uses == comparisons.

Native function in_array() has a third parameter to make it use strict comparisons.

9.568.1. Suggestions

  • Use strict comparison whenever possible
Short name Structures/BooleanStrictComparison
Rulesets Analyze, Suggestions, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples Phinx, Typo3

9.569. String Initialization

It used to be possible to initialize a variable with an string, and use it as an array. It is not the case anymore in PHP 7.1.

<?php

// Initialize arrays with array()
$a = array();
$a[3] = 4;

// Don't start with a string
$a = '';
$a[3] = 4;
print $a;

// Don't start with a string
if (is_numeric($a)) {
    $a[] = $a;
}

?>

See also PHP 7.1 no longer converts string to arrays the first time a value is assigned with square bracket notation.

9.569.1. Suggestions

  • Always initialize arrays with an empty array(), not a string.
Short name Arrays/StringInitialization
Rulesets CompatibilityPHP71
Severity Minor
Time To Fix Quick (30 mins)

9.570. String May Hold A Variable

Those strings looks like holding a variable.

Single quotes and Nowdoc syntax may include $ signs that are treated as literals, and not replaced with a variable value.

However, there are some potential variables in those strings, making it possible for an error : the variable was forgotten and will be published as such. It is worth checking the content and make sure those strings are not variables.

<?php

$a = 2;

// Explicit variable, but literal effect is needed
echo '$a is '.$a;

// One of the variable has been forgotten
echo '$a is $a';

// $CAD is not a variable, rather a currency unit
$total = 12;
echo $total.' $CAD';

// $CAD is not a variable, rather a currency unit
$total = 12;

// Here, $total has been forgotten
echo <<<'TEXT'
$total $CAD
TEXT;

?>
Short name Type/StringHoldAVariable
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)

9.571. Strings With Strange Space

An invisible space may be mistaken for a normal space.

However, PHP does straight comparisons, and may fail at recognizing. This analysis reports when it finds such strange spaces inside strings.

PHP doesn’t mistake space and tables for whitespace when tokenizing the code.

This analysis doesn’t report Unicode Codepoint Notation : those are visible in the code.

<?php

// PHP 7 notation,
$a = \u{3000};
$b = ;

// Displays false
var_dump($a === $b);

?>

See also Unicode spaces, and disallow irregular whitespace (no-irregular-whitespace).

9.571.1. Suggestions

  • Replace the odd spaces with a normal space
  • If unsecable spaces are important for presentation, add them at the templating level.
Short name Type/StringWithStrangeSpace
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples OpenEMR, Thelia

9.572. Strpos()-like Comparison

The result of that function may be mistaken with an error.

strpos(), along with several PHP native functions, returns a string position, starting at 0, or false, in case of failure.

<?php

// This is the best comparison
if (strpos($string, 'a') === false) { }

// This is OK, as 2 won't be mistaken with false
if (strpos($string, 'a') == 2) { }

// strpos is one of the 26 functions that may behave this way
if (preg_match($regex, $string)) { }

// This works like above, catching the value for later reuse
if ($a = strpos($string, 'a')) { }

// This misses the case where 'a' is the first char of the string
if (strpos($string, 'a')) { }

// This misses the case where 'a' is the first char of the string, just like above
if (strpos($string, 'a') == 0) { }

?>

It is recommended to check the result of strpos() with === or !==, so as to avoid confusing 0 and false.

This analyzer list all the strpos()-like functions that are directly compared with == or !=. preg_match(), when its first argument is a literal, is omitted : this function only returns NULL in case of regex error.

The full list is the following :

In PHP 8.0, str_contains() will do the expected job of strpos(), with less confusion.

See also strpos not working correctly.

9.572.1. Suggestions

  • Use identity comparisons, for 0 values : === instead of ==, etc.
  • Compare with other exact values than 0 : strpos() == 2
  • Use str_contains()
Short name Structures/StrposCompare
Rulesets Analyze, Top10, CI-checks
Severity Major
Time To Fix Quick (30 mins)
ClearPHP strict-comparisons
Examples Piwigo, Thelia

9.573. Strtr Arguments

Strtr() replaces characters by others in a string. When using strings, strtr() replaces characters as long as they have a replacement. All others are ignored.

In particular, strtr() works on strings of the same size, and cannot be used to remove chars.

<?php

$string = 'abcde';
echo strtr($string, 'abc', 'AB');
echo strtr($string, 'ab', 'ABC');
// displays ABcde
// c is ignored each time

// strtr can't remove a char
echo strtr($string, 'a', '');
// displays a

?>

See also strtr.

9.573.1. Suggestions

  • Check the call to strtr() and make sure the arguments are of the same size
  • Replace strtr() with str_replace(), which works with strings and array, not chars
  • Replace strtr() with preg_match(), which works with patterns and not chars
Short name Php/StrtrArguments
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Instant (5 mins)
Examples SuiteCrm

9.574. Substr To Trim

When removing the first or the last character of a string, trim() does a more readable job.

trim(), ltrim() and rtrim() accept a string as second argument. Those will all be removed from the endings of the string.

<?php

$a = '$drop the dollar';
$b = substr($a, 1); // drop the first char
$b = ltrim($a, '$'); // remove the initial '$'s


$b = substr($a, 1);     // replace with ltrim()

$b = substr($a, 0, -1); // replace with rtrim()

$b = substr($a, 1, -1); // replace with trim()

?>

trim() will remove all occurrences of the requested char(). This may remove a loop with substr(), or remove more than is needed.

trim() doesn’t work with multi-bytes strings, but so does substr(). For that, use mb_substr(), as there isn’t any mb_trim function (yet).

See also trim, ltrim, rtrim.

9.574.1. Suggestions

  • Replace substr() with trim(), ltrim() or rtrim().
Short name Structures/SubstrToTrim
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.575. Substring First

Always start by reducing a string before applying some transformation on it. The shorter string will be processed faster.

<?php

// fast version
$result = strtolower(substr($string, $offset, $length));

// slower version
$result = substr(strtolower($string), $offset, $length);
?>

The gain produced here is greater with longer strings, or greater reductions. They may also be used in loops. This is a micro-optimisation when used on short strings and single string reductions.

This works with any reduction function instead of substr(), like trim(), iconv(), etc.

9.575.1. Suggestions

  • Always reduce the string first, then apply some transformation
Short name Performances/SubstrFirst
Rulesets Performances, Suggestions, Top10
Severity Minor
Time To Fix Instant (5 mins)
Examples SPIP, PrestaShop

9.576. Suspicious Comparison

The comparison seems to be misplaced.

A comparison happens in the last argument, while the actual function expect another type : this may be the case of a badly placed parenthesis.

<?php

// trim expect a string, a boolean is given.
if (trim($str === '')){

}

// Just move the first closing parenthesis to give back its actual meaning
if (trim($str) === ''){

}

?>

Original idea by Vladimir Reznichenko.

9.576.1. Suggestions

  • Remove the comparison altogether
  • Move the comparison to its right place : that, or more the parenthesis.
  • This may be what is intended : just leave it.
Short name Structures/SuspiciousComparison
Rulesets Analyze
Severity Major
Time To Fix Instant (5 mins)
Examples PhpIPAM, ExpressionEngine

9.577. Swapped Arguments

Overwritten methods must be compatible, but argument names is not part of that compatibility.

Methods with the same name, in two classes of the same hierarchy, must be compatible for typehint, default value, reference. The name of the argument is not taken into account when checking such compatibility, at least until PHP 7.4.

<?php

class x {
    function foo($a, $b) {}

    function bar($a, $b) {}
}

class y extends x {
    // foo is compatible (identical) with the above class
    function foo($a, $b) {}

    // bar is compatible with the above class, yet, the argument might not receive what they expect.
    function bar($b, $a) {}
}

?>

This analysis reports argument lists that differs in ordering. This analysis doesn’t report argument lists that also differs in argument names.

9.577.1. Suggestions

  • Make sure the names of the argument are in the same order in all classes and interfaces
Short name Classes/SwappedArguments
Rulesets Analyze
Severity Critical
Time To Fix Quick (30 mins)

9.578. Switch Fallthrough

A switch with fallthrough is prone to errors.

A fallthrough happens when a case or default clause in a switch statement is not finished by a break (or equivalent); CWE report this as a security concern, unless well documented.

A fallthrough may be used as a feature. Then, it is indistinguishable from an error.

When the case block is empty, this analysis doesn’t report it : the case is then used as an alias.

<?php
switch($variable) {
    case 1 :   // case 1 is not reported, as it actually shares the same body as case 33
    case 33 :
        break ;
    case 2 :
        break ;
    default:
        ++$a;
    case 4 :
        break ;
}
?>

This analysis doesn’t take into account comments about the fallthrough.

See also CWE-484: Omitted `Break Statement in Switch <https://cwe.mitre.org/data/definitions/484.html>`_ and Rule: no-switch-case-fall-through.

9.578.1. Suggestions

  • Make separate code for each case. Always use break at the end of a case or default.
Short name Structures/Fallthrough
Rulesets Security
Severity Minor
Time To Fix Instant (5 mins)

9.579. Switch To Switch

The following structures are based on if / elseif / else. Since they have more than three conditions (not withstanding the final else), it is recommended to use the switch structure, so as to make this more readable.

On the other hand, switch() structures with less than 3 elements should be expressed as a if / else structure.

Note that if condition that uses strict typing (=== or !==) can’t be converted to switch() as the latter only performs == or != comparisons.

<?php

if ($a == 1) {

} elseif ($a == 2) {

} elseif ($a == 3) {

} elseif ($a == 4) {

} else {

}

// Better way to write long if/else lists
switch ($a) {
    case 1 :
        doSomething(1);
        break 1;

    case 2 :
        doSomething(2);
        break 1;

    case 3 :
        doSomething(3);
        break 1;

    case 4 :
        doSomething(4);
        break 1;

    default :
        doSomething();
        break 1;
}

?>

Note that simple switch statement, which compare a variable to a literal are optimised in PHP 7.2 and more recent. This gives a nice performance boost, and keep code readable.

See also PHP 7.2’s switch optimisations and Is Your Code Readable By Humans? Cognitive Complexity Tells You.

9.579.1. Suggestions

  • Use a switch statement, rather than a long string of if/else
  • Use a match() statement, rather than a long string of if/else (PHP 8.0 +)
Short name Structures/SwitchToSwitch
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples Thelia, XOOPS

9.580. Switch With Too Many Default

Switch statements should only hold one default, not more. Check the code and remove the extra default.

PHP 7.0 won’t compile a script that allows for several default cases.

Multiple default happens often with large switch().

<?php

switch($a) {
    case 1 :
        break;
    default :
        break;
    case 2 :
        break;
    default :  // This default is never reached
        break;
}

?>

9.580.1. Suggestions

  • Remove the useless default : it may be the first, or the last. In case of ambiguity, keep the first, as it is the one being used at the moment.
Short name Structures/SwitchWithMultipleDefault
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and older
Severity Minor
Time To Fix Quick (30 mins)

9.581. Switch Without Default

Always use a default statement in switch().

Switch statements hold a number of ‘case’ that cover all known situations, and a ‘default’ one which is executed when all other options are exhausted.

<?php

// Missing default
switch($format) {
    case 'gif' :
        processGif();
        break 1;

    case 'jpeg' :
        processJpeg();
        break 1;

    case 'bmp' :
        throw new UnsupportedFormat($format);
}
// In case $format is not known, then switch is ignored and no processing happens, leading to preparation errors


// switch with default
switch($format) {
    case 'text' :
        processText();
        break 1;

    case 'jpeg' :
        processJpeg();
        break 1;

    case 'rtf' :
        throw new UnsupportedFormat($format);

    default :
        throw new UnknownFileFormat($format);
}
// In case $format is not known, an exception is thrown for processing

?>

Most of the time, switch() do need a default case, so as to catch the odd situation where the ‘value is not what it was expected’. This is a good place to catch unexpected values, to set a default behavior.

9.581.1. Suggestions

  • Add a default case
Short name Structures/SwitchWithoutDefault
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-switch-without-default
Examples Zencart, Traq

9.582. Ternary In Concat

Ternary and coalesce operator have higher priority than dot ‘.’ for concatenation. This means that :

<?php
  // print B0CE as expected
  print 'B'.$b.'C'. ($b > 1 ? 'D') : 'E';

  // print E, instead of B0CE
  print 'B'.$b.'C'. $b > 1 ? 'D' : 'E';

  print 'B'.$b.'C'. $b > 1 ? 'D' : 'E';
?>

prints actually ‘E’, instead of the awaited ‘B0CE’.

To be safe, always add parenthesis when using ternary operator with concatenation.

See also Operator Precedence.

9.582.1. Suggestions

  • Use parenthesis
  • Avoid ternaries and coalesce operators inside a string
Short name Structures/TernaryInConcat
Rulesets Analyze, CI-checks
Severity Critical
Time To Fix Quick (30 mins)
Examples TeamPass

9.583. Test Then Cast

A test is run on the value, but the cast value is later used.

The cast may introduce a distortion to the value, and still lead to the unwanted situation. For example, comparing to 0, then later casting to an int. The comparison to 0 is done without casting, and as such, 0.1 is different from 0. Yet, (int) 0.1 is actually 0, leading to a Division by 0 error.

<?php

// Here. $x may be different from 0, but (int) $x may be 0
$x = 0.1;

if ($x != 0) {
    $y = 4 / (int) $x;
}

// Safe solution : check the cast value.
if ( (int) $x != 0) {
    $y = 4 / (int) $x;
}

?>

9.583.1. Suggestions

  • Test with the cast value
Short name Structures/TestThenCast
Rulesets Analyze
Severity Major
Time To Fix Instant (5 mins)
Examples Dolphin, SuiteCrm

9.584. Throw Functioncall

The throw keyword expects to use an exception. Calling a function to prepare that exception before throwing it is possible, but forgetting the new keyword is also possible.

<?php

// Forgotten new
throw \RuntimeException('error!');

// Code is OK, function returns an exception
throw getException(ERROR_TYPE, 'error!');

function getException(ERROR_TYPE, $message) {
    return new \RuntimeException($messsage);
}

?>

When the new keyword is forgotten, then the class constructor is used as a function name, and now exception is emitted, but an Undefined function fatal error is emitted.

See also Exceptions.

9.584.1. Suggestions

  • Add the new operator to the call
  • Make sure the function is really a functioncall, not a class name
Short name Exceptions/ThrowFunctioncall
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Instant (5 mins)
Examples SugarCrm, Zurmo

9.585. Throw In Destruct

According to the manual, Attempting to throw an exception from a destructor (called in the time of script termination) causes a fatal error.

The destructor may be called during the lifespan of the script, but it is not certain. If the exception is thrown later, the script may end up with a fatal error.

Thus, it is recommended to avoid throwing exceptions within the __destruct method of a class.

<?php

// No exception thrown
class Bar {
    function __construct() {
        throw new Exception('__construct');
    }

    function __destruct() {
        $this->cleanObject();
    }
}

// Potential crash
class Foo {
    function __destruct() {
        throw new Exception('__destruct');
    }
}

?>

See also Constructors and Destructors.

9.585.1. Suggestions

  • Remove any exception thrown from a destructor
Short name Classes/ThrowInDestruct
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)

9.586. Throw Was An Expression

Throw used to be an expression. In PHP 7.0, there were some location where one couldn’t use a throw : this was the case for arrow functions, which expect one expression as function’s body.

Using throw as an instruction makes the code incompatible with PHP 7 version and older.

<?php

// Valid in PHP 8.0 and more recent
$fn = fn($a) => throw new Exception($a);

?>

See also Throw Expression and Exceptions.

9.586.1. Suggestions

Short name Php/ThrowWasAnExpression
Rulesets CompatibilityPHP72, CompatibilityPHP73, CompatibilityPHP74
Php Version 8.0+
Severity Major
Time To Fix Quick (30 mins)

9.587. Throws An Assignement

It is possible to throw an exception, and, in the same time, assign this exception to a variable.

However, the variable will never be used, as the exception is thrown, and any following code is not executed, unless the exception is caught in the same scope.

<?php

    // $e is useful, though not by much
    $e = new() Exception();
    throw $e;

    // $e is useless
    throw $e = new Exception();

?>

9.587.1. Suggestions

  • Drop the assignation
Short name Structures/ThrowsAndAssign
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)

9.588. Timestamp Difference

time() and microtime() shouldn’t be used to calculate duration.

time() and microtime() are subject to variations, depending on system clock variations, such as daylight saving time difference (every spring and fall, one hour variation), or leap seconds, happening on June, 30th or December 31th, as announced by IERS.

<?php

// Calculating tomorow, same hour, the wrong way
// tomorrow is not always in 86400s, especially in countries with daylight saving
$tomorrow = time()  + 86400;

// Good way to calculate tomorrow
$datetime = new DateTime('tomorrow');

?>

When the difference may be rounded to a larger time unit (rounding the difference to days, or several hours), the variation may be ignored safely.

When the difference is very small, it requires a better way to measure time difference, such as Ticks <https://www.php.net/manual/en/control-structures.declare.php#control-structures.declare.ticks>’_, `ext/hrtime <https://www.php.net/manual/en/book.hrtime.php>’_, or including a check on the actual time zone (``ini_get()` with ‘date.timezone’).

See also PHP DateTime difference – it’s a trap! and PHP Daylight savings bug?.

9.588.1. Suggestions

  • For small time intervals, use hrtime() functions
  • For larger time intervals, use add() method with DateTime
Short name Structures/TimestampDifference
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Slow (1 hour)
Examples Zurmo, shopware

9.589. Too Long A Block

The loop is operating on a block that is too long.

This analysis is applied to loops (for, foreach, while, do..while) and if/then/else/elseif structures.

Then length of a block is managed with the ``longBlock``parameter. By default, it is 200 lines, from beginning to the end. Comments are taken into account.

<?php

$i = 0;
do {
    // 200 lines of PHP code

    ++$i;
} while($i < 100);

?>

9.589.1. Suggestions

  • Move the code of the block to an method or a function
  • Move part of the code of the block to methods or functions
  • Extract repeated patterns and use them
Name Default Type Description
longBlock 200 integer Size of a block for it to be too long. A block is commanded by a for, foreach, while, do…while, if/then else structure.
Short name Structures/LongBlock
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.590. Too Many Array Dimensions

When arrays a getting to many nesting.

<?php

$a          = array();   // level 1;
$a[1]       = array();   // level 2
$a[1][2]    = array();   // level 3 : still valid by default
$a[1][2][3] = array();   // level 4

?>

PHP has no limit, and accepts any number of nesting levels. Yet, this is usually very memory hungry.

9.590.1. Suggestions

Name Default Type Description
maxDimensions 3 integer Number of valid dimensions in an array.
Short name Arrays/TooManyDimensions
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.591. Too Many Children

Classes that have more than 15 children. It is worth checking if they cannot be refactored in anyway.

The threshold of 15 children can be configured. There is no technical limitation of the number of children and grand-children for a class.

The analysis doesn’t work recursively : only direct generations are counted. Only children that can be found in the code are counted.

<?php

// parent class
// calling it grandparent to avoid confusion with 'parent'
class grandparent {}


class children1 extends grandparent {}
class children2 extends grandparent {}
class children3 extends grandparent {}
class children4 extends grandparent {}
class children5 extends grandparent {}
class children6 extends grandparent {}
class children7 extends grandparent {}
class children8 extends grandparent {}
class children9 extends grandparent {}
class children11 extends grandparent {}
class children12 extends grandparent {}
class children13 extends grandparent {}
class children14 extends grandparent {}
class children15 extends grandparent {}
class children16 extends grandparent {}
class children17 extends grandparent {}
class children18 extends grandparent {}
class children19 extends grandparent {}

?>

See also Why is subclassing too much bad (and hence why should we use prototypes to do away with it)?.

9.591.1. Suggestions

  • Split the original class into more specialised classes
Name Default Type Description
childrenClassCount 15 integer Threshold for too many children classes for one class.
Short name Classes/TooManyChildren
Rulesets Suggestions
Severity Minor
Time To Fix Slow (1 hour)
Examples Typo3, Woocommerce

9.592. Too Many Dereferencing

Linking too many properties and methods, one to the other.

This analysis counts both static calls and normal call; methods, properties and constants. It also takes into account arrays along the way.

The default limit of chaining methods and properties is set to 7 by default.

<?php

// 9 chained calls.
$main->getA()->getB()->getC()->getD()->getE()->getF()->getG()->getH()->getI()->property;

?>

Too many chained methods is harder to read.

9.592.1. Suggestions

Name Default Type Description
tooManyDereferencing 7 integer Maximum number of dereferencing.
Short name Classes/TooManyDereferencing
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.593. Too Many Finds

Too many methods called ‘find*’ in this class. It is may be time to consider the Specification pattern.

<?php

// quite a fishy interface
interface UserInterface {
    public function findByEmail($email);
    public function findByUsername($username);
    public function findByFirstName($firstname);
    public function findByLastName($lastname);
    public function findByName($name);
    public function findById($id);

    public function insert($user);
    public function update($user);
}

?>

See also On Taming Repository Classes in Doctrine , On Taming Repository Classes in Doctrine… Among other things., specifications.

Name Default Type Description
minimumFinds 5 integer Minimal number of prefixed methods to report.
findPrefix find string list of prefix to use when detecting the ‘find’. Comma-separated list, case insensitive.
findSuffix   string list of fix to use when detecting the ‘find’. Comma-separated list, case insensitive.
Short name Classes/TooManyFinds
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)

9.594. Too Many Injections

When a class is constructed with more than four dependencies, it should be split into smaller classes.

<?php

// This class relies on 5 other instances.
// It is probably doing too much.
class Foo {
    public function __construct(
            A $a,
            B $b,
            C $c,
            D $d
            E $e ) {
        $this->a = $a;
        $this->b = $b;
        $this->d = $d;
        $this->d = $d;
        $this->e = $e;
    }
}

?>

See also Dependency Injection Smells.

9.594.1. Suggestions

  • Split the class into smaller classes. Try to do less in that class.
Name Default Type Description
injectionsCount 5 integer Threshold for too many injected parameters for one class.
Short name Classes/TooManyInjections
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples NextCloud, Thelia

9.595. Too Many Local Variables

Too many local variables were found in the methods. When over 15 variables are found in such a method, a violation is reported.

Local variables exclude globals (imported with global) and arguments. Local variable include static variables.

When too many variables are used in a function, it is a code smells. The function is trying to do too much and needs extra space for juggling. Beyond 15 variables, it becomes difficult to keep track of their name and usage, leading to confusion, overwriting or hijacking.

<?php

// This function is OK : 3 vars are arguments, 3 others are globals.
function a20a3g3($a1, $a2, $a3) {
    global $a4, $a5, $a6;

    $a1  = 1;
    $a2  = 2;
    $a3  = 3 ;
    $a4  = 4 ;
    $a5  = 5 ;
    $a6  = 6 ;
    $a7  = 7 ;
    $a8  = 8 ;
    $a9  = 9 ;
    $a10 = 10;
    $a11  = 11;
    $a12  = 12;
    $a13  = 13 ;
    $a14  = 14 ;
    $a15  = 15 ;
    $a16  = 16 ;
    $a17  = 17 ;
    $a18  = 18 ;
    $a19  = 19 ;
    $a20 = 20;

}

// This function has too many variables
function a20() {

    $a1  = 1;
    $a2  = 2;
    $a3  = 3 ;
    $a4  = 4 ;
    $a5  = 5 ;
    $a6  = 6 ;
    $a7  = 7 ;
    $a8  = 8 ;
    $a9  = 9 ;
    $a10 = 10;
    $a11  = 11;
    $a12  = 12;
    $a13  = 13 ;
    $a14  = 14 ;
    $a15  = 15 ;
    $a16  = 16 ;
    $a17  = 17 ;
    $a18  = 18 ;
    $a19  = 19 ;
    $a20 = 20;

}

?>

9.595.1. Suggestions

  • Remove some of the variables, and inline them
  • Break the big function into smaller ones
  • Find repeated code and make it a separate function
Name Default Type Description
tooManyLocalVariableThreshold 15 integer Minimal number of variables in one function or method to report.
Short name Functions/TooManyLocalVariables
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples HuMo-Gen

9.596. Too Many Native Calls

Avoid stuffing too many PHP native call inside another functioncall.

For readability reasons, or, more often, for edge case handling, it is recommended to avoid nesting too many PHP native calls.

This analysis reports any situation where more than 3 PHP native calls are nested.

<?php

// Too many nested functions
$cleanArray = array_unique(array_keys(array_count_values(array_column($source, 'x'))));

// Avoid warning when source is empty
$extract = array_column($source, 'x');
if (empty($extract)) {
    $cleanArray = array();
} else {
    $cleanArray = array_unique(array_keys(array_count_values($extract)));
}

// This is not readable, although it is short.
// It may easily get out of hand.
echo chr(80), chr(72), chr(80), chr(32), ' is great!';

?>
Name Default Type Description
nativeCallCounts 3 integer Number of native calls found inside another call.
Short name Php/TooManyNativeCalls
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples SPIP

9.597. Too Many Parameters

Method has too many parameters. Exakat has a default parameter count which may be configured.

A method that needs more than 8 parameters is trying to do too much : it should be reviewed and split into smaller methods.

<?php

// This methods has too many parameters.
function alertSomeone($name, $email, $title, $message, $attachements, $signature, $bcc, $cc, $extra_headers) {
    /* too much code here */
}

?>

See also How many parameters is too many ? and Too Many Parameters.

9.597.1. Suggestions

  • Reduce the number of parameters to a lower level
  • Break the function into smaller functions
  • Turn the function into a class
Name Default Type Description
parametersCount 8 integer Minimal number of parameters to report.
Short name Functions/TooManyParameters
Rulesets Suggestions
Examples WordPress, ChurchCRM

9.598. Too Much Indented

Reports methods that are using more than one level of indentation on average.

Indentations levels are counted for each for, foreach, if…then, while, do..while, try..catch..finally structure met. Compulsory expressions, such as conditions, are not counted in the total. Levels of indentation start at 0 (no indentation needed)

This analysis targets methods which are build around large conditions : the actual useful code is nested inside the branches of the if/then/else (for example).

The default threshold indentationAverage of 1 is a good start for spotting large methods with big conditional code, and will leave smaller methods, even when they only contain one if/then. Larger methods shall be refactored in smaller size.

The parameter minimumSize set aside methods which are too small for refactoring.

<?php

// average 0
function foo0() {
    $a = rand(1,2);
    $a *= 3;

    return $a;
}

// average 0.66 = (0 + 1 + 1) / 3
function foo0_66() {
    // if () is at level 0
    if ($a == 2) { // condition is not counted
        $a = 1;    // level 1
    } else {
        $a = 2;    // level 1
    }
}

// average 1 = (0 + 2 + 1 + 1) / 4
function foo1() {
    // if () is at level 0
    if ($a == 2) {
        // if () is at level 1
        if ($a == 2) {
            $a = 1; // level 2
        }
        $a = 1; // level 1
    } else {
        $a = 2; // level 1
    }
}

?>

This analysis is distinct from Structures/MaxLevelOfIdentation, which only reports the highest level of indentation. This one reports how one method is build around one big

See also Max Level Of Nesting.

9.598.1. Suggestions

  • Refactor the method to reduce the highest level of indentation
  • Refactor the method move some of the code to external methods.
Name Default Type Description
indentationAverage 1 real Minimal average of indentation in a method to report. Default is 1.0, which means that the method is on average at one level of indentation or more.
minimumSize 3 real Minimal number of expressions in a method to apply this analysis.
Short name Functions/TooMuchIndented
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.599. Trailing Comma In Calls

The last argument may be left empty.

This feature was introduced in PHP 7.3.

<?php

// VCS friendly call
// PHP 7.3 and more recent
foo(1,
    2,
    3,
   );

// backward compatible call
// All PHP versions
foo(1,
    2,
    3
   );

?>

See also PHP RFC: Allow a trailing comma in function calls.

Short name Php/TrailingComma
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Severity Minor
Time To Fix Quick (30 mins)

9.600. Trait Not Found

A unknown trait is mentioned in the use expression.

The used traits all exist, but in the configuration block, some unmentioned trait is called.

Be aware that the traits used in any configuration block may originate in any use expression. PHP will check the configuration block at instantiation only, and after compiling : at that moment, it will know all the used traits across the class.

<?php
class x  {
    // c is not a used trait
    use a, b { c::d insteadof e;}

    // e is a used trait, even if is not in the use above.
    use e;
}
?>

See also Traits.

9.600.1. Suggestions

  • Switch the name of the trait to an existing and used trait
  • Drop the expression that rely on the non-existent trait
Short name Traits/TraitNotFound
Rulesets Analyze, LintButWontExec
Severity Minor
Time To Fix Quick (30 mins)

9.601. Typed Property Usage

Traditionally, PHP properties aren’t typed. Since PHP 7.4, it is possible to type properties, just like arguments.

<?php

class User {
    public int $id;
    public string $name;

    public function __construct(int $id, string $name) {
        $this->id = $id;
        $this->name = $name;
    }
}
?>

See also Typed Properties 2.0.

9.601.1. Suggestions

Short name Php/TypedPropertyUsage
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP73, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version 7.4+
Severity Minor
Time To Fix Quick (30 mins)

9.602. Typehint Must Be Returned

When using a typehint for a method, it is compulsory to use a at least one return in the method’s body. This is true for nullable typehint too : return alone won’t be sufficient.

<?php

// The function returns a value (here, correct object)
function foo() : Bar { return new Bar(); }

// The function should at least, return a value
function foo() : Bar { }

// The function should at least, return a value : Null or an object. Void, here, is not acceptable.
function foo() : ?Bar { return; }

?>

PHP lint this, but won’t execute it.

This analysis doesn’t check if the returned value is compatible with the returned typehint. Only its presence is checked.

See also Return Type Declaration and Type hint in PHP function parameters and return values.

9.602.1. Suggestions

  • Add a return with a valid value
Short name Functions/TypehintMustBeReturned
Rulesets Analyze, LintButWontExec, CI-checks
Severity Major
Time To Fix Quick (30 mins)

9.603. Typehinted References

Typehinted arguments have no need for references. Since they are only an object, they are already a reference.

In fact, adding the & on the argument definition may lead to error like Only variables should be passed by reference.

This applies to the object type hint, but not the the others, such as int or bool.

<?php
    // a class
    class X {
        public $a = 3;
    }

    // typehinted reference
    //function foo(object &$x) works too
    function foo(X &$x) {
        $x->a = 1;

        return $x;
    }

    // Send an object
    $y = foo(new X);

    // This prints 1;
    print $y->a;
?>

See also Passing by reference and Objects and references.

9.603.1. Suggestions

  • Remove reference for typehinted arguments, unless the typehint is a scalar typehint.
Short name Functions/TypehintedReferences
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Precision High

9.604. Unbinding Closures

Never drop $this, once a closure was created in a non-static method.

From the PHP wiki : Currently it is possible to unbind the $this variable from a closure that originally had one by using $closure->bindTo(null). Due to the removal of static calls to non-static methods in PHP 8, we now have a guarantee that $this always exists inside non-static methods. We would like to have a similar guarantee that $this always exists for non-static closures declared inside non-static methods. Otherwise, we will end up imposing an unnecessary performance penalty either on $this accesses in general, or $this accesses inside such closures.

<?php

class x {
    private $a = 3;

    function foo() {
        return function () { echo $this->a; };
    }
}

$closure = (new x)->foo();

// $this was expected, and it is not anymore
$closure->bindTo(null);

$closure->bindTo(new x);

?>

Calling bindTo() with a valid object is still valid.

See also Unbinding `$this from non-static closures <https://wiki.php.net/rfc/deprecations_php_7_4#unbinding_this_from_non-static_closures>`_.

9.604.1. Suggestions

  • Create a static closure, which doesn’t rely on $this at all
  • Remove the call to bindTo(null).
Short name Functions/UnbindingClosures
Rulesets CompatibilityPHP74
Severity Minor
Time To Fix Quick (30 mins)

9.605. Uncaught Exceptions

The following exceptions are thrown in the code, but are never caught.

<?php

// This exception is throw, but not caught. It will lead to a fatal error.
if ($message = check_for_error()) {
    throw new My\Exception($message);
}

// This exception is throw, and caught.
try {
    if ($message = check_for_error()) {
        throw new My\Exception($message);
    }
} catch (\Exception $e) {
    doSomething();
}

?>

Either they will lead to a Fatal Error, or they have to be caught by an including application. This is a valid behavior for libraries, but is not for a final application.

See also Structuring PHP Exceptions.

9.605.1. Suggestions

  • Catch all the exceptions you throw
Short name Exceptions/UncaughtExceptions
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.606. Unchecked Resources

Resources are created, but never checked before being used. This is not safe.

Always check that resources are correctly created before using them.

<?php

// always check that the resource is created correctly
$fp = fopen($d,'r');
if ($fp === false) {
    throw new Exception('File not found');
}
$firstLine = fread($fp);

// This directory is not checked : the path may not exist and return false
$uncheckedDir = opendir($pathToDir);
while(readdir($uncheckedDir)) {
    // do something()
}

// This file is not checked : the path may not exist or be unreadable and return false
$fp = fopen($pathToFile);
while($line = freads($fp)) {
    $text .= $line;
}

// unsafe one-liner : using bzclose on an unchecked resource
bzclose(bzopen('file'));

?>

See also resources.

Short name Structures/UncheckedResources
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Slow (1 hour)
ClearPHP no-unchecked-resources

9.607. Unconditional Break In Loop

An unconditional break in a loop creates dead code. Since the break is directly in the body of the loop, it is always executed, creating a strange loop that can only run once.

Here, break may also be a return, a goto or a continue. They all branch out of the loop. Such statement are valid, but should be moderated with a condition.

<?php

// return in loop should be in
function summAll($array) {
    $sum = 0;

    foreach($array as $a) {
        // Stop at the first error
        if (is_string($a)) {
            return $sum;
        }
        $sum += $a;
    }

    return $sum;
}

// foreach loop used to collect first element in array
function getFirst($array) {
    foreach($array as $a) {
        return $a;
    }
}

?>

9.607.1. Suggestions

  • Remove the loop and call the content of the loop once.
Short name Structures/UnconditionLoopBreak
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples LiveZilla, MediaWiki

9.608. Undefined ::class

\:\:class doesn’t check if a corresponding class exists.

\:\:class must be checked with a call to class_exists(). Otherwise, it may lead to a Class 'foo' not found or even silent dead code : this happens also with Catch and instanceof commands with undefined classes. PHP doesn’t raise an error in that case.

<?php

class foo() {}

// prints foo
echo foo::class;

// prints bar though bar doesn't exist.
echo bar::class;

?>

See also Class Constants.

Short name Classes/UndefinedStaticclass
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)

9.609. Undefined Caught Exceptions

Those are exceptions that are caught in the code, but are not defined in the application.

They may be externally defined, such as in core PHP, extensions or libraries. Make sure those exceptions are useful to your application : otherwise, they are dead code.

<?php

try {
    library_function($some, $args);

} catch (LibraryException $e) {
    // This exception is not defined, and probably belongs to Library
    print Library failed\n;

} catch (OtherLibraryException $e) {
    // This exception is not defined, and probably do not belongs to this code
    print Library failed\n;

} catch (\Exception $e) {
    // This exception is a PHP standard exception
    print Something went wrong, but not at Libary level\n;
}

?>

9.609.1. Suggestions

  • Remove the catch clause, as it is dead code
  • Make sure the exception is thrown by the underlying code
Short name Exceptions/CaughtButNotThrown
Rulesets Dead code

9.610. Undefined Class Constants

Class constants that are used, but never defined. This should yield a fatal error upon execution, but no feedback at compile level.

<?php

class foo {
    const A = 1;
    define('B', 2);
}

// here, C is not defined in the code and is reported
echo foo::A.foo::B.foo::C;

?>

9.610.1. Suggestions

  • Fix the name of the constant
  • Add the constant to the current class or one of its parent
  • Update the constant’s visibility
Short name Classes/UndefinedConstants
Rulesets none
Severity Major
Time To Fix Quick (30 mins)

9.611. Undefined Classes

Those classes are used in the code, but there are no definition for them.

This may happens under normal conditions, if the application makes use of an unsupported extension, that defines extra classes; or if some external libraries, such as PEAR, are not provided during the analysis.

<?php

// FPDF is a classic PDF class, that is usually omitted by Exakat.
$o = new FPDF();

// Exakat reports undefined classes in instanceof
// PHP ignores them
if ($o instanceof SomeClass) {
    // doSomething();
}

// Classes may be used in typehint too
function foo(TypeHintClass $x) {
    // doSomething();
}

?>
Short name Classes/UndefinedClasses
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)

9.612. Undefined Constant Name

When using the `` syntax for variable, the name used must be a defined constant. It is not a simple string, like ‘x’, it is an actual constant name.

Interestingly, it is possible to use a qualified name within ``, full or partial. PHP will lint such code, and will collect the value of the constant immediately. Since there is no fallback mechanism for fully qualified names, this ends with a Fatal error.

<?php

const x = a;
$a = Hello;

// Display 'Hello'  -> $a -> Hello
echo ;

// Yield a PHP Warning
// Use of undefined constant y - assumed 'y' (this will throw an Error in a future version of PHP)
echo ;

// Yield a PHP Fatal error as PHP first checks that the constant exists
//Undefined constant 'y'
echo ;
?>

9.612.1. Suggestions

  • Define the constant
  • Turn the dynamic syntax into a normal variable syntax
  • Use a fully qualified name (at least one ) to turn this syntax into a Fatal error when the constant is not found. This doesn’t fix the problem, but may make it more obvious during the diagnostic.
Short name Variables/UndefinedConstantName
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.613. Undefined Constants

Constants definition can’t be located.

Those constants are not defined in the code, and will raise errors, or use the fallback mechanism of being treated like a string.

<?php

const A = 1;
define('B', 2);

// here, C is not defined in the code and is reported
echo A.B.C;

?>

It is recommended to define them all, or to avoid using them.

See also Constants.

9.613.1. Suggestions

  • Define the constant
  • Fix the name of the constant
  • Fix the namespace of the constant (FQN or use)
  • Remove the usage of the constant
Short name Constants/UndefinedConstants
Rulesets Analyze, Analyze, CompatibilityPHP72, CI-checks, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Precision Very high

9.614. Undefined Functions

Some functions are called, but not defined in the code. This means that the functions are probably defined in a missing library, or in an extension. If not, this will yield a Fatal error at execution.

<?php

// Undefined function
foo($a);

// valid function, as it belongs to the ext/yaml extension
$parsed = yaml_parse($yaml);

// This function is not defined in the a\b\c namespace, nor in the global namespace
a\b\c\foo();

?>

See also Functions.

9.614.1. Suggestions

  • Fix the name of the function in the code
  • Remove the functioncall in the code
  • Define the function for the code to call it
  • Include the correct library in the code source
Short name Functions/UndefinedFunctions
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Precision High

9.615. Undefined Insteadof

Insteadof tries to replace a method with another, but it doesn’t exists. This happens when the replacing class is refactored, and some of its definition are dropped.

Insteadof may replace a non-existing method with an existing one, but not the contrary.

<?php

trait A {
    function C (){}
}

trait B {
    function C (){}
}

class Talker {
    use A, B {
        B::C insteadof A;
        B::D insteadof A;
    }
}

new Talker();
?>

This error is not linted : it only appears at execution time.

See also Traits.

9.615.1. Suggestions

  • Remove the insteadof expression
  • Fix the original method and replace it with an existing method
Short name Traits/UndefinedInsteadof
Rulesets Analyze, LintButWontExec, CI-checks
Severity Major
Time To Fix Instant (5 mins)

9.616. Undefined Interfaces

Some typehints or instanceof that are relying on undefined interfaces or classes. They will always return false. Any condition based upon them are dead code.

<?php

class var implements undefinedInterface {
    // If undefinedInterface is undefined, this code lints but doesn't run
}

if ($o instanceof undefinedInterface) {
    // This is silent dead code
}

function foo(undefinedInterface $a) {
    // This is dead code
    // it will probably be discovered at execution
}

?>

See also Object interfaces, Type declarations, and Instanceof.

9.616.1. Suggestions

  • Implement the missing interfaces
  • Remove the code governed by the missing interface : the whole method if it is an typehint, the whole if/then if it is a condition.
Short name Interfaces/UndefinedInterfaces
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples xataface

9.617. Undefined Parent

List of properties and methods that are accessed using parent keyword but are not defined in the parent classes.

This may compile but, eventually yields a fatal error during execution.

<?php

class theParent {
    // No bar() method
    // private bar() method is not accessible to theChild
}

class theChild extends theParent {
    function foo() {
        // bar is defined in theChild, but not theParent
        parent::bar();
    }

    function bar() {

    }
}

?>

Note that if the parent is defined using extends someClass but someClass is not available in the tested code, it will not be reported : it may be in composer, another dependency, or just missing.

See also parent <https://www.php.net/manual/en/keyword.`parent.php>`_.

9.617.1. Suggestions

  • Remove the usage of the found method
  • Add a definition for the method in the appropriate parent
  • Fix the name of the method, and replace it with a valid definition
  • Change ‘parent’ with ‘self’ if the method is eventually defined in the current class
  • Change ‘parent’ with another object, if the method has been defined in another class
  • Add the ‘extends’ keyword to the class, to actually have a parent class
Short name Classes/UndefinedParentMP
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.618. Undefined Properties

List of properties that are not explicitly defined in the class, its parents or traits.

<?php

class foo {
    // property definition
    private bar = 2;

    function foofoo() {
        // $this->bar is defined in the class
        // $this->barbar is NOT defined in the class
        return $this->bar + $this->barbar;
    }
}

?>

It is possible to spot unidentified properties by using the PHP’s magic methods __get and __set. Even if the class doesn’t use magic methods, any call to an undefined property will be directed to those methods, and they can be used as a canary, warning that the code is missing a definition.

<?php

trait NoUnefinedProperties {
     function __get($name) {
             assert(false, "Attempt to read the $name property, on the class ".__CLASS__;
     }

     function __set($name, $value) {
             assert(false, "Attempt to read the $name property, on the class ".__CLASS__;
     }
}

?>

See also Properties.

9.618.1. Suggestions

  • Add an explicit property definition, and give it null as a default value : this way, it behaves the same as undefined.
Short name Classes/UndefinedProperty
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-undefined-properties
Examples WordPress, MediaWiki

9.619. Undefined Trait

Those are undefined, traits .

When the using class or trait is instantiated, PHP emits a a fatal error.

<?php

use Composer/Component/someTrait as externalTrait;

trait t {
    function foo() {}
}

// This class uses trait that are all known
class hasOnlyDefinedTrait {
    use t, externalTrait;
}

// This class uses trait that are unknown
class hasUndefinedTrait {
    use unknownTrait, t, externalTrait;
}
?>

Trait which are referenced in a use expression are omitted: they are considered part of code that is probably outside the current code, either omitted or in external component.

9.619.1. Suggestions

  • Define the missing trait
  • Remove usage of the missing trait
Short name Traits/UndefinedTrait
Rulesets Analyze, LintButWontExec, CI-checks
Severity Critical
Time To Fix Quick (30 mins)
Precision High

9.620. Undefined Variable

Variable that is used before any creation.

It is recommended to use a default value for every variable used. When not specified, the default value is set to NULL by PHP.

<?php

// Adapted from the PHP manual
$var = 'Bob';
$Var = 'Joe';
// The following line may emit a warning : Undefined variable: $undefined
echo $var, $Var, $undefined;      // outputs Bob, Joe,


?>

Variable may be created in various ways : assignation, arguments, foreach blind variables, static and global variables.

This analysis doesn’t handle dynamic variables, such as $$x. It also doesn’t handle variables outside a method or function.

See also Variable basics.

9.620.1. Suggestions

  • Remove the expression that is using the undefined variable
  • Fix the variable name
  • Define the variable by assigning a value to it, before using it
Short name Variables/UndefinedVariable
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.621. Undefined static:: Or self::

self and static refer to the current class, or one of its parent. The property or the method may be undefined.

<?php

class x {
    static public function definedStatic() {}
    private definedStatic = 1;

    public function method() {
        self::definedStatic();
        self::undefinedStatic();

        static::definedStatic;
        static::undefinedStatic;
    }
}

?>

See also Late `Static Bindings <https://www.php.net/manual/en/language.oop5.late-static-bindings.php>`_.

9.621.1. Suggestions

  • Define the missing method or property
  • Remove usage of that undefined method or property
  • Fix name to call an actual local structure
Short name Classes/UndefinedStaticMP
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples xataface, SugarCrm

9.622. Unicode Escape Partial

PHP 7 introduces a new escape sequence for strings : u{hex}. It is backward incompatible with previous PHP versions for two reasons :

PHP 7 will recognize en replace those sequences, while PHP 5 keep them intact. PHP 7 will halt on partial Unicode Sequences, as it tries to understand them, but may fail.

<?php

echo \u{1F418}\n;
// PHP 5 displays the same string
// PHP 7 displays : an elephant

echo \u{NOT A UNICODE CODEPOINT}\n;
// PHP 5 displays the same string
// PHP 7 emits a fatal error

?>

Is is recommended to check all those strings, and make sure they will behave correctly in PHP 7.

Short name Php/UnicodeEscapePartial
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Quick (30 mins)

9.623. Unicode Escape Syntax

Usage of the Unicode Escape syntax, with the \u{xxxxx} format, available since PHP 7.0.

<?php

// Produce an elephant icon in PHP 7.0+
echo \u{1F418};

// Produce the raw sequence in PHP 5.0
echo \u{1F418};

?>

See also PHP RFC: Unicode Codepoint Escape Syntax, Code point and Unicode.

Short name Php/UnicodeEscapeSyntax
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and more recent
Severity Major
Time To Fix Slow (1 hour)

9.624. Uninitilized Property

Uninitilized properties are not fully bootstrapped at the end of the constructor.

Properties may be inited at definition time, along with their visibility and type. Some types are not inited at definition time, as any object, so they should be inited during constructor. At the end of the former, all properties shall have a legit value, and be ready for usage.

<?php

class x {
    private $foo = null;
    private $uninited;

    function __construct($arg) {
        $this->foo = $args;

        // $this->uninited is not inited, nor at definition, nor in constructor
        // it will hold null at the beginning of the next method call
    }
}

?>

9.624.1. Suggestions

  • Remove the property, and move it to another class
  • Add an initialisation for this property
Short name Classes/UninitedProperty
Rulesets ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.625. Union Typehint

Union typehints allows the specification of several typehint for the same argument or return value. This is a PHP 8.0 new feature.

Several typehints are specified at the same place as a single one. The different values are separated by a pipe character |, like for exceptions

<?php

// Example from the RFC https://wiki.php.net/rfc/union_types_v2
class Number {
    private int|float $number;

    public function setNumber(int|float $number): void {
        $this->number = $number;
    }

    public function getNumber(): int|float {
        return $this->number;
    }
}
?>

Union types are not compatible with PHP 7 and older.

See also PHP RFC: Union Types 2.0.

9.625.1. Suggestions

Short name Php/Php80UnionTypehint
Rulesets CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP73, CompatibilityPHP74
Php Version 8.0+
Severity Minor
Time To Fix Quick (30 mins)

9.626. Unitialized Properties

Properties that are not initialized in the constructor, nor at definition.

<?php

class X {
    private $i1 = 1, $i2;
    protected $u1, $u2;

    function __construct() {
        $this->i2 = 1 + $this->u2;
    }

    function m() {
        echo $this->i1, $this->i2, $this->u1, $this->u2;
    }
}
?>

With the above class, when m() is accessed right after instantiation, there will be a missing property. Using default values at property definition, or setting default values in the constructor ensures that the created object is consistent.

9.626.1. Suggestions

  • Add an explicit initialization for each property.
Short name Classes/UnitializedProperties
Rulesets Suggestions, Top10
Severity Major
Time To Fix Quick (30 mins)
Examples SPIP

9.627. Unknown Parameter Name

The name of the parameter doesn’t belong to the method signature.

<?php

// All good
foo(a:1, b:2, c:3);

// A is not a parameter name, it should be a
foo(A:1, b:2, c:3);

function foo($a, $b, $c) {}
?>

See also Named Arguments.

9.627.1. Suggestions

  • Fix the name of the parameter and use a valid one
  • Remove the parameter name, and revert to positional notation
Short name Functions/UnknownParameterName
Rulesets Analyze, CI-checks
Php Version 8.0+
Severity Minor
Time To Fix Quick (30 mins)

9.628. Unknown Pcre2 Option

PCRE2 supports different options, compared to PCRE1. PCRE2 was adopted with PHP 7.3.

The S modifier : it used to tell PCRE to spend more time studying the regex, so as to be faster at execution. This is now the default behavior, and may be dropped from the regex.

The X modifier : X is still existing with PCRE2, though it is now the default for PCRE2, and not for PHP as time of writing. In particular, Any backslash in a pattern that is followed by a letter that has no special meaning causes an error, thus reserving these combinations for future expansion. ``. It is recommended to avoid using useless sequence \s in regex to get ready for that change. All the following letters ``gijkmoqyFIJMOTY . Note that clLpPuU are valid PRCE sequences, and are probably failing for other reasons.

<?php

// \y has no meaning. With X option, this leads to a regex compilation error, and a failed test.
preg_match('/ye\y/', $string);
preg_match('/ye\y/X', $string);

?>

See also Pattern Modifiers and PHP RFC: PCRE2 migration.

Short name Php/UnknownPcre2Option
Rulesets Analyze, CompatibilityPHP73
Severity Minor
Time To Fix Instant (5 mins)

9.629. Unkown Regex Options

Regex support in PHP accepts the following list of options : eimsuxADJSUX.

All other letter used as option are not supported : depending on the situation, they may be ignored or raise an error.

<?php

// all options are available
if (preg_match('/\d+/isA', $string, $results)) { }

// p and h are not regex options, p is double
if (preg_match('/\d+/php', $string, $results)) { }

?>

See also Pattern Modifiers

Short name Structures/UnknownPregOption
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)

9.630. Unpacking Inside Arrays

The variadic operator is now available inside arrays. Until PHP 7.4, it is not possible to use the variadic operator, or ... inside arrays.

The workaround is to use array_merge(), after checking that arrays are not empty.

<?php

$a = ['a', 'b', 'c'];
$b = ['d', 'e', 'f'];

// PHP 7.4
$c = [...$a, ...$b];

// PHP 7.3 and older
$c = array_merge($a, $b);

?>
See also Spread Operator in Array Expression and
PHP 5.6 and the Splat Operator .

9.630.1. Suggestions

  • Replace array_merge() with ....
Short name Php/UnpackingInsideArrays
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP71, CompatibilityPHP72, CompatibilityPHP73, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version 7.4+
Severity Minor
Time To Fix Quick (30 mins)

9.631. Unpreprocessed Values

Preprocessing values is the preparation of values before PHP executes the code.

There is no macro language in PHP, that prepares the code before compilation, bringing some comfort and short syntax. Most of the time, one uses PHP itself to preprocess data.

For example :

<?php
    $days_en = 'monday,tuesday,wednesday,thursday,friday,saturday,sunday';
    $days_zh = '星期-,星期二,星期三,星期四,星期五,星期六,星期日';

    $days = explode(',', $lang === 'en' ? $days_en : $days_zh);
?>

could be written

<?php
    if ($lang === 'en') {
        $days = ['monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday', 'sunday'];
    } else {
        $days = ['星期-', '星期二', '星期三', '星期四', '星期五', '星期六', '星期日'];
    }
?>

and avoid preprocessing the string into an array first.

Preprocessing could be done anytime the script includes all the needed values to process the expression.

9.631.1. Suggestions

  • Preprocess the values and hardcode them in PHP. Do not use PHP to calculate something at the last moment.
  • Use already processed values, or cache to avoid calculating the value each hit.
  • Create a class that export the data in the right format for every situation, including the developer’s comfort.
Short name Structures/Unpreprocessed
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP always-preprocess
Examples Zurmo, Piwigo

9.632. Unreachable Class Constant

Class constants may be unreachable due to visibility configuration.

Since PHP 7.1, class constants support visibility. Their usage may be restricted to the current class, or private, to classes that extends or are extended by the current class, or protected. They may also be public, just like it was before.

<?php

class Foo{
    private const PRIVATE = 1;
            const PUBLIC = 3;
}

// PHP 7.1- and older
echo Foo::PUBLIC;

// This is not accessible
echo Foo::PRIVATE;

?>

See also Class Constant and PHP RFC: Support Class Constant Visibility.

9.632.1. Suggestions

  • Make the class constant protected, when the call to the constant is inside a related class.
  • Create another constant, that may be accessible
  • Make the class constant public
Short name Classes/UnreachableConstant
Rulesets ClassReview
Severity Major
Time To Fix Slow (1 hour)

9.633. Unreachable Code

Code may be unreachable, because other instructions prevent its reaching.

For example, it be located after throw, return, exit() <https://www.php.net/`exit>`_, die() <https://www.php.net/`die>`_, goto, break or continue : this way, it cannot be reached, as the previous instruction will divert the engine to another part of the code.

<?php

function foo() {
    $a++;
    return $a;
    $b++;      // $b++ can't be reached;
}

function bar() {
    if ($a) {
        return $a;
    } else {
        return $b;
    }
    $b++;      // $b++ can't be reached;
}

foreach($a as $b) {
    $c += $b;
    if ($c > 10) {
        continue 1;
    } else {
        $c--;
        continue;
    }
    $d += $e;   // this can't be reached
}

$a = 1;
goto B;
class foo {}    // Definitions are accessible, but not functioncalls
B:
echo $a;

?>

This is dead code, that may be removed.

9.633.1. Suggestions

  • Remove the unreachable code
  • Remove the blocking expression, and let the code execute
Short name Structures/UnreachableCode
Rulesets Dead code, Suggestions
Severity Major
Time To Fix Instant (5 mins)
ClearPHP no-dead-code

9.634. Unresolved Catch

Catch clauses do not check for Exception existence.

Catch clauses check that the emitted expression is of the requested Class, but if that class doesn’t exist in the code, the catch clause is always false. This is dead code.

<?php

try {
    // doSomething()
} catch {TypoedExxeption $e) { // Do not exist Exception
    // Fix this exception
} catch {Stdclass $e) {        // Exists, but is not an exception
    // Fix this exception
} catch {Exception $e) {        // Actual and effective catch
    // Fix this exception
}
?>

9.634.1. Suggestions

  • Fix the name of the exception
  • Remove the catch clause
  • Add a use expression with a valid name
  • Create/import the missing exception
Short name Classes/UnresolvedCatch
Rulesets Dead code
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-unresolved-catch

9.635. Unresolved Classes

The following classes are instantiated in the code, but their definition couldn’t be found.

<?php

class Foo extends Bar {
    private function foobar() {
        // here, parent is not resolved, as Bar is not defined in the code.
        return parent::$prop;
    }
}

?>

9.635.1. Suggestions

  • Check for namespaces and aliases and make sure they are correctly configured.
Short name Classes/UnresolvedClasses
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)

9.636. Unresolved Instanceof

The instanceof operator doesn’t confirm if the compared class exists.

It checks if an variable is of a specific class. However, if the referenced class doesn’t exist, because of a bug, a missed inclusion or a typo, the operator always fails, without a warning.

<?php

namespace X {
    class C {}

    // This is OK, as C is defined in X
    if ($o instanceof C) { }

    // This is not OK, as C is not defined in global
    // instanceof respects namespaces and use expressions
    if ($o instanceof \C) { }

    // This is not OK, as undefinedClass
    if ($o instanceof undefinedClass) { }

    // This is not OK, as $class is now a full namespace. It actually refers to \c, which doesn't exist
    $class = 'C';
    if ($o instanceof $class) { }
}
?>

Make sure the following classes are well defined.

See also Instanceof.

9.636.1. Suggestions

  • Remove the call to instanceof and all its dependencies.
  • Fix the class name and use a class existing in the project.
Short name Classes/UnresolvedInstanceof
Rulesets Analyze, Dead code, Top10
Severity Major
Time To Fix Instant (5 mins)
ClearPHP no-unresolved-instanceof
Examples WordPress

9.637. Unresolved Use

The following use instructions cannot be resolved to a class or a namespace. They should be dropped or fixed.

<?php

namespace A {
    // class B is defined
    class B {}
    // class C is not defined
}

namespace X/Y {

    use A/B;  // This use is valid
    use A/C;  // This use point to nothing.

    new B();
    new C();
}

?>

Use expression are options for the current namespace.

See also Using namespaces: Aliasing/Importing.

9.637.1. Suggestions

  • Remove the use expression
  • Fix the use expression
Short name Namespaces/UnresolvedUse
Rulesets Analyze
Severity Major
Time To Fix Slow (1 hour)
ClearPHP no-unresolved-use

9.638. Unserialize Second Arg

Since PHP 7, unserialize() function has a second argument that limits the classes that may be unserialized. In case of a breach, this is limiting the classes accessible from unserialize().

One way to exploit unserialize, is to make PHP unserialized the data to an available class, may be one that may be auto-loaded.

<?php

// safe unserialization : only the expected class will be extracted
$serialized = 'O:7:dbClass:0:{}';
$var = unserialize($serialized, ['dbClass']);
$var->connect();

// unsafe unserialization : $var may be of any type that was in the serialized string
// although, here, this is working well.
$serialized = 'O:7:dbClass:0:{}';
$var = unserialize($serialized);
$var->connect();

// unsafe unserialization : $var is not of the expected type.
// and, here, this will lead to disaster.
$serialized = 'O:10:debugClass:0:{}';
$var = unserialize($serialized);
$var->connect();

?>

See also unserialize(), Securely Implementing (De)Serialization in PHP, and Remote code execution via PHP [Unserialize].

9.638.1. Suggestions

  • Add a list of class as second argument of any call to unserialize(). This is valid for PHP 7.0 and later.
Short name Security/UnserializeSecondArg
Rulesets Security
Php Version With PHP 7.0 and more recent
Severity Critical
Time To Fix Quick (30 mins)
Examples Piwigo, LiveZilla

9.639. Unset In Foreach

Unset applied to the variables of a foreach loop are useless. Those variables are copies and not the actual value. Even if the value is a reference, unsetting it has no effect on the original array : the only effect may be indirect, on elements inside an array, or on properties inside an object.

<?php

// When unset is useless
$array = [1, 2, 3];
foreach($array as $a) {
    unset($a);
}

print_r($array); // still [1, 2, 3]

foreach($array as $b => &$a) {
    unset($a);
}

print_r($array); // still [1, 2, 3]

// When unset is useful
$array = [ [ 'c' => 1] ]; // Array in array
foreach($array as &$a) {
    unset(&$a['c']);
}

print_r($array); // now [ ['c' => null] ]

?>

See also foreach.

9.639.1. Suggestions

  • Drop the unset
Short name Structures/UnsetInForeach
Rulesets Dead code, Analyze
Severity Major
Time To Fix Quick (30 mins)

9.640. Unsupported Types With Operators

Arrays, resources and objects are generally not accepted with unary and binary operators.

The operators are +, -, *, /, **, %, <<, >>, &, |, ^, ~, ++ and .

<?php

var_dump([] % [42]);
// int(0) in PHP 7.x
// TypeError in PHP 8.0 +

// Also impossible usage : index are string or int
$a = [];
$b = $c[$a];

?>

In PHP 8.0, the rules have been made stricter and more consistent.

The only valid operator is +, combined with arrays in both operands. Other situation will throw TypeError.

See also Stricter type checks for arithmetic/bitwise operators and TypeError.

9.640.1. Suggestions

  • Do not use those values with those operators
  • Use a condition to skip this awkward situation
  • Add an extra step to turn this value into a valid type
Short name Structures/UnsupportedTypesWithOperators
Rulesets Analyze, CompatibilityPHP80
Php Version 7.4-
Severity Minor
Time To Fix Quick (30 mins)
Precision Medium

9.641. Unthrown Exception

These are exceptions that are defined in the code but never thrown.

<?php

//This exception is defined but never used in the code.
class myUnusedException extends \Exception {}

//This exception is defined and used in the code.
class myUsedException extends \Exception {}

throw new myUsedException('I was called');

?>

See also Exceptions.

Short name Exceptions/Unthrown
Rulesets Analyze, Dead code
Severity Minor
Time To Fix Quick (30 mins)
ClearPHP no-unthrown-exceptions

9.642. Unused Arguments

Those arguments are not used in the method or function.

Unused arguments should be removed in functions : they are just dead code.

Unused argument may have to stay in methods, as the signature is actually defined in the parent class.

<?php

// $unused is in the signature, but not used.
function foo($unused, $b, $c) {
    return $b + $c;
}
?>

9.642.1. Suggestions

  • Drop the argument from the signature
  • Actually use that argument in the body of the method
Short name Functions/UnusedArguments
Rulesets Analyze
Severity Major
Time To Fix Quick (30 mins)
Examples ThinkPHP, phpMyAdmin

9.643. Unused Class Constant

The class constant is unused. Consider removing it.

<?php

class foo {
    public const UNUSED = 1; // No mention in the code

    private const USED = 2;  // used constant

    function bar() {
        echo self::USED;
    }
}

?>

9.643.1. Suggestions

  • Remove the class constant
  • Use the class constant
Short name Classes/UnusedConstant
Rulesets Analyze, ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.644. Unused Classes

The following classes are never explicitly used in the code.

Note that this may be valid in case the current code is a library or framework, since it defines classes that are used by other (unprovided) codes. Also, this analyzer may find classes that are, in fact, dynamically loaded.

<?php

class unusedClasss {}
class usedClass {}

$y = new usedClass();

?>
Short name Classes/UnusedClass
Rulesets Dead code, Analyze
Severity Major
Time To Fix Quick (30 mins)

9.645. Unused Constants

Those constants are defined in the code but never used. Defining unused constants slow down the application, as they are executed and stored in PHP hashtables.

<?php

// const-defined constant
const USED_CONSTANT  = 0;
const UNUSED_CONSTANT = 1 + USED_CONSTANT;

// define-defined constant
define('ANOTHER_UNUSED_CONSTANT', 3);

?>

It is recommended to comment them out, and only define them when it is necessary.

9.645.1. Suggestions

  • Make use of the constant
  • Remove the constant
Short name Constants/UnusedConstants
Rulesets Dead code
Severity Minor
Time To Fix Instant (5 mins)

9.646. Unused Functions

The functions below are unused. They look like dead code.

Recursive functions, level 1, are detected : they are only reported when a call from outside the function is made. Recursive functions calls of higher level (A calls B calls A) are not handled.

<?php

function used() {}
// The 'unused' function is defined but never called
function unused() {}

// The 'used' function is called at least once
used();

?>

9.646.1. Suggestions

  • Use the function in the code
  • Remove the functions from the code
Short name Functions/UnusedFunctions
Rulesets Dead code
Severity Minor
Time To Fix Quick (30 mins)
Examples Woocommerce, Piwigo

9.647. Unused Global

A global keyword is used in a method, yet the variable is not actually used. This makes PHP import values for nothing, or may create interference

<?php
    function foo() {
        global bar;

        return 1;
    }
?>

9.647.1. Suggestions

  • Remove the global declaration
  • Remove the global variable altogether
Short name Structures/UnusedGlobal
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples Dolphin

9.648. Unused Inherited Variable In Closure

Some closures forgot to make usage of inherited variables.

Closure have two separate set of incoming variables : the arguments (between parenthesis) and the inherited variables, in the ‘use’ clause. Inherited variables are extracted from the local environment at creation time, and keep their value until execution.

The reported closures are requesting some local variables, but do not make any usage of them. They may be considered as dead code.

<?php

// In this closure, $y is forgotten, but $u is used.
$a = function ($y) use ($u) { return $u; };

// In this closure, $u is forgotten
$a = function ($y, $z) use ($u) { return $u; };

?>

See also Anonymous functions.

9.648.1. Suggestions

  • Remove the unused inherited variable
  • Make us of the unused inherited variable
Short name Functions/UnusedInheritedVariable
Rulesets Analyze, Dead code, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples shopware, Mautic

9.649. Unused Interfaces

Those interfaces are defined and never used. They should be removed, as they are dead code.

Interfaces may be use as parent for other interfaces, as typehint (argument, return and property), in instance of.

<?php

interface used {}
interface unused {}

// Used by implementation
class c implements used {}

// Used by extension
interface j implements used {}

$x = new c;

// Used in a instanceof
var_dump($x instanceof used);

// Used in a typehint
function foo(Used $x) {}

?>

9.649.1. Suggestions

  • Remove the interface
  • Actually use the interface
Short name Interfaces/UnusedInterfaces
Rulesets Dead code, Suggestions
Severity Minor
Time To Fix Instant (5 mins)
Examples Tine20

9.650. Unused Label

Some labels have been defined in the code, but they are not used. They may be removed as they are dead code.

<?php

$a = 0;
A:

    ++$a;

    // A loop. A: is used
    if ($a < 10) { goto A; }

// B is never called explicitely. This is useless.
B:

?>

There is no analysis for undefined goto call, as PHP checks that goto has a destination label at compile time :

See also Goto.

9.650.1. Suggestions

  • Remove the unused label
  • Add a goto call to this label
  • Check for spelling mistakes
Short name Structures/UnusedLabel
Rulesets Dead code
Severity Minor
Time To Fix Quick (30 mins)

9.651. Unused Methods

Those methods are never called.

They are probably dead code, unless they are called dynamically.

This analysis omits methods which are in a class that makes dynamical self calls : $this->$m(). That way, any method may be called.

This analysis omits methods which are overwritten by a child class. That way, they are considered to provide a default behavior.

<?php

class foo {
    public function used() {
        $this->used();
    }

    public function unused() {
        $this->used();
    }
}

class bar extends foo {
    public function some() {
        $this->used();
    }
}

$a = new foo();
$a->used();

?>

See also Dead Code: Unused Method.

9.651.1. Suggestions

  • Make use of the method
  • Remove the method
  • Move the method to another class
Short name Classes/UnusedMethods
Rulesets Dead code
Severity Minor
Time To Fix Slow (1 hour)

9.652. Unused Private Methods

Private methods that are not used are dead code.

Private methods are reserved for the defining class. Thus, they must be used with the current class, with $this or self\:\:.

Protected methods, in a standalone class, are also included.

<?php

class Foo {
    // Those methods are used
    private function method() {}
    private static function staticMethod() {}

    // Those methods are not used
    private function unusedMethod() {}
    private static function staticUnusedMethod() {}

    public function bar() {
        self::staticMethod();
        $this->method();
    }
}

?>

This analysis skips classes that makes self dynamic calls, such as $this->$method().

9.652.1. Suggestions

  • Remove the private method, as it is unused
  • Add a call to this private method
  • Change method visibility to make it available to other classes
Short name Classes/UnusedPrivateMethod
Rulesets Dead code
Severity Minor
Time To Fix Quick (30 mins)

9.653. Unused Private Properties

Unused static properties should be removed.

Unused private properties are dead code. They are usually leftovers of development or refactorisation : they used to have a mission, but are now left.

Being private, those properties are only accessible to the current class or trait. As such, validating the

<?php

class foo {
    // This is a used property (see bar method)
    private $used = 1;

    // This is an unused property
    private $unused = 2;

    function bar($a) {
        $this->used += $a;

        return $this->used;
    }
}

?>

9.653.1. Suggestions

  • Remove the property altogether
  • Check if the property wasn’t forgotten in the rest of the class
  • Check if the property is correctly named
  • Change the visibility to protected or public : may be a visibility refactoring was too harsh
Short name Classes/UnusedPrivateProperty
Rulesets Dead code
Severity Minor
Time To Fix Quick (30 mins)
Examples OpenEMR, phpadsnew

9.654. Unused Protected Methods

The following protected methods are unused in children class. As such, they may be considered for being private.

Methods reported by this analysis are not used by children, yet they are protected.

<?php

class Foo {
    // This method is not used
    protected function unusedBar() {}
    protected function usedInFoo() {}
    protected function usedInFooFoo() {}

    public function bar2() {
        // some code
        $this->usedInFoo();
    }
}

class FooFoo extends Foo {
    protected function bar() {}

    public function bar2() {
        // some code
        $this->usedInFooFoo();
    }
}

class someOtherClass {
    protected function bar() {
        // This is not related to foo.
        $this->unusedbar();
    }
}

?>

No usage of those methods were found.

This analysis is impacted by dynamic method calls.

9.654.1. Suggestions

  • Make use of the protected method in the code
  • Remove the method
Short name Classes/UnusedProtectedMethods
Rulesets Dead code
Severity Major
Time To Fix Slow (1 hour)

9.655. Unused Returned Value

The function called returns a value, which is ignored.

Usually, this is a sign of dead code, or a missed check on the results of the functioncall. At times, it may be a valid call if the function has voluntarily no return value.

It is recommended to add a check on the return value, or remove the call.

<?php

// simplest form
function foo() {
    return 1;
}

foo();

// In case of multiple return, any one that returns something means that return value is meaningful
function bar() {
    if (rand(0, 1)) {
        return 1;
    } else {
        return ;
    }
}

bar();

?>

Note that this analysis ignores functions that return void (same meaning that PHP 7.1 : return ; or no return in the function body).

Short name Functions/UnusedReturnedValue
Rulesets Analyze, Dead code
Severity Minor
Time To Fix Quick (30 mins)

9.656. Unused Trait In Class

A trait has been summoned in a class, but is not used. Traits may be used as a copy/paste of code, bringing a batch of methods and properties to a class. In the current case, the imported trait is never called. As such, it may be removed.

Currently, the analysis covers only traits that are used in the class where they are imported. Also, the properties are not covered yet.

<?php

trait t {
    function foo() { return 1;}
}

// this class imports and uses the trait
class UsingTrait {
    use t;

    function bar() {
        return $this->foo() + 1;
    }
}

// this class imports but doesn't uses the trait
class UsingTrait {
    use t;

    function bar() {
        return 1;
    }
}

?>

There are some sneaky situations, where a trait falls into decay : for example, creating a method in the importing class, with the name of a trait class, will exclude the trait method, as the class method has priority. Other precedence rules may lead to the same effect.

See also Traits.

9.656.1. Suggestions

  • Remove the trait from the class
  • Actually use the trait, at least in the importing class
  • Use conflict resolution to make the trait accessible
Short name Traits/UnusedClassTrait
Rulesets ClassReview
Severity Minor
Time To Fix Quick (30 mins)

9.657. Unused Use

Unused use statements. They may be removed, as they clutter the code and slows PHP by forcing it to search in this list for nothing.

<?php

use A as B; // Used in a new call.
use Unused; // Never used. May be removed

$a = new B();

?>
Short name Namespaces/UnusedUse
Rulesets Dead code
Severity Major
Time To Fix Instant (5 mins)
ClearPHP no-useless-use

9.658. Unusual Case For PHP Functions

Usually, PHP functions are written all in lower case.

<?php

// All uppercases PHP functions
ECHO STRTOLOWER('This String');

?>
Short name Php/UpperCaseFunction
Rulesets Coding Conventions
Severity Minor
Time To Fix Instant (5 mins)

9.659. Upload Filename Injection

When receiving a file via Upload, it is recommended to store it under a self-generated name. Any storage that uses the original filename, or even a part of it may be vulnerable to injections.

<?php

// Security error ! the $_FILES['upload']['filename'] is provided by the sender.
// 'a.<script>alert(\'a\')</script>'; may lead to a HTML injection.
$extension = substr( strrchr($_FILES['upload']['name'], '.') ,1);
if (!in_array($extension, array('gif', 'jpeg', 'jpg')) {
    // process error
    continue;
}
// Md5 provides a name without special characters
$name = md5($_FILES['upload']['filename']);
if(@move_uploaded_file($_FILES['upload']['tmp_name'], '/var/no-www/upload/'.$name.'.'.$extension)) {
    safeStoring($name.'.'.$extension, $_FILES['upload']['filename']);
}

// Security error ! the $_FILES['upload']['filename'] is provided by the sender.
if(@move_uploaded_file($_FILES['upload']['tmp_name'], $_FILES['upload']['filename'])) {
    safeStoring($_FILES['upload']['filename']);
}

// Security error ! the $_FILES['upload']['filename'] is provided by the sender.
// 'a.<script>alert('a')</script>'; may lead to a HTML injection.
$extension = substr( strrchr($_FILES['upload']['name'], '.') ,1);
$name = md5($_FILES['upload']['filename']);
if(@move_uploaded_file($_FILES['upload']['tmp_name'], $name.'.'.$extension)) {
    safeStoring($name.'.'.$extension, $_FILES['upload']['filename']);
}

?>

It is highly recommended to validate any incoming file, generate a name for it, and store the result in a folder outside the web folder. Also, avoid accepting PHP scripts, if possible.

See also [CVE-2017-6090], CWE-616: Incomplete Identification of Uploaded File Variables, Why File Upload Forms are a Major Security Threat.

9.659.1. Suggestions

  • Validate uploaded filenames
  • Rename files upon storage, and keep the original name in a database
Short name Security/UploadFilenameInjection
Rulesets Security
Severity Major
Time To Fix Instant (5 mins)

9.660. Use === null

It is faster to use === null instead of is_null().

<?php

// Operator === is fast
if ($a === null) {

}

// Function call is slow
if (is_null($a)) {

}


?>

9.660.1. Suggestions

  • Use === comparison
Short name Php/IsnullVsEqualNull
Rulesets Analyze, php-cs-fixable, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
ClearPHP avoid-those-slow-functions

9.661. Use Array Functions

There are a lot of native PHP functions for arrays. It is often faster to take advantage of them than write a loop.

<?php

$all = implode('-', $s).'-';

// same as above
$all = '';
foreach($array as $s) {
    $all .= $s . '-';
}

?>
See also Array Functions and
No array_merge() In Loops.

9.661.1. Suggestions

  • Remove the loop and use a native PHP function
  • Add more expressions to the loop : batching multiple operations in one loop makes it more interesting than running separates loops.
Short name Structures/UseArrayFunctions
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.662. Use Basename Suffix

basename() will remove extension when it is provided as argument. The second argument will be removed from the name of the file.

<?php

$path = 'phar:///path/to/file.php';

// Don't forget the .
$filename = basename($path, '.php');

// Too much work for this
$filename = substr(basename($path), 0, -4);

?>

Using basename() instead of substr() or else, makes the intention clear.

See also basename.

9.662.1. Suggestions

  • Use basename(), remove more complex code based on substr() or str_replace()
Short name Structures/BasenameSuffix
Rulesets Suggestions
Examples NextCloud, Dolibarr

9.663. Use Case Value

When switch() has branched to the right case, the value of the switched variable is know : it is the case.

This doesn’t work with complex expression cases, nor with default.

<?php

switch($a) {
    case 'a' :
        // $a == 'a';
        echo $a;
        break;

    case 'b' :
        // $a == 'b';
        echo 'b';
        break;
}

?>

9.663.1. Suggestions

  • Use the literal value in the case, to avoid unnecessary computation.
Short name Structures/UseCaseValue
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.664. Use Class Operator

Use \:\:class to hardcode class names, instead of strings.

This is actually faster than strings, which are parsed at execution time, while \:\:class is compiled, making it faster to execute.

It is also capable to handle aliases, making the code easier to maintain.

<?php

namespace foo\bar;

use foo\bar\X as B;

class X {}

$className = '\foo\bar\X';

$className = foo\bar\X::class;

$className = B\X;

$object = new $className;

?>

This is not possible when building the name of the class with concatenation.

This is a micro-optimization. This also helps static analysis, as it gives more information at compile time to analyse.

9.664.1. Suggestions

  • Replace strings by the ::class operator whenever possible
Short name Classes/UseClassOperator
Rulesets Analyze, Performances, CI-checks
Severity Minor
Time To Fix Instant (5 mins)

9.665. Use Const And Functions

Since PHP 5.6 it is possible to import specific functions or constants from other namespaces.

<?php

namespace A {
    const X = 1;
    function foo() { echo __FUNCTION__; }
}

namespace My{
    use function A\foo;
    use constant A\X;

    echo foo(X);
}

?>

See also Using namespaces: Aliasing/Importing.

Short name Namespaces/UseFunctionsConstants
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55
Php Version With PHP 5.6 and more recent
Severity Major
Time To Fix Slow (1 hour)

9.666. Use Constant

The following functioncall have a constant equivalent, that is faster to use than calling the functions.

This applies to the following functions :

<?php

// recommended way
echo PHP_VERSION;

// slow version
echo php_version();

?>

See also PHP why `pi() and M_PI <https://stackoverflow.com/questions/42021176/php-why-pi-and-m-pi>`_.

9.666.1. Suggestions

  • Use the constant version, not the function.
Short name Structures/UseConstant
Rulesets Analyze, php-cs-fixable, CI-checks
Severity Minor
Time To Fix Instant (5 mins)

9.667. Use Constant As Arguments

Some methods and functions are defined to be used with constants as arguments. Those constants are made to be meaningful and readable, keeping the code maintenable. It is recommended to use such constants as soon as they are documented.

<?php

// Turn off all error reporting
// 0 and -1 are accepted
error_reporting(0);

// Report simple running errors
error_reporting(E_ERROR | E_WARNING | E_PARSE);

// The first argument can be one of INPUT_GET, INPUT_POST, INPUT_COOKIE, INPUT_SERVER, or INPUT_ENV.
$search_html = filter_input(INPUT_GET, 'search', FILTER_SANITIZE_SPECIAL_CHARS);

// sort accepts one of SORT_REGULAR, SORT_NUMERIC, SORT_STRING, SORT_LOCALE_STRING, SORT_NATURAL
// SORT_FLAG_CASE may be added, and combined with SORT_STRING or SORT_NATURAL
sort($fruits);

?>

Here is the list of function that use a unique PHP constant as argument :

Here is the list of functions that use a combination of PHP native functions as argument.

9.667.1. Suggestions

  • Use PHP native constants, whenever possible, instead of meaningless literals.
Short name Functions/UseConstantAsArguments
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples Tikiwiki, shopware

9.668. Use Count Recursive

The code could use the recursive version of count.

The second argument of count, when set to COUNT_RECURSIVE, count recursively the elements. It also counts the elements themselves.

<?php

$array = array( array(1,2,3), array(4,5,6));

print (count($array, COUNT_RECURSIVE) - count($array, COUNT_NORMAL));

$count = 0;
foreach($array as $a) {
    $count += count($a);
}
print $count;

?>

See also count.

9.668.1. Suggestions

  • Drop the loop and use the 2nd argument of count()
Short name Structures/UseCountRecursive
Rulesets Suggestions
Severity Minor
Time To Fix Slow (1 hour)
Examples WordPress, PrestaShop

9.669. Use DateTimeImmutable Class

The DateTimeImmutable class is the immutable version of the Datetime class.

While DateTime may be modified ‘in situ’, DateTimeImmutable cannot be modified. Any modification to such an object will return a new and distinct object. This avoid interferences that are hard to track.

<?php
// Example extracted from Derick Rethans' article (link below)

function formatNextMondayFromNow( DateTime $dt )
{
        return $dt->modify( 'next monday' )->format( 'Y-m-d' );
}

$d = new DateTime();                          //2014-02-17
echo formatNextMondayFromNow( $d ), \n;
echo $d->format( 'Y-m-d' ), \n;             //2014-02-17
?>

See also What’s all this ‘immutable date’ stuff, anyway?, DateTimeImmutable, The DateTime class and The DateTimeImmutable class.

9.669.1. Suggestions

  • Always use DateTimeImmutable when manipulating dates.
Short name Php/UseDateTimeImmutable
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.670. Use Instanceof

The instanceof operator is a more precise alternative to is_object(). It is also faster.

instanceof checks for an variable to be of a class or its parents or the interfaces it implements. Once instanceof has been used, the actual attributes available (properties, constants, methods) are known, unlike with is_object().

Last, instanceof may be upgraded to Typehint, by moving it to the method signature.

<?php

class Foo {

    // Don't use is_object
    public function bar($o) {
        if (!is_object($o)) { return false; } // Classic argument check
        return $o->method();
    }

    // use instanceof
    public function bar($o) {
        if ($o instanceof myClass) {  // Now, we know which methods are available
            return $o->method();
        }

        return false; } // Default behavior
    }

    // use of typehinting
    // in case $o is not of the right type, exception is raised automatically
    public function bar(myClass $o) {
        return $o->method();
    }
}

?>

instanceof and is_object() may not be always interchangeable. Consider using isset() on a known property for a simple check on objects. You may also consider is_string(), is_integer() or is_scalar(), in particular instead of !`is_object() <https://www.php.net/is_object>`_.

The instanceof operator is also faster than the is_object() functioncall.

See also Type Operators and is_object.

9.670.1. Suggestions

  • Use instanceof and remove is_object()
  • Create a high level interface to check a whole family of classes, instead of testing them individually
  • Use typehint when possible
  • Avoid mixing scalar types and objects in the same variable
Short name Classes/UseInstanceof
Rulesets none
Severity Major
Time To Fix Quick (30 mins)
Examples TeamPass, Zencart

9.671. Use List With Foreach

Foreach() structures accepts list() as blind key. If the loop-value is an array with a fixed structure, it is possible to extract the values directly into variables with explicit names.

<?php

// Short way to assign variables
// Works on PHP 7.1, where list() accepts keys.
foreach($names as list('first' => $first, 'last' => $last)) {
    doSomething($first, $last);
}

// Short way to assign variables
// Works on all PHP versions with numerically indexed arrays.
foreach($names as list($first, $last)) {
    doSomething($first, $last);
}

// Long way to assign variables
foreach($names as $name) {
    $first = $name['first'];
    $last = $name['last'];

    doSomething($first, $last);
}

?>

See also list and foreach.

9.671.1. Suggestions

  • Use the list keyword (or the short syntax), and simplify the array calls in the loop.
Short name Structures/UseListWithForeach
Rulesets Suggestions, Top10
Severity Minor
Time To Fix Quick (30 mins)
Examples MediaWiki

9.672. Use Lower Case For Parent, Static And Self

The special parent, static and self keywords needed to be lowercase to be usable. This was fixed in PHP 5.5; otherwise, they would yield a ‘PHP Fatal error: Class ‘PARENT’ not found’.

parent, static and self are traditionally written in lowercase only. Mixed case and Upper case are both valid, though.

<?php

class foo {
    const aConstante = 233;

    function method() {
        // Wrong case, error with PHP 5.4.* and older
        echo SELF::aConstante;

        // Always right.
        echo self::aConstante;
    }
}

?>

Until PHP 5.5, non-lowercase version of those keywords are generating a bug.

Short name Php/CaseForPSS
Rulesets CompatibilityPHP54, CompatibilityPHP53
Php Version With PHP 5.5 and older
Severity Minor
Time To Fix Instant (5 mins)

9.673. Use Named Boolean In Argument Definition

Boolean in argument definitions is confusing.

It is recommended to use explicit constant names, instead. They are more readable. They also allow for easy replacement when the code evolve and has to replace those booleans by strings. This works even also with classes, and class constants.

<?php

function flipImage($im, $horizontal = NO_HORIZONTAL_FLIP, $vertical = NO_VERTICAL_FLIP) { }

// with constants
const HORIZONTAL_FLIP = true;
const NO_HORIZONTAL_FLIP = true;
const VERTICAL_FLIP = true;
const NO_VERTICAL_FLIP = true;

rotateImage($im, HORIZONTAL_FLIP, NO_VERTICAL_FLIP);


// without constants
function flipImage($im, $horizontal = false, $vertical = false) { }

rotateImage($im, true, false);

?>

See also Flag Argument, to avoid boolean altogether.

Short name Functions/AvoidBooleanArgument
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples phpMyAdmin, Cleverstyle

9.674. Use Nullable Type

The code uses nullable type, available since PHP 7.1.

Nullable Types are an option to type hint : they allow the passing value to be null, or another type.

According to the authors of the feature : ‘It is common in many programming languages including PHP to allow a variable to be of some type or null. This null often indicates an error or lack of something to return.’

<?php

function foo(?string $a = 'abc') : ?string {
    return $a.b;
}

?>

See also Type declarations and PHP RFC: Nullable Types.

Short name Php/UseNullableType
Rulesets CompatibilityPHP53, CompatibilityPHP70, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.1 and more recent
Severity Major
Time To Fix Quick (30 mins)

9.675. Use PHP Object API

OOP API is the modern version of the PHP API.

When PHP offers the alternative between procedural and OOP api for the same features, it is recommended to use the OOP API.

Often, this least to more compact code, as methods are shorter, and there is no need to bring the resource around. Lots of new extensions are directly written in OOP form too.

OOP / procedural alternatives are available for mysqli, tidy, cairo, finfo, and some others.

<?php
/// OOP version
$mysqli = new mysqli(localhost, my_user, my_password, world);

/* check connection */
if ($mysqli->connect_errno) {
    printf(Connect failed: %s\n, $mysqli->connect_error);
    exit();
}

/* Create table doesn't return a resultset */
if ($mysqli->query(CREATE TEMPORARY TABLE myCity LIKE City) === TRUE) {
    printf(Table myCity successfully created.\n);
}

/* Select queries return a resultset */
if ($result = $mysqli->query(SELECT Name FROM City LIMIT 10)) {
    printf(Select returned %d rows.\n, $result->num_rows);

    /* free result set */
    $result->close();
}
?>
<?php
/// Procedural version
$link = mysqli_connect(localhost, my_user, my_password, world);

/* check connection */
if (mysqli_connect_errno()) {
    printf(Connect failed: %s\n, mysqli_connect_error());
    exit();
}

/* Create table doesn't return a resultset */
if (mysqli_query($link, CREATE TEMPORARY TABLE myCity LIKE City) === TRUE) {
    printf(Table myCity successfully created.\n);
}

?>

9.675.1. Suggestions

  • Use the object API
Short name Php/UseObjectApi
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Slow (1 hour)
ClearPHP use-object-api
Examples WordPress, PrestaShop, SugarCrm

9.676. Use PHP7 Encapsed Strings

PHP 7 has optimized the handling of double-quoted strings. In particular, double-quoted strings are much less memory hungry than classic concatenations.

PHP allocates memory at the end of the double-quoted string, making only one call to the allocator. On the other hand, concatenations are allocated each time they include dynamic content, leading to higher memory consumption.

<?php

$bar = 'bar';

/* PHP 7 optimized this */
$a = "foo and $bar";

/* This is PHP 5 code (aka, don't use it) */
$a = 'foo and ' . $bar;

// Constants can't be used with double quotes
$a = 'foo and ' . __DIR__;
$a = foo and __DIR__; // __DIR__ is not interpolated

?>

Concatenations are still needed with constants, static constants, magic constants, functions, static properties or static methods.

See also PHP 7 performance improvements (3/5): Encapsed strings optimization.

Short name Performances/PHP7EncapsedStrings
Rulesets Performances

9.677. Use Pathinfo

Use pathinfo() function instead of string manipulations.

pathinfo() is more efficient and readable and string functions.

<?php

$filename = '/path/to/file.php';

// With pathinfo();
$details = pathinfo($filename);
print $details['extension'];  // also capture php

// With string functions (other solutions possible)
$ext = substr($filename, - strpos(strreverse($filename), '.')); // Capture php

?>

When the path contains UTF-8 characters, pathinfo() may strip them. There, string functions are necessary.

9.677.1. Suggestions

  • Use pathinfo() and its second argument
Short name Php/UsePathinfo
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples SuiteCrm

9.678. Use Positive Condition

Whenever possible, use a positive condition.

Positive conditions are easier to understand, and lead to less understanding problems. Negative conditions are not reported when else is not present.

<?php

// This is a positive condition
if ($a == 'b') {
    doSomething();
} else {
    doSomethingElse();
}

if (!empty($a)) {
    doSomething();
} else {
    doSomethingElse();
}

// This is a negative condition
if ($a == 'b') {
    doSomethingElse();
} else {
    doSomething();
}

// No need to force $a == 'b' with empty else
if ($a != 'b') {
    doSomethingElse();
}


?>

9.678.1. Suggestions

  • Invert the code in the if branches, and the condition
Short name Structures/UsePositiveCondition
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples SPIP, ExpressionEngine

9.679. Use System Tmp

It is recommended to avoid hardcoding the temporary file. It is better to rely on the system’s temporary folder, which is accessible with sys_get_temp_dir().

<?php

// Where the tmp is :
file_put_contents(sys_get_temp_dir().'/tempFile.txt', $content);


// Avoid hard-coding tmp folder :
// On Linux-like systems
file_put_contents('/tmp/tempFile.txt', $content);

// On Windows systems
file_put_contents('C:\WINDOWS\TEMP\tempFile.txt', $content);

?>

See also PHP: When is /tmp not /tmp?.

9.679.1. Suggestions

  • Do not hardcode the temporary file, use the system’s
Short name Structures/UseSystemTmp
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Slow (1 hour)

9.680. Use The Blind Var

When in a loop, it is faster to rely on the blind var, rather than the original source.

When the key is referenced in the foreach loop, it is faster to use the available container to access a value for reading.

Note that it is also faster to use the value with a reference to handle the writings.

<?php

// Reaching $source[$key] via $value is faster
foreach($source as $key => $value) {
    $coordinates = array('x' => $value[0],
                         'y' => $value[1]);
}

// Reaching $source[$key] via $source is slow
foreach($source as $key => $value) {
    $coordinates = array('x' => $source[$key][0],
                         'y' => $source[$key][1]);
}

?>

9.680.1. Suggestions

  • Use the blind var
Short name Performances/UseBlindVar
Rulesets Performances
Severity Minor
Time To Fix Instant (5 mins)

9.681. Use Url Query Functions

PHP features several functions dedicated to processing URL’s query string.

Those functions include extra checks : for example, http_build_query() adds urlencode() call on the values, and allow for choosing the separator and the Query string format.

<?php
$data = array(
    'foo' => 'bar',
    'baz' => 'boom',
    'cow' => 'milk',
    'php' => 'hypertext processor'
);

// safe and efficient way to build a query string
echo http_build_query($data, '', '&') . PHP_EOL;

// slow way to produce a query string
foreach($data as $name => &$value) {
    $value = $name.'='.$value;
}
echo implode('&', $data) . PHP_EOL;

?>

9.681.1. Suggestions

Short name Structures/UseUrlQueryFunctions
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.682. Use With Fully Qualified Name

Use statement doesn’t require a fully qualified name.

PHP manual recommends not to use fully qualified name (starting with ) when using the ‘use’ statement : they are “the leading backslash is unnecessary and not recommended, as import names must be fully qualified, and are not processed relative to the current namespace”.

<?php

// Recommended way to write a use statement.
use  A\B\C\D as E;

// No need to use the initial \
use \A\B\C\D as F;

?>

9.682.1. Suggestions

  • Remove the initial in use expressions.
Short name Namespaces/UseWithFullyQualifiedNS
Rulesets Analyze, Coding Conventions
Severity Minor
Time To Fix Slow (1 hour)

9.683. Use array_slice()

Array_slice is de equivalent of substr() for arrays.

array_splice() is also possible, to remove a portion of array inside the array, not at the ends. This has no equivalent for strings.

<?php

$array = range(0, 9);

// Extract the 5 first elements
print_r(array_slice($array, 0, 5));

// Extract the 4 last elements
print_r(array_slice($array, -4));

// Extract the 2 central elements : 4 and 5
print_r(array_splice($array, 4, 2));

// slow way to remove the last elementst of an array
for($i = 0; $i < 4) {
    array_pop($array);
}

?>

See also array_slice and array_splice.

9.683.1. Suggestions

Short name Performances/UseArraySlice
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.684. Use const

The const keyword may be used to define constant, just like the define() function.

When defining a constant, it is recommended to use ‘const’ when the features of the constant are not dynamical (name or value are known at compile time). This way, constant will be defined at compile time, and not at execution time.

<?php
  //Do
  const A = 1;
  // Don't
  define('A', 1);

?>

define() function is useful when the constant is not known at compile time, or when case sensitivity is necessary.

<?php
  // Read $a in database or config file
  define('A', $a);

  // Read $a in database or config file
  define('B', 1, true);
  echo b;
?>

See also Syntax.

9.684.1. Suggestions

  • Use const instead of define()
Short name Constants/ConstRecommended
Rulesets Analyze, Coding Conventions, Top10, CI-checks
Severity Minor
Time To Fix Slow (1 hour)
Examples phpMyAdmin, Piwigo

9.685. Use is_countable

is_countable() checks if a variables holds a value that can be counted. It is recommended to use it before calling count().

is_countable() accepts arrays and object whose class implements countable.

<?php

function foo($arg) {
    if (!is_countable($arg)) {
        // $arg cannot be passed to count()
        return 0
    }
    return count($arg);
}

function bar($arg) {
    if (!is_array($arg) and !$x instanceof \Countable) {
        // $arg cannot be passed to count()
        return 0
    }

    return count($arg);
}

?>

See also PHP RFC: is_countable.

9.685.1. Suggestions

  • Use is_countable()
  • Create a compatibility function that replaces is_countable() until the code is ready for PHP 7.3
Short name Php/CouldUseIsCountable
Rulesets Suggestions
Php Version With PHP 7.3 and more recent

9.686. Use json_decode() Options

json_decode() returns objects by default, unless the second argument is set to TRUE or JSON_OBJECT_AS_ARRAY. Then, it returns arrays.

Avoid casting the returned value from json_decode(), and use the second argument to directly set the correct type.

<?php

$json = '{a:b}';

// Good syntax
$array = json_decode($json, JSON_OBJECT_AS_ARRAY);

// GoToo much work
$array = (array) json_decode($json);

?>

Note that all objects will be turned into arrays, recursively. If you’re expecting an array of objects, don’t use the JSON_OBJECT_AS_ARRAY constant, and change your JSON code.

Note that JSON_OBJECT_AS_ARRAY is the only constant : there is no defined constant to explicitly ask for an object as returned value.

See also json_decode.

9.686.1. Suggestions

  • Use the correct second argument of json_decode() : JSON_OBJECT_AS_ARRAY
Short name Structures/JsonWithOption
Rulesets Suggestions
Severity Major
Time To Fix Quick (30 mins)

9.687. Use password_hash()

password_hash() and password_check() are a better choice to replace the use of crypt() to check password.

PHP 5.5 introduced these functions.

<?php

$password = 'rasmuslerdorf';
$hash = '$2y$10$YCFsG6elYca568hBi2pZ0.3LDL5wjgxct1N8w/oLR/jfHsiQwCqTS';

// The cost parameter can change over time as hardware improves
$options = array('cost' => 11);

// Verify stored hash against plain-text password
if (password_verify($password, $hash)) {
    // Check if a newer hashing algorithm is available
    // or the cost has changed
    if (password_needs_rehash($hash, PASSWORD_DEFAULT, $options)) {
        // If so, create a new hash, and replace the old one
        $newHash = password_hash($password, PASSWORD_DEFAULT, $options);
    }

    // Log user in
}
?>

See also Password hashing.

Short name Php/Password55
Rulesets CompatibilityPHP55
Php Version With PHP 5.5 and more recent
Severity Major
Time To Fix Slow (1 hour)

9.688. Use pathinfo() Arguments

pathinfo() has a second argument to select only useful data.

It is twice faster to get only one element from pathinfo() than get the four of them, and use only one.

This analysis reports pathinfo() usage, without second argument, where only one or two indices are used, after the call.

<?php

// This could use only PATHINFO_BASENAME
function foo_db() {
    $a = pathinfo($file2);
    return $a['basename'];
}

// This could be 2 calls, with PATHINFO_BASENAME and PATHINFO_DIRNAME.
function foo_de() {
    $a = pathinfo($file3);
    return $a['dirname'].'/'.$a['basename'];
}

// This is OK : 3 calls to pathinfo() is slower than array access.
function foo_deb() {
    $a = pathinfo($file4);
    return  $a['dirname'].'/'.$a['filename'].'.'.$a['extension'];
}

?>

Depending on the situation, the functions dirname() and basename() may also be used. They are even faster, when only fetching those data.

See also list.

9.688.1. Suggestions

  • Use PHP native function pathinfo() and its arguments
Short name Php/UsePathinfoArgs
Rulesets Performances
Severity Minor
Time To Fix Quick (30 mins)
Examples Zend-Config, ThinkPHP

9.689. Use random_int()

rand() and mt_rand() should be replaced with random_int().

At worse, rand() should be replaced with mt_rand(), which is a drop-in replacement and srand() by mt_srand().

random_int() replaces rand(), and has no seeding function like srand().

Other sources of entropy that should be replaced by random_int() : microtime(), uniqid(), time(). Those a often combined with hashing functions and mixed with other sources of entropy, such as a salt.

<?php

// Avoid using this
$random = rand(0, 10);

// Drop-in replacement
$random = mt_rand(0, 10);

// Even better but different :
// valid with PHP 7.0+
try {
    $random = random_int(0, 10);
} catch (\Exception $e) {
    // process case of not enoug random values
}

// This is also a source of entropy, based on srand()
// random_int() is a drop-in replacement here
$a = sha256(uniqid());

?>

Since PHP 7, random_int() along with random_bytes(), provides cryptographically secure pseudo-random bytes, which are good to be used when security is involved. openssl_random_pseudo_bytes() may be used when the OpenSSL extension is available.

See also CSPRNG and OpenSSL.

9.689.1. Suggestions

  • Use random_bytes() and randon_int(). At least, use them as a base for random data, and then add extra prefix and suffix, and a hash call on top.
Short name Php/BetterRand
Rulesets Analyze, Security, CompatibilityPHP71, CI-checks
Severity Major
Time To Fix Instant (5 mins)
Examples Thelia, FuelCMS

9.690. Use session_start() Options

It is possible to set the session’s option at session_start() call, skipping the usage of session_option().

This way, session’s options are set in one call, saving several hits.

This is available since PHP 7.0. It is recommended to set those values in the php.ini file, whenever possible.

<?php

// PHP 7.0
session_start(['session.name' => 'mySession',
               'session.cookie_httponly' => 1,
               'session.gc_maxlifetime' => 60 * 60);

// PHP 5.6- old way
ini_set ('session.name', 'mySession');
ini_set(session.cookie_httponly, 1);
ini_set('session.gc_maxlifetime', 60 * 60);
session_start();

?>

9.690.1. Suggestions

  • Use session_start() with array arguments
Short name Php/UseSessionStartOptions
Rulesets Suggestions
Php Version With PHP 7.0 and more recent
Examples WordPress

9.691. Used Once Property

Property used once in their defining class.

Properties used in one method only may be used several times, and read only. This may be a class constant. Such properties are meant to be overwritten by an extending class, and that’s possible with class constants.

Setting properties with default values is a good way to avoid littering the code with literal values, and provide a single point of update (by extension, or by hardcoding) for all those situations. A constant is definitely better suited for this task.

<?php

class foo {
    private $defaultCols = '*';
    cont DEFAULT_COLUMNS = '*';

    // $this->defaultCols holds a default value. Should be a constant.
    function bar($table, $cols) {
        // This is necessary to activate usage of default values
        if (empty($cols)) {
            $cols = $this->defaultCols;
        }
        $res = $this->query('SELECT '.$cols.' FROM '.$table);
        // ....
    }

    // Upgraded version of bar, with default values
    function bar2($table, $cols = self::DEFAULT_COLUMNS) {
        $res = $this->query('SELECT '.$cols.' FROM '.$table);
        // .....
    }
}

?>

9.691.1. Suggestions

  • Remove the property, as it is probably not unused
  • Add another usage of the property where it is useful
Short name Classes/UsedOnceProperty
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Precision High

9.692. Used Once Variables

This is the list of used once variables.

<?php

// The variables below never appear again in the code
$writtenOnce = 1;

foo($readOnce);

?>

Such variables are useless. Variables must be used at least twice : once for writing, once for reading, at least. It is recommended to remove them.

In special situations, variables may be used once :

  • PHP predefined variables, as they are already initialized. They are omitted in this analyze.
  • Interface function’s arguments, since the function has no body; They are omitted in this analyze.
  • Dynamically created variables ($$x, ${$this->y} or also using extract), as they are runtime values and can’t be determined at static code time. They are reported for manual review.
  • Dynamically included files will provide in-scope extra variables.

The current analyzer count variables at the application level, and not at a method scope level.

9.692.1. Suggestions

  • Remove the variable
  • Fix the name of variable
  • Use the variable a second time, at least
Short name Variables/VariableUsedOnce
Rulesets Analyze, Top10
Severity Minor
Time To Fix Instant (5 mins)
Examples shopware, Vanilla

9.693. Used Once Variables (In Scope)

This is the list of used once variables, scope by scope. Those variables are used once in a function, a method, a class or a namespace. In any case, this means the variable is read or written, while it should be used at least twice.

<?php

function foo() {
    // The variables below never appear twice, inside foo()
    $writtenOnce = 1;

    foo($readOnce);
    // They do appear again in other functions, or in global space.
}

function bar() {
    $writtenOnce = 1;
    foo($readOnce);
}

?>

9.693.1. Suggestions

  • Remove the variable
  • Fix the name of variable
  • Use the variable a second time in the current scope, at least
Short name Variables/VariableUsedOnceByContext
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Precision High
Examples shopware

9.694. Useless Abstract Class

Those classes are marked ‘abstract’ and they are never extended. This way, they won’t be instantiated nor used.

Abstract classes that have only static methods are omitted here : one usage of such classes are Utilities classes, which only offer static methods.

<?php

// Never extended class : this is useless
abstract class foo {}

// Extended class
abstract class bar {
    public function barbar() {}
}

class bar2 extends bar {}

// Utility class : omitted here
abstract class bar {
    public static function barbar() {}
}

?>

9.694.1. Suggestions

  • Drop the abstract keyword
  • Actually add an abstract keyword
Short name Classes/UselessAbstract
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)

9.695. Useless Alias

It is not possible to declare an alias of a method with the same name.

PHP reports that Trait method f has not been applied, because there are collisions with other trait methods on x, which is a way to say that the alias will be in conflict with the method name.

When the method is the only one bearing a name, and being imported, there is no need to alias it. When the method is imported in several traits, the keyword insteadof is available to solve the conflict.

<?php

trait t {
    function h() {}
}

class x {
    use t {
        // This is possible
        t::f as g;

        // This is not possible, as the alias is in conflict with itself
        // alias are case insensitive
        t::f as f;
    }
}

?>

This code lints but doesn’t execute.

See also Conflict resolution.

9.695.1. Suggestions

  • Remove the alias
  • Fix the alias or the origin method name
  • Switch to insteadof, and avoid as keyword
Short name Traits/UselessAlias
Rulesets Analyze, LintButWontExec, CI-checks
Severity Major
Time To Fix Instant (5 mins)

9.696. Useless Brackets

Standalone brackets have no use. Brackets are used to delimit a block of code, and are used by control statements. They may also be used to protect variables in strings.

Standalone brackets may be a left over of an old instruction, or a misunderstanding of the alternative syntax.

<?php

// The following brackets are useless : they are a leftover from an older instruction
// if (DEBUG)
{
    $a = 1;
}

// Here, the extra brackets are useless
for($a = 2; $a < 5; $a++) : {
    $b++;
} endfor;

?>

9.696.1. Suggestions

  • Remove the brackets
  • Restore the flow-control operation that was there and removed
  • Move the block into a method or function, and call it
Short name Structures/UselessBrackets
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples ChurchCRM, Piwigo

9.697. Useless Casting

There is no need to overcast returned values.

<?php

// trim always returns a string : cast is useless
$a = (string) trim($b);

// strpos doesn't always returns an integer : cast is useful
$a = (boolean) strpos($b, $c);

// comparison don't need casting, nor parenthesis
$c = (bool) ($b > 2);

?>

See also Type juggling.

9.697.1. Suggestions

  • Remove the type cast
Short name Structures/UselessCasting
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples FuelCMS, ThinkPHP

9.698. Useless Catch

Catch clause should handle the exception with some work.

Among the task of a catch clause : log the exception, clean any mess that was introduced, fail graciously.

<?php

function foo($a) {
    try {
        $b = doSomething($a);
    } catch (Throwable $e) {
        // No log of the exception : no one knows it happened.

        // return immediately ?
        return false;
    }

    $b->complete();

    return $b;
}

?>

See also Exceptions and Best practices for PHP exception handling.

9.698.1. Suggestions

  • Add a log call to the catch block
  • Handle correctly the exception
Short name Exceptions/UselessCatch
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Slow (1 hour)
Examples Zurmo, PrestaShop

9.699. Useless Check

There is no need to check the size of an array content before using foreach. Foreach() applies a test on the source, and skips the loop if no element is found.

<?php

// Checking for type is good.
if (is_array($array)) {
    foreach($array as $a) {
        doSomething($a);
    }
}

// Foreach on empty arrays doesn't start. Checking is useless
if (!empty($array)) {
    foreach($array as $a) {
        doSomething($a);
    }
}

?>

This analysis checks for conditions with sizeof() and count(). Conditions with isset() and empty() are omitted : they also check for the variable existence, and thus, offer extra coverage.

See also foreach.

9.699.1. Suggestions

  • Drop the condition and the check
  • Turn the condition into isset(), empty() and is_array()
Short name Structures/UselessCheck
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples Magento, Phinx

9.700. Useless Constructor

Class constructor that have empty bodies are useless. They may be removed.

<?php

class X {
    function __construct() {
        // Do nothing
    }
}

class Y extends X {
    // Useful constructor, as it prevents usage of the parent
    function __construct() {
        // Do nothing
    }
}

?>
Short name Classes/UselessConstructor
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)

9.701. Useless Default Argument

One of the argument has a default value, and this default value is never used. Every time the method is called, the argument is provided explicitly, rendering the default value actually useless.

<?php

function goo($a, $b = 3) {
    // do something here
}

// foo is called 3 times, and sometimes, $b is not provided.
goo(1,2);
goo(1,2);
goo(1);


function foo($a, $b = 3) {
    // do something here
}

// foo is called 3 times, and $b is always provided.
foo(1,2);
foo(1,2);
foo(1,2);
?>

9.701.1. Suggestions

  • Remove the default value
  • Remove the explicit argument in the function call, when it is equal to the default value
Short name Functions/UselessDefault
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)

9.702. Useless Final

When a class is declared final, all of its methods are also final by default.

There is no need to declare them individually final.

<?php

    final class foo {
        // Useless final, as the whole class is final
        final function method() { }
    }

    class bar {
        // Useful final, as the whole class is not final
        final function method() { }
    }

?>

See also Final Keyword, and When to declare final.

Short name Classes/UselessFinal
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
ClearPHP no-useless-final

9.703. Useless Global

Global are useless in two cases. First, on super-globals, which are always globals, like $_GET; secondly, on variables that are not used.

<?php

// $_POST is already a global : it is in fact a global everywhere
global $_POST;

// $unused is useless
function foo() {
    global $used, $unused;

    ++$used;
}

?>

Also, PHP has superglobals, a special team of variables that are always available, whatever the context. They are : $GLOBALS, $_SERVER, $_GET, $_POST, $_FILES, $_COOKIE, $_SESSION, $_REQUEST and $_ENV.

9.703.1. Suggestions

  • Drop the global expression
Short name Structures/UselessGlobal
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples Zencart, HuMo-Gen

9.704. Useless Instructions

Those instructions are useless, or contains useless parts.

For example, an addition whose result is not stored in a variable, or immediately used, does nothing : it is actually performed, and the result is lost. Just plain lost. In fact, PHP might detect it, and optimize it away.

Here the useless instructions that are spotted :

<?php

// Concatenating with an empty string is useless.
$string = 'This part '.$is.' useful but '.$not.'';

// This is a typo, that PHP turns into a constant, then a string, then nothing.
continue;

// Empty string in a concatenation
$a = 'abc' . '';

// Returning expression, whose result is not used (additions, comparisons, properties, closures, new without =, ...)
1 + 2;

// Returning post-incrementation
function foo($a) {
    return $a++;
}

// array_replace() with only one argument
$replaced = array_replace($array);
// array_replace() is OK with ...
$replaced = array_replace(...$array);

// @ operator on source array, in foreach, or when assigning literals
$array = @array(1,2,3);

// Multiple comparisons in a for loop : only the last is actually used.
for($i = 0; $j = 0; $j < 10, $i < 20; ++$j, ++$i) {
    print $i.' '.$j.PHP_EOL;
}

// Counting the keys and counting the array is the same.
$c = count(array_keys($array))

//array_keys already provides an array with only unique values, as they were keys in a previous array
$d = array_unique(array_keys($file['messages']))

// No need for assignation inside the ternary operator
$closeQuote = $openQuote[3] === "'" ? substr($openQuote, 4, -2) : $closeQuote = substr($openQuote, 3);

?>

9.704.1. Suggestions

  • Remove the extra semi-colon
  • Remove the useless instruction
  • Assign this expression to a variable and make use of it
Short name Structures/UselessInstruction
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Precision High
ClearPHP no-useless-instruction

9.705. Useless Interfaces

The interfaces below are defined and are implemented by some classes.

However, they are never used to enforce an object’s class in the code, using instanceof or in a typehint. As they are currently used, those interfaces may be removed without change in behavior.

<?php
    // only defined interface but never enforced
    interface i {};
    class c implements i {}
?>

Interfaces should be used in Typehint or with the instanceof operator.

<?php
    interface i {};

    function foo(i $arg) {
        // Now, $arg is always an 'i'
    }

    function bar($arg) {
        if (!($arg instanceof i)) {
            // Now, $arg is always an 'i'
        }
    }
?>

9.705.1. Suggestions

  • Use the interface with instanceof, or a typehint
  • Drop the interface altogether : both definition and implements keyword
Short name Interfaces/UselessInterfaces
Rulesets Analyze, ClassReview, Typechecks
Severity Minor
Time To Fix Quick (30 mins)
ClearPHP no-useless-interfaces
Examples Woocommerce

9.706. Useless Parenthesis

Situations where parenthesis are not necessary, and may be removed.

Parenthesis group several elements together, and allows for a more readable expression. They are used with logical and mathematical expressions. They are necessary when the precedence of the operators are not the intended execution order : for example, when an addition must be performed before the multiplication.

Sometimes, the parenthesis provide the same execution order than the default order : they are deemed useless.

<?php

    if ( ($condition) ) {}
    while( ($condition) ) {}
    do $a++; while ( ($condition) );

    switch ( ($a) ) {}
    $y = (1);
    ($y) == (1);

    f(($x));

    // = has precedence over ==
    ($a = $b) == $c;

    ($a++);

    // No need for parenthesis in default values
    function foo($c = ( 1 + 2) ) {}
?>

See also Operators Precedence.

9.706.1. Suggestions

  • Remove useless parenthesis, unless they are important for readability.
Short name Structures/UselessParenthesis
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples Mautic, Woocommerce

9.707. Useless Referenced Argument

The argument has a reference, but is only used for reading.

This is probably a development artefact that was forgotten. It is better to remove it.

This analysis also applies to foreach() loops, that declare the blind variable as reference, then use the variable as an object, accessing properties and methods. When a variable contains an object, there is no need to declare a reference : it is a reference automatically.

<?php

function foo($a, &$b, &$c) {
    // $c is passed by reference, but only read. The reference is useless.
    $b = $c + $a;
    // The reference is useful for $b
}

foreach ($array as &$element) {
    $element->method();
}

?>

See also Objects and references.

9.707.1. Suggestions

  • Remove the useless & from the argument
  • Make an actual use of the argument before the end of the method
Short name Functions/UselessReferenceArgument
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
Examples Woocommerce, Magento

9.708. Useless Return

The spotted functions or methods have a return statement, but this statement is useless. This is the case for constructor and destructors, whose return value are ignored or inaccessible.

When return is void, and the last element in a function, it is also useless.

<?php

class foo {
    function __construct() {
        // return is not used by PHP
        return 2;
    }
}

function bar(&$a) {
    $a++;
    // The last return, when empty, is useless
    return;
}

?>

9.708.1. Suggestions

  • Remove the return expression. Keep any other calculation.
Short name Functions/UselessReturn
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)
Precision Very high
Examples ThinkPHP, Vanilla

9.709. Useless Switch

This switch has only one case. It may very well be replaced by a ifthen structure.

<?php
switch($a) {
    case 1:
        doSomething();
        break;
}

// Same as

if ($a == 1) {
    doSomething();
}
?>

9.709.1. Suggestions

  • Turn the switch into a if/then for better readability
  • Add other cases to the switch, making it adapted to the situation
Short name Structures/UselessSwitch
Rulesets Analyze
Severity Major
Time To Fix Instant (5 mins)
Examples Phpdocumentor, Dolphin

9.710. Useless Type Check

With typehint, some checks on the arguments are now handled by the type system.

In particular, a type hinted argument can’t be null, unless it is explicitly nullable, or has a null value as default.

<?php

// The test on null is useless, it will never happen
function foo(A $a) {
    if (is_null($a)) {
        // do something
    }
}

// Either nullable ? is too much, either the default null is
function barbar(?A $a = null) {
}

// The test on null is useful, the default value null allows it
function bar(A $a = null) {
    if ($a === null) {
        // do something
    }
}


?>

See also Type Declarations.

9.710.1. Suggestions

  • Remove the nullable typehint
  • Remove the null default value
  • Remove tests on null
Short name Functions/UselessTypeCheck
Rulesets Dead code
Severity Minor
Time To Fix Quick (30 mins)

9.711. Useless Typehint

__get and __set magic methods won’t use any typehint. The name of the magic property is always cast to string.

__call()

<?php

class x {
    // typehint is set and ignored
    function __set(float $name, string $value) {
        $this->$name = $value;
    }

    // typehint is set and ignored
    function __get(integer $name) {
        $this->$name = $value;
    }

    // typehint is checked by PHP 8.0 linting
    // typehint is enforced by PHP 7.x
    function __call(integer $name) {
        $this->$name = $value;
    }
}

$o = new x;
$b = array();
// Property will be called 'Array'
$o->{$b} = 2;

// type of $m is check at calling time. It must be string.
$o->{$m}();

?>

See also __set.

9.711.1. Suggestions

  • Use string for the $name parameter
  • Use no typehint for the $name parameter
Short name Classes/UselessTypehint
Rulesets Suggestions, ClassReview
Severity Minor
Time To Fix Quick (30 mins)
Precision Very high

9.712. Useless Unset

There are situations where trying to remove a variable is actually useless.

PHP ignores any command that tries to unset a global variable, a static variable, or a blind variable from a foreach loop.

This is different from the garbage collector, which is run on its own schedule. It is also different from an explicit unset, aimed at freeing memory early : those are useful.

<?php

function foo($a) {
    // unsetting arguments is useless
    unset($a);

    global $b;
    // unsetting global variable has no effect
    unset($b);

    static $c;
    // unsetting static variable has no effect
    unset($c);

    foreach($d as &$e){
        // unsetting a blind variable is useless
        (unset) $e;
    }
    // Unsetting a blind variable AFTER the loop is good.
    unset($e);
}

?>

See also unset.

9.712.1. Suggestions

  • Remove the unset
  • Set the variable to null : the effect is the same on memory, but the variable keeps its existence.
  • Omit unsetting variables, and wait for the end of the scope. That way, PHP free memory en mass.
Short name Structures/UselessUnset
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
ClearPHP no-useless-unset
Examples Tine20, Typo3

9.713. Uses Default Values

Default values are provided to methods so as to make it convenient to use. However, with new versions, those values may change. For example, in PHP 5.4, htmlentities() switched from Latin1 to UTF-8 default encoding.

<?php

$string = Eu não sou o pão;

echo htmlentities($string);

// PHP 5.3 : Eu n&Atilde;&pound;o sou o p&Atilde;&pound;o
// PHP 5.4 : Eu n&atilde;o sou o p&atilde;o

// Stable across versions
echo htmlentities($string, 'UTF8');

?>

As much as possible, it is recommended to use explicit values in those methods, so as to prevent from being surprise at a future PHP evolution.

This analyzer tend to report a lot of false positives, including usage of count(). Count() indeed has a second argument for recursive counts, and a default value. This may be ignored safely.

9.713.1. Suggestions

  • Mention all arguments, as much as possible
Short name Functions/UsesDefaultArguments
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.714. Using $this Outside A Class

$this is a special variable, that should only be used in a class context.

Until PHP 7.1, $this may be used as an argument in a function or a method, a global, a static : while this is legit, it sounds confusing enough to avoid it.

<?php

function foo($this) {
    echo $this;
}

// A closure can be bound to an object at later time. It is valid usage.
$closure = function ($x) {
    echo $this->foo($x);
}

?>

Starting with PHP 7.1, the PHP engine check thoroughly that $this is used in an appropriate manner, and raise fatal errors in case it isn’t.

Yet, it is possible to find $this outside a class : if the file is included inside a class, then $this will be recognized and validated. If the file is included outside a class context, it will yield a fatal error : Using `$this <https://www.php.net/manual/en/language.oop5.basic.php>`_ when not in object context.

See also Closure::bind and The Basics.

Short name Classes/UsingThisOutsideAClass
Rulesets Analyze, CompatibilityPHP71, LintButWontExec
Php Version With PHP 7.0 and older
Severity Critical
Time To Fix Instant (5 mins)

9.715. Using Deprecated Method

A call to a deprecated method has been spotted. A method is deprecated when it bears a @deprecated parameter in its typehint definition.

Deprecated methods which are not called are not reported.

<?php

// not deprecated method
not_deprecated();

// deprecated method
deprecated();

/**
 * @deprecated since version 2.0.0
 */
function deprecated() {}

function not_deprecated() {}

?>

See also @deprecated.

9.715.1. Suggestions

  • Replace the deprecated call with a stable call
Short name Functions/UsingDeprecated
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.716. Usort Sorting In PHP 7.0

Usort(), uksort() and uasort() behavior has changed in PHP 7. Values that are equals (based on the user-provided method) may be sorted differently than in PHP 5.

If this sorting is important, it is advised to add extra comparison in the user-function and avoid returning 0 (thus, depending on default implementation).

<?php

$a = [ 2, 4, 3, 6];

function noSort($a) { return $a > 5; }

usort($a, 'noSort');
print_r($a);

?>

In PHP 5, the results is ::

Array
(
    [0] => 3
    [1] => 4
    [2] => 2
    [3] => 6
)

in PHP 7, the result is ::

Array
(
    [0] => 2
    [1] => 4
    [2] => 3
    [3] => 6
)
Short name Php/UsortSorting
Rulesets CompatibilityPHP70
Severity Major
Time To Fix Slow (1 hour)

9.717. Var Keyword

Var was used in PHP 4 to mark properties as public. Nowadays, new keywords are available : public, protected, private. Var is equivalent to public.

It is recommended to avoid using var, and explicitly use the new keywords.

<?php

class foo {
    public $bar = 1;
    // Avoid var
    //var $bar = 1;
}

?>

See also Visibility.

9.717.1. Suggestions

  • It is recommended to avoid using var, and explicitly use the new keywords : private, protected, public
Short name Classes/OldStyleVar
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
ClearPHP no-php4-class-syntax
Examples xataface

9.718. Variable Global

Variable global such are valid in PHP 5.6, but no in PHP 7.0. They should be replaced with ${$foo->bar}.

<?php

// Forbidden in PHP 7
global $normalGlobal;

// Forbidden in PHP 7
global $$variable->global ;

// Tolerated in PHP 7
global ${$variable->global};

?>
Short name Structures/VariableGlobal
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and older
Severity Minor
Time To Fix Quick (30 mins)

9.719. Variable Is Not A Condition

Avoid using a lone variable as a condition. It is recommended to use a comparative value, or one of the filtering function, such as isset(), empty().

Using the raw variable as a condition blurs the difference between an undefined variable and an empty value. By using an explicit comparison or validation function, it is easier to understand what the variable stands for.

<?php

if (isset($error)) {
    echo 'Found one error : '.$error!;
}

//
if ($errors) {
    print count($errors).' errors found : '.join('', $errors).PHP_EOL;
    echo 'Not found';
}

?>

Thanks to the PMB team for the inspiration.

9.719.1. Suggestions

  • Make the validation explicit, by using a comparison operator, or one of the validation function.
Short name Structures/NoVariableIsACondition
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.720. Variables With One Letter Names

Variables with one letter name are the shortest name for variables. They also bear very little meaning : what does contain the variable $w ?

Some one-letter variables have meaning : $x and $y for coordinates, $i, $j, $k for blind variables. Others tend to be an easy way to give a name to a variable, without thinking too hard a good name.

<?php

// $a is reported as a one-letter variable
$a = 0;

// $i is considered a false positive.
for($i = 0; $i < 10; ++$i) {
    $a += doSomething($i);
}

?>

See also Using single characters for variable names in loops/exceptions and Single Letter Variable Names Still Considered Harmful.

9.720.1. Suggestions

  • Make the variable more meaningful, with full words
Short name Variables/VariableOneLetter
Rulesets Semantics
Precision Very high

9.721. Weak Typing

The test on a variable is not enough. The variable is checked for null, then used as an object or an array.

<?php

if ($a !== null) {
    echo $a->b;
}

?>

See also From assumptions to assertions.

9.721.1. Suggestions

  • Use instanceof when checking for objects
  • Use is_array() when checking for arrays. Also consider is_string(), is_int(), etc.
  • Use typehint when the variable is an argument
Short name Classes/WeakType
Rulesets Analyze
Severity Minor
Time To Fix Instant (5 mins)
Examples TeamPass

9.722. Weird Array Index

Array index that looks weird. Arrays index may be string or integer, but some strings looks weird.

In particular, strings that include terminal white spaces, often leads to missed values.

<?php

$array = ['a ' => 1, 'b' => 2, 'c' => 3];

// Later in the code

//Notice: Undefined index: a in /Users/famille/Desktop/analyzeG3/test.php on line 8
echo $array['a'];

//Notice: Undefined index: b  in /Users/famille/Desktop/analyzeG3/test.php on line 10
// Note that the space is visible, but easy to miss
echo $array['b '];

// all fine here
echo $array['c'];

?>

Although this is rare error, and often easy to spot, it is also very hard to find when it strikes.

9.722.1. Suggestions

  • Remove white spaces when using strings as array index.
Short name Arrays/WeirdIndex
Rulesets Semantics
Severity Minor
Time To Fix Quick (30 mins)

9.723. While(List() = Each())

This code structure is quite old : it should be replace by the more modern and efficient foreach.

This structure is deprecated since PHP 7.2. It may disappear in the future.

<?php

    while(list($key, $value) = each($array)) {
        doSomethingWith($key) and $value();
    }

    foreach($array as $key => $value) {
        doSomethingWith($key) and $value();
    }
?>

See also PHP RFC: Deprecations for PHP 7.2 : `Each() <https://wiki.php.net/rfc/deprecations_php_7_2#each>`_.

9.723.1. Suggestions

  • Change this loop with foreach
  • Change this loop with an array_* function with a callback
Short name Structures/WhileListEach
Rulesets Analyze, Performances, Suggestions, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples OpenEMR, Dolphin

9.724. Written Only Variables

Those variables are being written, but never read. This way, they are useless and should be removed, or read at some point.

<?php

// $a is used multiple times, but never read
$a = 'a';
$a .= 'b';

$b = 3;
//$b is actually read once
$a .= $b + 3;

?>

9.724.1. Suggestions

  • Check that variables are written AND read in each context
  • Remove variables that are only read
  • Use the variable that are only read
Short name Variables/WrittenOnlyVariable
Rulesets Analyze
Severity Minor
Time To Fix Slow (1 hour)
ClearPHP no-unused-variable
Examples Dolibarr, SuiteCrm

9.725. Wrong Access Style to Property

Use the right syntax when reaching for a property. Static properties use the \:\: operator, and non-static properties use ->.

Mistaking one of the other raise two different reactions from PHP : Access to undeclared `static <https://www.php.net/manual/en/language.oop5.static.php>`_ property is a fatal error, while PHP Notice:  Accessing `static <https://www.php.net/manual/en/language.oop5.static.php>`_ property aa\:\:$a as non `static <https://www.php.net/manual/en/language.oop5.static.php>`_ is a notice.

<?php

class a {
    static public $a = 1;

    function foo() {
        echo self::$a; // right
        echo $this->a; // WRONG
    }
}

class b {
    public $b = 1;

    function foo() {
        echo $this->$b;  // right
        echo b::$b;      // WRONG
    }
}

?>

This analysis reports both static properties with a -> access, and non-static properties with a :: access.

See also Static Keyword <https://www.php.net/manual/en/language.oop5.`static.php>`_.

9.725.1. Suggestions

  • Match the property call with the definition
  • Make the property static
Short name Classes/UndeclaredStaticProperty
Rulesets Analyze, ClassReview, CI-checks
Severity Critical
Time To Fix Quick (30 mins)
Examples HuMo-Gen

9.726. Wrong Argument Type

Checks that the type of the argument is consistent with the type of the called method.

<?php

function foo(int $a) { }

//valid call, with an integer
foo(1);

//invalid call, with a string
foo('asd');

?>

This analysis is valid with PHP 8.0.

9.726.1. Suggestions

  • Always use a valid type when calling methods.
Short name Functions/WrongArgumentType
Rulesets Analyze, Typechecks
Severity Minor
Time To Fix Quick (30 mins)

9.727. Wrong Case Namespaces

Namespaces are case-insentives.

<?php

// Namespaces should share the same case
namespace X {}

namespace x {}

?>

9.727.1. Suggestions

  • Synchronize all names
Short name Namespaces/WrongCase
Rulesets none
Severity Minor
Time To Fix Quick (30 mins)

9.728. Wrong Class Name Case

The spotted classes are used with a different case than their definition. While PHP accepts this, it makes the code harder to read.

It may also be a violation of coding conventions.

<?php

// This use statement has wrong case for origin.
use Foo as X;

// Definition of the class
class foo {}

// Those instantiations have wrong case
new FOO();
new X();

?>

See also PHP class name constant case sensitivity and PSR-11.

9.728.1. Suggestions

  • Match the defined class name with the called name
Short name Classes/WrongCase
Rulesets Coding Conventions, Coding Conventions, Coding Conventions
Severity Minor
Time To Fix Instant (5 mins)
Examples WordPress

9.729. Wrong Function Name Case

The spotted functions are used with a different case than their definition. While PHP accepts this, it makes the code harder to read.

It may also be a violation of coding conventions.

<?php

// Definition of the class
function foo () {}

// Those calls have wrong case
FOO();
\Foo();

// This is valid
foo();

?>

See also PHP class name constant case sensitivity and PSR-11.

9.729.1. Suggestions

  • Match the defined functioncall with the called name
Short name Functions/WrongCase
Rulesets none
Severity Minor
Time To Fix Instant (5 mins)

9.730. Wrong Number Of Arguments

Those functioncalls are made with too many or too few arguments.

When the number arguments is wrong for native functions, PHP emits a warning. When the number arguments is too small for custom functions, PHP raises an exception. When the number arguments is too high for custom functions, PHP ignores the arguments. Such arguments should be handled with the variadic operator, or with func_get_args() family of functions.

<?php

echo strtoupper('This function is', 'ignoring arguments');
//Warning: strtoupper() expects exactly 1 parameter, 2 given in Command line code on line 1

echo strtoupper();
//Warning: strtoupper() expects exactly 1 parameter, 0 given in Command line code on line 1

function foo($argument) {}
echo foo();
//Fatal error: Uncaught ArgumentCountError: Too few arguments to function foo(), 0 passed in /Users/famille/Desktop/analyzeG3/test.php on line 10 and exactly 1 expected in /Users/famille/Desktop/analyzeG3/test.php:3

echo foo('This function is', 'ignoring arguments');

?>

It is recommended to check the signature of the methods, and fix the arguments.

9.730.1. Suggestions

  • Add more arguments to fill the list of compulsory arguments
  • Remove arguments to fit the list of compulsory arguments
  • Use another method or class
Short name Functions/WrongNumberOfArguments
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Precision High
ClearPHP no-missing-argument.md
Examples xataface

9.731. Wrong Optional Parameter

Wrong placement of optional parameters.

PHP parameters are optional when they defined with a default value, like this :

<?php
    function x($arg = 1) {
        // PHP code here
    }
?>

When a function have both compulsory and optional parameters, the compulsory ones should appear first, and the optional should appear last :

<?php
    function x($arg, $arg2 = 2) {
        // PHP code here
    }
?>

PHP solves this problem at runtime, assign values in the same other, but will miss some of the default values and emits warnings.

It is better to put all the optional parameters at the end of the method’s signature.

Optional parameter wrongly placed are now a Notice in PHP 8.0. The only previous case that is allowed in PHP 8.0 and also in this analysis, is when the null value is used as default for typed arguments.

See also Function arguments.

9.731.1. Suggestions

  • Give default values to all but first parameters. Null is a good default value, as PHP will use it if not told otherwise.
  • Remove default values to all but last parameters. That is probably a weak solution.
  • Change the order of the values, so default-valued parameters are at the end. This will probably have impact on the rest of the code, as the API is changing.
Short name Functions/WrongOptionalParameter
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples FuelCMS, Vanilla

9.732. Wrong Parameter Type

The expected parameter is not of the correct type. Check PHP documentation to know which is the right format to be used.

<?php

// substr() shouldn't work on integers.
// the first argument is first converted to string, and it is 123456.
echo substr(123456, 0, 4); // display 1234

// substr() shouldn't work on boolean
// the first argument is first converted to string, and it is 1, and not t
echo substr(true, 0, 1); // displays 1

// substr() works correctly on strings.
echo substr(123456, 0, 4);

?>
Short name Php/InternalParameterType
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples Zencart

9.733. Wrong Range Check

The interval check should use && and not ||.

<?php

//interval correctly checked a is between 2 and 999
if ($a > 1 && $a < 1000) {}

//interval incorrectly checked : a is 2 or more ($a < 1000 is never checked)
if ($a > 1 || $a < 1000) {}

?>

9.733.1. Suggestions

  • Make the interval easy to read and understand
  • Check the truth table for the logical operation
Short name Structures/WrongRange
Rulesets Analyze
Severity Major
Time To Fix Instant (5 mins)
Examples Dolibarr, WordPress

9.734. Wrong Returned Type

The returned value is not compatible with the specified return type.

<?php

// classic error
function bar() : int {
    return 'A';
}

// classic static error
const B = 2;
function bar() : string {
    return B;
}

// undecideable error
function bar($c) : string {
    return $c;
}

// PHP lint this, but won't execute it
function foo() : void {
    // No return at all
}

?>

See also Returning values and Void Return Type.

9.734.1. Suggestions

  • Match the return type with the return value
  • Remove the return expression altogether
  • Add a typecast to the returning expression
Short name Functions/WrongReturnedType
Rulesets Analyze, ClassReview, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.735. Wrong Type For Native PHP Function

This analysis reports calls to a PHP native function with a wrongly typed value.

<?php

// valid calls
echo exp(1);
echo exp(2.5);

// invalid calls
echo exp(1);
echo exp(array(2.5));

// valid call, but invalid math
// -1 is not a valid value for log(), but -1 is a valid type (int) : it is not reported by this analysis.
echo log(-1);
?>

9.735.1. Suggestions

  • Set the code to the valid type, when calling a PHP native function
Short name Php/WrongTypeForNativeFunction
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.736. Wrong Type With Call

This analysis checks that a call to a method uses the right literal values’ types.

Currently, this analysis doesn’t take into account strict_types = 1.

<?php

function foo(string $a) {

}

// wrong type used
foo(1);

// wrong type used
foo("1");

?>

9.736.1. Suggestions

  • Use the right type with all literals
Short name Functions/WrongTypeWithCall
Rulesets Analyze, Typechecks, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Precision Very high

9.737. Wrong Typed Property Default

Property is typed with an incompatible default value type.

Init type might be a new instance, the return of a method call or an interface compatible object.

<?php

class x {
    private A $property;
    private B $incompatible;

    function __construct() {
        // This is compatible
        $this->property = new A();

        // This is incompatible : new B() expected
        $this->incompatible = new C();

    }
}

?>

PHP compiles such code, but won’t execute it, as it detects the incompatibility.

9.737.1. Suggestions

  • Remove the type hint of the property
  • Fix the initialization call
  • Use an interface for typehint
Short name Classes/WrongTypedPropertyInit
Rulesets Analyze, LintButWontExec, ClassReview, CI-checks
Php Version 7.4+
Severity Minor
Time To Fix Quick (30 mins)

9.738. Wrong Typehinted Name

The parameter name doesn’t reflect the typehint used.

There are no restriction on parameter names, except its uniqueness in the signature. Yet, using a scalar typehint as the name for another typehinted value is just misleading.

<?php

function foo(string $array,
             int $int) {
    // doSomething()
}

function bar(array $strings) {
    // doSomething()
}

?>

The comparison relies on exact names : calling an array a list of strings is OK with this analysis.

9.738.1. Suggestions

  • Rename
Short name Functions/WrongTypehintedName
Rulesets Coding Conventions, Semantics
Severity Minor
Time To Fix Quick (30 mins)

9.739. Wrong fopen() Mode

Wrong file opening for fopen().

fopen() has a few modes, as described in the documentation : ‘r’, ‘r+’, for reading; ‘w’, ‘w+’ for writing; ‘a’, ‘a+’ for appending; ‘x’, ‘x+’ for modifying; ‘c’, ‘c+’ for writing and locking, ‘t’ for text files and windows only. An optional ‘b’ may be used to make the fopen() call more portable and binary safe. Another optional ‘t’ may be used to make the fopen() call process automatically text input : this one should be avoided.

<?php

// open the file for reading, in binary mode
$fp = fopen('/tmp/php.txt', 'rb');

// New option e in PHP 7.0.16 and 7.1.2 (beware of compatibility)
$fp = fopen('/tmp/php.txt', 'rbe');

// Unknown option x
$fp = fopen('/tmp/php.txt', 'rbx');

?>

Any other values are not understood by PHP.

9.739.1. Suggestions

  • Check the docs, choose the right opening mode.
Short name Php/FopenMode
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples Tikiwiki, HuMo-Gen

9.740. Yoda Comparison

Yoda comparison is a way to write conditions which places literal values on the left side.

<?php
  if (1 == $a) {
    // Then condition
  }
?>

The objective is to avoid mistaking a comparison to an assignation. If the comparison operator is mistaken, but the literal is on the left, then an error will be triggered, instead of a silent bug.

<?php
    // error in comparison!
    if ($a = 1) {
        // Then condition
    }
?>

See also Yoda Conditions, Yoda Conditions: To Yoda or Not to Yoda.

Short name Structures/YodaComparison
Rulesets Coding Conventions
Severity Minor
Time To Fix Slow (1 hour)

9.741. __DIR__ Then Slash

__DIR__ must be concatenated with a string starting with /.

The magic constant __DIR__ holds the name of the current directory, without final /. When it is used to build path, then the following path fragment must start with /. Otherwise, two directories names will be merged together.

<?php

// __DIR__ = /a/b/c
// $filePath = /a/b/c/g.php

// /a/b/c/d/e/f.txt : correct path
echo __DIR__.'/d/e/f.txt';
echo dirname($filePath).'/d/e/f.txt';

// /a/b/cd/e/f.txt : most probably incorrect path
echo __DIR__.'d/e/f.txt';
echo dirname($filePath).'d/e/f.txt';

?>

9.741.1. Suggestions

  • Add a check on __DIR__, as it may be ‘/’ when run at the root of the server
  • Add a ‘/’ at the beginning of the path after __DIR__.
  • Add a call to realpath() or file_exists(), before accessing the file.
Short name Structures/DirThenSlash
Rulesets Analyze, CI-checks
Severity Major
Time To Fix Instant (5 mins)
Examples Traq

9.742. __debugInfo() Usage

The magic method __debugInfo() provides a custom way to dump an object.

It has been introduced in PHP 5.6. In the previous versions of PHP, this method is ignored and won’t be called when debugging.

<?php

// PHP 5.6 or later
class foo {
    private $bar = 1;
    private $reallyHidden = 2;

    function __debugInfo() {
        return ['bar' => $this->bar,
                'reallyHidden' => 'Secret'];
    }
}

$f = new Foo();
var_dump($f);

/* Displays :
object(foo)#1 (2) {
  [bar]=>
  int(1)
  [reallyHidden]=>
  string(6) Secret
}
*/

?>

See also Magic methods.

Short name Php/debugInfoUsage
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55
Php Version With PHP 5.6 and more recent
Severity Minor
Time To Fix Slow (1 hour)
Examples Dolibarr

9.743. __toString() Throws Exception

Magical method __toString() can’t throw exceptions.

In fact, __toString() may not let an exception pass. If it throw an exception, but must catch it. If an underlying method throws an exception, it must be caught.

<?php

class myString {
    private $string = null;

    public function __construct($string) {
        $this->string = $string;
    }

    public function __toString() {
        // Do not throw exceptions in __toString
        if (!is_string($this->string)) {
            throw new Exception("$this->string is not a string!!");
        }

        return $this->string;
    }
}

?>

A fatal error is displayed, when an exception is not intercepted in the __toString() function.

::

PHP Fatal error: Method myString::__toString() must not throw an exception, caught Exception: ‘Exception message’ in file.php

See also __toString().

9.743.1. Suggestions

  • Remove any usage of exception from __toString() magic method
Short name Structures/toStringThrowsException
Rulesets Analyze
Php Version 7.4-
Severity Major
Time To Fix Quick (30 mins)

9.744. array_key_exists() Speedup

isset() used to be the fastest, but array_key_exists() is. Since PHP 7.4, array_key_exists() has its own opcode, leading to better features and speed.

isset() is faster for all non-empty values, but is limited when the value is NULL or empty : then, array_key_exists() has the good features.

This change makes `array_key_exists() <https://www.php.net/array_key_exists>`_ actually faster than `isset() <https://www.www.php.net/isset>`_ by ~25% (tested with GCC 8, -O3, march=native, mtune=native)..

<?php

$foo = [123 => 456];

// This is sufficient and efficient since PHP 7.4
if (array_search_key($foo[123])) {
    // do something
}

// taking advantages of performances for PHP 7.4 and older
if (isset($foo[123]) || array_search_key($foo[123])) {
    // do something
}

?>

See also Implement ZEND_ARRAY_KEY_EXISTS opcode to speed up `array_key_exists() <https://github.com/php/php-src/pull/3360>`_.

9.744.1. Suggestions

  • Remove the logical test and the isset() call
Short name Performances/ArrayKeyExistsSpeedup
Rulesets Suggestions, Performances
Php Version 7.4+
Severity Minor
Time To Fix Quick (30 mins)

9.745. array_key_exists() Works On Arrays

array_key_exists() requires arrays as second argument. Until PHP 7.4, objects were also allowed, yet it is now deprecated.

<?php

// Valid way to check for key
$array = ['a' => 1];
var_dump(array_key_exists('a', $array))


// Deprecated since PHP 7.4
$object = new Stdclass();
$object->a = 1;
var_dump(array_key_exists('a', $object))

?>
See also array_key_exists() with objects, and
array_key_exists, and.

9.745.1. Suggestions

  • Use the (array) cast to turn the object into an array
  • Use the native PHP function proprety_exists() or isset() on the property to check them.
Short name Php/ArrayKeyExistsWithObjects
Rulesets CompatibilityPHP74, Analyze
Severity Minor
Time To Fix Quick (30 mins)

9.746. array_merge() And Variadic

Always check value in variadic before using it with array_merge() and array_merge_recursive().

Before PHP 7.4, array_merge() and array_merge_recursive() would complain when no argument was provided. As such, using the spread operator on an empty array() would yield no argument, and an error.

<?php

//
$b = array_merge(...$x);



?>

9.746.1. Suggestions

  • Add a check to the spread variable to ensure it is not empty
  • Append an empty array to to the spread variable to ensure it is not empty
Short name Structures/ArrayMergeAndVariadic
Rulesets Analyze
Php Version 7.4-
Severity Minor
Time To Fix Quick (30 mins)

9.747. crypt() Without Salt

PHP requires a salt when calling crypt(). 5.5 and previous versions didn’t require it. Salt is a simple string, that is usually only known by the application.

According to the manual : The salt parameter is optional. However, crypt() creates a weak hash without the salt. PHP 5.6 or later raise an E_NOTICE error without it. Make sure to specify a strong enough salt for better security.

<?php
// Set the password
$password = 'mypassword';

// salted crypt usage (always valid)
$hash = crypt($password, '123salt');

// Get the hash, letting the salt be automatically generated
// This generates a notice after PHP 5.6
$hash = crypt($password);

?>

See also crypt.

9.747.1. Suggestions

  • Always provide the second argument
Short name Structures/CryptWithoutSalt
Rulesets CompatibilityPHP54
Php Version With PHP 5.6 and older
Severity Minor
Time To Fix Instant (5 mins)

9.748. curl_version() Has No Argument

curl_version() used to accept CURLVERSION_NOW as argument. Since PHP 7.4, it is a function without arguments.

<?php

// Compatible syntax
$details = curl_version(CURLVERSION_NOW);

// New PHP 7.4 syntax
$details = curl_version();

?>

See also curl_version.

9.748.1. Suggestions

  • Drop all arguments from curl_version() calls.
Short name Structures/CurlVersionNow
Rulesets CompatibilityPHP74
Severity Minor
Time To Fix Quick (30 mins)

9.749. error_reporting() With Integers

Using named constants with error_reporting is strongly encouraged to ensure compatibility for future versions. As error levels are added, the range of integers increases, so older integer-based error levels will not always behave as expected. (Adapted from the documentation).

<?php

// This is ready for PHP next version
error_reporting(E_ALL & ~E_DEPRECATED & ~E_STRICT & ~E_NOTICE & ~E_WARNING);

// This is not ready for PHP next version
error_reporting(2047);

// -1 and 0 are omitted, as they will be valid even is constants changes.
error_reporting(-1);
error_reporting(0);

?>

See also directive error_reporting and error_reporting.

9.749.1. Suggestions

  • Always use the constant combination when configuring error_reporting or any PHP native function
Short name Structures/ErrorReportingWithInteger
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples SugarCrm

9.750. eval() Without Try

eval() emits a ParseError exception with PHP 7 and later. Catching this exception is the recommended way to handle errors when using the eval() function.

<?php

$code = 'This is no PHP code.';

//PHP 5 style
eval($code);
// Ends up with a Fatal error, at execution time

//PHP 7 style
try {
    eval($code);
} catch (ParseError $e) {
    cleanUpAfterEval();
}

?>

Note that it will catch situations where eval() is provided with code that can’t be used, but it will not catch security problems. Avoid using eval() with incoming data.

9.750.1. Suggestions

  • Always add a try/catch block around eval() call
Short name Structures/EvalWithoutTry
Rulesets Analyze, Security, CI-checks
Php Version With PHP 7.0 and more recent
Severity Critical
Time To Fix Quick (30 mins)
Examples FuelCMS, ExpressionEngine

9.751. ext/apc

Extension Alternative PHP Cache.

The Alternative PHP Cache (APC) is a free and open opcode cache for PHP. Its goal is to provide a free, open, and robust framework for caching and optimizing PHP intermediate code.

This extension is considered unmaintained and dead.

<?php
   $bar = 'BAR';
   apc_add('foo', $bar);
   var_dump(apc_fetch('foo'));
   echo PHP_EOL;

   $bar = 'NEVER GETS SET';
   apc_add('foo', $bar);
   var_dump(apc_fetch('foo'));
   echo PHP_EOL;
?>

See also Alternative PHP Cache.

Short name Extensions/Extapc
Rulesets CompatibilityPHP55
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Slow (1 hour)

9.752. ext/dba

Extension ext/dba.

These functions build the foundation for accessing Berkeley DB style databases.

<?php

$id = dba_open('/tmp/test.db', 'n', 'db2');

if (!$id) {
    echo 'dba_open failed'.PHP_EOL;
    exit;
}

dba_replace('key', 'This is an example!', $id);

if (dba_exists('key', $id)) {
    echo dba_fetch('key', $id);
    dba_delete('key', $id);
}

dba_close($id);
?>

See also Database (dbm-style) Abstraction Layer.

Short name Extensions/Extdba
Rulesets CompatibilityPHP53
Severity Major
Time To Fix Slow (1 hour)

9.753. ext/ereg

Extension ext/ereg.

<?php
if (ereg ('([0-9]{4})-([0-9]{1,2})-([0-9]{1,2})', $date, $regs)) {
    echo $regs[3].'.'.$regs[2].'.'.$regs[1];
} else {
    echo 'Invalid date format: '.$date;
}
?>

See also Ereg.

Short name Extensions/Extereg
Rulesets CompatibilityPHP70
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Quick (30 mins)

9.754. ext/fdf

Extension ext/fdf.

Forms Data Format (FDF) is a format for handling forms within PDF documents.

<?php
$outfdf = fdf_create();
fdf_set_value($outfdf, 'volume', $volume, 0);

fdf_set_file($outfdf, 'http:/testfdf/resultlabel.pdf');
fdf_save($outfdf, 'outtest.fdf');
fdf_close($outfdf);
Header('Content-type: application/vnd.fdf');
$fp = fopen('outtest.fdf', 'r');
fpassthru($fp);
unlink('outtest.fdf');
?>

See also Form Data Format.

Short name Extensions/Extfdf
Rulesets CompatibilityPHP53
Severity Major
Time To Fix Slow (1 hour)

9.755. ext/mcrypt

Extension for mcrypt.

This extension has been deprecated as of PHP 7.1.0 and moved to PECL as of PHP 7.2.0.

This is an interface to the mcrypt library, which supports a wide variety of block algorithms such as DES, TripleDES, Blowfish (default), 3-WAY, SAFER-SK64, SAFER-SK128, TWOFISH, TEA, RC2 and GOST in CBC, OFB, CFB and ECB cipher modes. Additionally, it supports RC6 and IDEA which are considered ‘non-free’. CFB/OFB are 8bit by default.

<?php
    # --- ENCRYPTION ---

    # the key should be random binary, use scrypt, bcrypt or PBKDF2 to
    # convert a string into a key
    # key is specified using hexadecimal
    $key = pack('H*', 'bcb04b7e103a0cd8b54763051cef08bc55abe029fdebae5e1d417e2ffb2a00a3');

    # show key size use either 16, 24 or 32 byte keys for AES-128, 192
    # and 256 respectively
    $key_size =  strlen($key);
    echo 'Key size: ' . $key_size . PHP_EOL;

    $plaintext = 'This string was AES-256 / CBC / ZeroBytePadding encrypted.';

    # create a random IV to use with CBC encoding
    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);

    # creates a cipher text compatible with AES (Rijndael block size = 128)
    # to keep the text confidential
    # only suitable for encoded input that never ends with value 00h
    # (because of default zero padding)
    $ciphertext = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key,
                                 $plaintext, MCRYPT_MODE_CBC, $iv);

    # prepend the IV for it to be available for decryption
    $ciphertext = $iv . $ciphertext;

    # encode the resulting cipher text so it can be represented by a string
    $ciphertext_base64 = base64_encode($ciphertext);

    echo  $ciphertext_base64 . PHP_EOL;

    # === WARNING ===

    # Resulting cipher text has no integrity or authenticity added
    # and is not protected against padding oracle attacks.

    # --- DECRYPTION ---

    $ciphertext_dec = base64_decode($ciphertext_base64);

    # retrieves the IV, iv_size should be created using mcrypt_get_iv_size()
    $iv_dec = substr($ciphertext_dec, 0, $iv_size);

    # retrieves the cipher text (everything except the $iv_size in the front)
    $ciphertext_dec = substr($ciphertext_dec, $iv_size);

    # may remove 00h valued characters from end of plain text
    $plaintext_dec = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key,
                                    $ciphertext_dec, MCRYPT_MODE_CBC, $iv_dec);

    echo  $plaintext_dec . PHP_EOL;
?>

See also extension mcrypt and mcrypt.

Short name Extensions/Extmcrypt
Rulesets CompatibilityPHP71
Severity Major
Time To Fix Slow (1 hour)

9.756. ext/mhash

Extension mhash (obsolete since PHP 5.3.0).

This extension provides functions, intended to work with mhash.

<?php
$input = 'what do ya want for nothing?';
$hash = mhash(MHASH_MD5, $input);
echo 'The hash is ' . bin2hex($hash) . '<br />'.PHP_EOL;
$hash = mhash(MHASH_MD5, $input, 'Jefe');
echo 'The hmac is ' . bin2hex($hash) . '<br />'.PHP_EOL;
?>

See also Extension mhash.

Short name Extensions/Extmhash
Rulesets CompatibilityPHP54
Severity Major
Time To Fix Slow (1 hour)

9.757. ext/ming

Extension ext/ming, to create swf files with PHP.

Ming is an open-source (LGPL) library which allows you to create SWF (‘Flash’) format movies.

<?php
  $s = new SWFShape();
  $f = $s->addFill(0xff, 0, 0);
  $s->setRightFill($f);

  $s->movePenTo(-500, -500);
  $s->drawLineTo(500, -500);
  $s->drawLineTo(500, 500);
  $s->drawLineTo(-500, 500);
  $s->drawLineTo(-500, -500);

  $p = new SWFSprite();
  $i = $p->add($s);
  $i->setDepth(1);
  $p->nextFrame();

  for ($n=0; $n<5; ++$n) {
    $i->rotate(-15);
    $p->nextFrame();
  }

  $m = new SWFMovie();
  $m->setBackground(0xff, 0xff, 0xff);
  $m->setDimension(6000, 4000);

  $i = $m->add($p);
  $i->setDepth(1);
  $i->moveTo(-500,2000);
  $i->setName('box');

  $m->add(new SWFAction('/box.x += 3;'));
  $m->nextFrame();
  $m->add(new SWFAction('gotoFrame(0); play();'));
  $m->nextFrame();

  header('Content-type: application/x-shockwave-flash');
  $m->output();
?>

See also Ming (flash) and Ming.

Short name Extensions/Extming
Rulesets CompatibilityPHP53
Severity Major
Time To Fix Slow (1 hour)

9.758. ext/mysql

Extension for MySQL (Original MySQL API).

This extension is deprecated as of PHP 5.5.0, and has been removed as of PHP 7.0.0. Instead, either the mysqli or PDO_MySQL extension should be used. See also the MySQL API Overview for further help while choosing a MySQL API. .. code-block:: php <?php $result = mysql_query(‘SELECT * WHERE 1=1’); if (!$result) { die(‘Invalid query: ‘ . mysql_error()); } ?> See also Original MySQL API and MySQL.

Short name Extensions/Extmysql
Rulesets CompatibilityPHP55
Php Version With PHP 7.0 and older
Severity Major
Time To Fix Slow (1 hour)

9.759. filter_input() As A Source

The filter_input() and filter_input_array() functions access directly to $_GET. They represent a source for external data just like $_GET, $_POST, etc.

The main feature of filter_input() is that it is already filtered. The main drawback is that FILTER_FLAG_NONE is the none filter, and that default configuration is FILTER_UNSAFE_RAW.

The filter extension keeps access to the incoming data, even after the super globals, such as $_GET, are unset.

<?php

// Removing $_GET
$_GET = [];

// with the default : FILTER_UNSAFE_RAW, this means XSS
echo filter_input(INPUT_GET, 'i');

// Same as above :
echo filter_var(_GET, 'i');

?>

Thanks to Frederic Bouchery for reporting this special case.

See also Data filtering.

9.759.1. Suggestions

  • Use the classic $_GET, $_POST super globals, which are easier to audit.
  • Use your framework’s parameter access.
Short name Security/FilterInputSource
Rulesets Security
Severity Minor
Time To Fix Slow (1 hour)

9.760. fputcsv() In Loops

fputcsv() is slow when called on each row. It actually flushes the data to the disk each time, and that results in a inefficient dump to the disk, each call.

To speed up this process, it is recommended to dump the csv to memory first, then dump the memory to the disk, in larger chunks. Since fputcsv() works only on stream, it is necessary to use a memory stream.

<?php

// Speedy yet memory intensive version
$f = fopen('php://memory', 'w+');
foreach($data_source as $row) {
    // You may configure fputcsv as usual
    fputcsv($f, $row);
}
rewind($f); // Important
$fp = fopen('final.csv', 'w+');
fputs($fp, stream_get_contents($f));
fclose($fp);
fclose($f);

// Slower version
$fp = fopen('final.csv', 'w+');
foreach($data_source as $row) {
    // You may configure fputcsv as usual
    fputcsv($fp, $row);
}
fclose($fp);
?>

The speed improvement is significant on small rows, while it may be less significant on larger rows : with more data in the rows, the file buffer may fill up more efficiently. On small rows, the speed gain is up to 7 times.

9.760.1. Suggestions

  • Use fputcsv() on a memory stream, and flush it on the disk once
Short name Performances/CsvInLoops
Rulesets Performances, Top10
Severity Minor
Time To Fix Quick (30 mins)

9.761. func_get_arg() Modified

func_get_arg() and func_get_args() used to report the calling value of the argument until PHP 7. Since PHP 7, it is reporting the value of the argument at calling time, which may have been modified by a previous instruction.

<?php

function x($a) {
    $a++;
    print func_get_arg(0);
}

x(0);
?>

This code will display 1 in PHP 7, and 0 in PHP 5.

Short name Functions/funcGetArgModified
Rulesets Analyze, CompatibilityPHP70
Severity Major
Time To Fix Quick (30 mins)

9.762. idn_to_ascii() New Default

The default parameter value of idn_to_ascii() and idn_to_utf8() is now INTL_IDNA_VARIANT_UTS46 instead of the deprecated INTL_IDNA_VARIANT_2003.

<?php

echo idn_to_ascii('täst.de');

?>

See also idn_to_ascii, idn_to_utf8 and Unicode IDNA Compatibility Processing.

9.762.1. Suggestions

  • Explicitely add the second parameter to the idn_to_ascii() and idn_to_utf8() functions.
Short name Php/IdnUts46
Rulesets CompatibilityPHP74

9.763. include_once() Usage

include_once() and require_once() functions should be avoided for performances reasons.

<?php

// Including a library.
include 'lib/helpers.inc';

// Including a library, and avoiding double inclusion
include_once 'lib/helpers.inc';

?>

Try using autoload for loading classes, or use include() or require() and make it possible to include several times the same file without errors.

9.763.1. Suggestions

  • Avoid using include_once() whenever possible
  • Use autoload() to load classes, and avoid loading them with include
Short name Structures/OnceUsage
Rulesets Analyze
Severity Minor
Time To Fix Quick (30 mins)
Examples XOOPS, Tikiwiki

9.764. isset() With Constant

Until PHP 7, it was possible to use arrays as constants, but it was not possible to test them with isset.

<?php
const X = [1,2,3];

if (isset(X[4])) {}
?>

This would yield an error : Cannot use `isset() <https://www.www.php.net/isset>`_ on the result of an expression (you can use "null !== expression" instead). This is a backward incompatibility.

Short name Structures/IssetWithConstant
Rulesets CompatibilityPHP53, CompatibilityPHP54, CompatibilityPHP55, CompatibilityPHP56
Php Version With PHP 7.0 and more recent
Severity Major
Time To Fix Instant (5 mins)

9.765. list() May Omit Variables

Simply omit any unused variable in a list() call.

list() is the only PHP function that accepts to have omitted arguments. If the following code makes no usage of a listed variable, just omit it.

<?php
    // No need for '2', so no assignation
    list ($a, , $b) = array(1, 2, 3);
        // works with PHP 7.1 short syntax
         [$a, , $b] = array(1, 2, 3);

    // No need for '2', so no assignation
    list ($a, $c, $b) = array(1, 2, 3);
?>

See also list.

9.765.1. Suggestions

  • Remove the unused variables from the list call
  • When the ignored values are at the beginning or the end of the array, array_slice() may be used to shorten the array.
Short name Structures/ListOmissions
Rulesets Analyze, Suggestions, CI-checks
Severity Minor
Time To Fix Quick (30 mins)
Examples OpenConf, FuelCMS

9.766. mb_strrpos() Third Argument

Passing the encoding as 3rd parameter to mb_strrpos() is deprecated. Instead pass a 0 offset, and encoding as 4th parameter.

<?php

// Finds the position of the last occurrence of of a string in a string, starting at position 10
$extract = mb_strrpos($haystack, $needle, 10, 'utf8');

// This is the old behavior. Here, the offset will be 0, by default
$extract = mb_strrpos($haystack, $needle, 'utf8');
?>

See also mb_strrpos().

9.766.1. Suggestions

Short name Php/Php74mbstrrpos3rdArg
Rulesets CompatibilityPHP74
Severity Minor
Time To Fix Quick (30 mins)

9.767. mcrypt_create_iv() With Default Values

Avoid using mcrypt_create_iv() default values.

mcrypt_create_iv() used to have MCRYPT_DEV_RANDOM as default values, and in PHP 5.6, it now uses MCRYPT_DEV_URANDOM.

<?php
    $size = mcrypt_get_iv_size(MCRYPT_CAST_256, MCRYPT_MODE_CFB);
    // mcrypt_create_iv is missing the second argument
    $iv = mcrypt_create_iv($size);

// Identical to the line below
//    $iv = mcrypt_create_iv($size, MCRYPT_DEV_RANDOM);

?>

If the code doesn’t have a second argument, it relies on the default value. It is recommended to set explicitly the value, so has to avoid problems while migrating.

See also mcrypt_create_iv().

Short name Structures/McryptcreateivWithoutOption
Rulesets CompatibilityPHP70
Php Version With PHP 5.6 and older
Severity Minor
Time To Fix Instant (5 mins)

9.768. move_uploaded_file Instead Of copy

Always use move_uploaded_file() with uploaded files. Avoid using copy or rename with uploaded file.

move_uploaded_file() checks to ensure that the file designated by filename is a valid upload file (meaning that it was uploaded via PHP’s HTTP POST upload mechanism).

<?php

    // $a->file was filled with $_FILES at some point
    move_uploaded_file($a->file['tmp_name'], $target);

    // $a->file was filled with $_FILES at some point
    rename($a->file['tmp_name'], $target);

?>

See also move_uploaded_file and Uploading Files with PHP.

9.768.1. Suggestions

  • Always use move_uploaded_file()
  • Extract the needed information from the file, and leave it for PHP to remove without storage
Short name Security/MoveUploadedFile
Rulesets Security
Severity Major
Time To Fix Quick (30 mins)

9.769. openssl_random_pseudo_byte() Second Argument

openssl_random_pseudo_byte() uses exceptions to signal an error. Since PHP 7.4, there is no need to use the second argument.

On the other hand, it is important to catch the exception that openssl_random_pseudo_byte() may emit.

<?php
    // PHP 7.4 way to check on random number generation
    try {
        $bytes = openssl_random_pseudo_bytes($i);
    } catch(\Exception $e) {
        die(Error while loading random number);
    }

    // Old way to check on random number generation
    $bytes = openssl_random_pseudo_bytes($i, $cstrong);
    if ($cstrong === false) {
        die(Error while loading random number);
    }
?>

See also openssl_random_pseudo_byte and PHP RFC: Improve `openssl_random_pseudo_bytes() <https://wiki.php.net/rfc/improve-openssl-random-pseudo-bytes>`_.

9.769.1. Suggestions

  • Skip the second argument, add a try/catch around the call to openssl_random_pseudo_bytes()
Short name Structures/OpensslRandomPseudoByteSecondArg
Rulesets CompatibilityPHP74
Severity Minor
Time To Fix Quick (30 mins)

9.770. parse_str() Warning

The parse_str() function parses a query string and assigns the resulting variables to the local scope. This may create a unexpected number of variables, and even overwrite the existing one.

<?php
  function foo( ) {
    global $a;

    echo $a;
  }

  parse_str('a=1'); // No second parameter
  foo( );
  // displays 1
?>

Always use an empty variable a second parameter to parse_str(), so as to collect the incoming values, and then, filter them in that array.

9.770.1. Suggestions

  • Use the second parameter when calling parse_url();
  • Change to PHP 8.0 version, which made the second argument compulsory
Short name Security/parseUrlWithoutParameters
Rulesets Security
Severity Major
Time To Fix Slow (1 hour)
ClearPHP know-your-variables

9.771. preg_match_all() Flag

preg_match_all() has an option to configure the structure of the results : it is either by capturing parenthesis (by default), or by result sets.

The second option is the most interesting when the following foreach() loop has to manipulate several captured strings at the same time. No need to use an index in the first array and use it in the other arrays.

<?php
$string = 'ababab';

// default behavior
preg_match_all('/(a)(b)/', $string, $r);
$found = '';
foreach($r[1] as $id => $s) {
    $found .= $s.$r[2][$id];
}

// better behavior
preg_match_all('/(a)(b)/', $string, $r, PREG_SET_ORDER);
$found = '';
foreach($r as $s) {
    $found .= $s[1].$s[2];
}

?>

The second syntax is easier to read and may be marginally faster to execute (preg_match_all() and foreach()).

9.771.1. Suggestions

  • Use flags to adapt the results of preg_match_all() to your code, not the contrary.
Short name Php/PregMatchAllFlag
Rulesets Suggestions
Severity Minor
Time To Fix Quick (30 mins)
Examples FuelCMS

9.772. preg_replace With Option e

preg_replace() supported the /e option until PHP 7.0. It allowed the use of eval()’ed expression as replacement. This has been dropped in PHP 7.0, for security reasons.

preg_replace() with /e option may be replaced with preg_replace_callback() and a closure, or preg_replace_callback_array() and an array of closures.

<?php

// preg_replace with /e
$string = 'abcde';

// PHP 5.6 and older usage of /e
$replaced = preg_replace('/c/e', 'strtoupper($0)', $string);

// PHP 7.0 and more recent
// With one replacement
$replaced = preg_replace_callback('/c/', function ($x) { return strtoupper($x[0]); }, $string);

// With several replacements, preventing multiple calls to preg_replace_callback
$replaced = preg_replace_callback_array(array('/c/' => function ($x) { return strtoupper($x[0]); },
                                              '/[a-b]/' => function ($x) { return strtolower($x[0]); }), $string);
?>

9.772.1. Suggestions

  • Replace call to preg_replace() and /e with preg_replace_callback() or preg_replace_callback_array()
Short name Structures/pregOptionE
Rulesets Analyze, CompatibilityPHP70, Security, CompatibilityPHP71, CompatibilityPHP72, CI-checks
Severity Major
Time To Fix Quick (30 mins)
Examples Edusoho

9.773. self, parent, static Outside Class

self, parent and static should be called inside a class or trait. PHP lint won’t report those situations.

self, parent and static may be used in a trait : their actual value will be only known at execution time, when the trait is used.

<?php
// In the examples, self, parent and static may be used interchangeably

// This raises a Fatal error
//Fatal error: Uncaught Error: Cannot access static:: when no class scope is active
new static();

// static calls
echo self::CONSTANTE;
echo self::$property;
echo self::method();

// as a type hint
function foo(static $x) {
    doSomething();
}

// as a instanceof
if ($x instanceof static) {
    doSomething();
}

?>

Such syntax problem is only revealed at execution time : PHP raises a Fatal error.

The origin of the problem is usually a method that was moved outside a class, at least temporarily.

See also Scope Resolution Operator (::).

Short name Classes/NoPSSOutsideClass
Rulesets Analyze, LintButWontExec
Severity Major
Time To Fix Slow (1 hour)

9.774. set_exception_handler() Warning

The set_exception_handler() callable function has to be adapted to PHP 7 : Exception is not the right typehint, it is now Throwable.

When in doubt about backward compatibility, just drop the typehint. Otherwise, use Throwable.

<?php

// PHP 5.6- typehint
class foo { function bar(\Exception $e) {} }

// PHP 7+ typehint
class foo { function bar(Throwable $e) {} }

// PHP 5 and PHP 7 compatible typehint (note : there is none)
class foo { function bar($e) {} }

set_exception_handler(foo);

?>
Short name Php/SetExceptionHandlerPHP7
Rulesets CompatibilityPHP70
Severity Major
Time To Fix Slow (1 hour)

9.775. strip_tags Skips Closed Tag

strip_tags() skips non-self closing tags. This means that tags such as <br /> will be ignored from the 2nd argument of the function.

<?php

$input = 'a<br />';

// Displays 'a' and clean the tag
echo strip_tags($input, '<br>');

// Displays 'a<br />' and skips the allowed tag
echo strip_tags($input, '<br/>');

?>

See also strip_tags.

9.775.1. Suggestions

  • Do not use self-closing tags in the 2nd parameter
Short name Structures/StripTagsSkipsClosedTag
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Quick (30 mins)

9.776. strpos() Too Much

strpos() covers the whole string before reporting 0. If the expected string is expected be at the beginning, or a fixed place, it is more stable to use substr() for comparison.

The longer the haystack (the searched string), the more efficient is that trick. The string has to be 10k or more to have impact, unless it is in a loop.

<?php

// This always reads the same amount of string
if (substr($html, 0, 6) === '<html>') {

}

// When searching for a single character, checking with a known position ($string[$position]) is even faster
if ($html[0] === '<') {

}

// With strpos(), the best way is to search for something that exist, and use absence as worst case scenario
if (strpos($html, '<html>') > 0) {

} else {
    //
}

// When the search fails, the whole string has been read
if (strpos($html, '<html>') === 0) {

}

?>

This applies to stripos() too.

9.776.1. Suggestions

  • Check for presence, and not for absence
  • use substr() and compare the extracted string
  • For single chars, try using the position in the string
Short name Performances/StrposTooMuch
Rulesets Analyze, CI-checks
Severity Minor
Time To Fix Instant (5 mins)
Examples WordPress

9.777. time() Vs strtotime()

time() is actually faster than strtotime() with ‘now’ key string.

<?php

// Faster version
$a = time();

// Slower version
$b = strtotime('now');

?>

This is a micro-optimisation. Relative gain is real, but small unless the function is used many times.

9.777.1. Suggestions

  • Replace strtotime() with time(). Do not change strtotime() with other value than ‘now’.
Short name Performances/timeVsstrtotime
Rulesets Performances
Severity Minor
Time To Fix Instant (5 mins)
Examples Woocommerce

9.778. var_dump()… Usage

var_dump(), print_r() or var_export() should not be left in any production code. They are debugging functions.

<?php

if ($error) {
    // Debugging usage of var_dump
    // And major security problem
    var_dump($query);

    // This is OK : the $query is logged, and not displayed
    $this->log(print_r($query, true));
}

?>

They may be tolerated during development time, but must be removed so as not to have any chance to be run in production.

9.778.1. Suggestions

  • Remove usage of var_dump(), print_r(), var_export() without 2nd argument, and other debug functions.
  • Push all logging to an external file, instead of the browser.
Short name Structures/VardumpUsage
Rulesets Analyze, Security, CI-checks
Severity Critical
Time To Fix Instant (5 mins)
ClearPHP no-debug-code
Examples Tine20, Piwigo