.. _php-concatandaddition:

.. _concat-and-addition:

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.``
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.

.. code-block:: php
   
   <?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);
   
   ?>

See also `Change the precedence of the concatenation operator <https://wiki.php.net/rfc/concatenation_precedence>`_.

Related PHP errors 
-------------------

  + `0 <https://php-errors.readthedocs.io/en/latest/messages/The+behavior+of+unparenthesized+expressions+containing+both+%27.%27+and+%27%2B%27%2F%27-%27+will+change+in+PHP+8%3A+%27%2B%27%2F%27-%27+will+take+a+higher+precedence.html>`_
  + `1 <https://php-errors.readthedocs.io/en/latest/messages/The+behavior+of+unparenthesized+expressions+containing+both+%27.%27+and+%27%3E%3E%27%2F%27%3C%3C%27+will+change+in+PHP+8%3A+%27%3C%3C%27%2F%27%3E%3E%27+will+take+a+higher+precedence.html>`_



Connex PHP features
-------------------

  + `addition <https://php-dictionary.readthedocs.io/en/latest/dictionary/addition.ini.html>`_
  + `concatenation <https://php-dictionary.readthedocs.io/en/latest/dictionary/concatenation.ini.html>`_


Suggestions
___________

* Add parenthesis around the addition to ensure its expected priority
* Move the addition outside the concatenation




Specs
_____

+------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Short name       | Php/ConcatAndAddition                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
+------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Rulesets         | :ref:`All <ruleset-All>`, :ref:`Analyze <ruleset-Analyze>`, :ref:`CE <ruleset-CE>`, :ref:`CI-checks <ruleset-CI-checks>`, :ref:`Changed Behavior <ruleset-Changed-Behavior>`, :ref:`CompatibilityPHP53 <ruleset-CompatibilityPHP53>`, :ref:`CompatibilityPHP54 <ruleset-CompatibilityPHP54>`, :ref:`CompatibilityPHP55 <ruleset-CompatibilityPHP55>`, :ref:`CompatibilityPHP56 <ruleset-CompatibilityPHP56>`, :ref:`CompatibilityPHP70 <ruleset-CompatibilityPHP70>`, :ref:`CompatibilityPHP71 <ruleset-CompatibilityPHP71>`, :ref:`CompatibilityPHP72 <ruleset-CompatibilityPHP72>`, :ref:`CompatibilityPHP73 <ruleset-CompatibilityPHP73>`, :ref:`CompatibilityPHP74 <ruleset-CompatibilityPHP74>`, :ref:`CompatibilityPHP80 <ruleset-CompatibilityPHP80>`, :ref:`Top10 <ruleset-Top10>` |
+------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Exakat since     | 1.8.0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
+------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| PHP Version      | All                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
+------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Severity         | Minor                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
+------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Time To Fix      | Quick (30 mins)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
+------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Changed Behavior | PHP 8.0 - `More <https://php-changed-behaviors.readthedocs.io/en/latest/behavior/.html>`__                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
+------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Precision        | Very high                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
+------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Available in     | `Entreprise Edition <https://www.exakat.io/entreprise-edition>`_, `Community Edition <https://www.exakat.io/community-edition>`_, `Exakat Cloud <https://www.exakat.io/exakat-cloud/>`_                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+