1.2.819. No Null With Null Safe Operator

When building an expression with a null-safe operator, it may fail and produce a NULL as a result. When the last method of the expression also returns null (or void, which is transformed in null), then it is not possible to differentiate between a failure and a valid execution of the method.

As such, it is recommended to avoid finishing with a method that returns null, in an expression that uses a null-safe operator.

<?php

class x {
     function foo($a) : ?int {
             if ($a % 2) {
                     return $a;
             } else {
                     return null;
             }
     }
}

$x = x::getInstance(x::class);
$result = $x?->foo($a);

// Is that an error or a valid result ?
if ($result === null) { }

?>

1.2.819.1. Suggestions

• Avoid using the null-safe operator in that expression

• Make the last property / method in the expression not return null

1.2.819.2. Specs

Short name	Classes/NoNullWithNullSafeOperator
Rulesets	All, Analyze, Changed Behavior, Class Review
Exakat since	2.6.4
PHP Version	8.1
Severity	Minor
Time To Fix	Slow (1 hour)
Precision	High
Features	nullsafe-object-operator
Available in	Entreprise Edition, Exakat Cloud