Error Identifier: notEqual.alwaysTrue

Every error reported by PHPStan has an error identifier. Here’s a list of all error identifiers. In PHPStan Pro you can see the error identifier next to each error and filter errors by their identifiers.

Code example #

<?php declare(strict_types = 1);

function check(int $a, string $b): void
{
	if ($a != $b) { // ERROR: Loose comparison using != between int and string will always evaluate to true.
		// always reached
	}
}

Why is it reported? #

The loose comparison using != between two expressions will always evaluate to true based on the types PHPStan has inferred. This means the condition is always satisfied, making it redundant, and any else branch would be dead code.

The != operator performs a loose (type-juggling) comparison. PHPStan reports this when it can determine from the types that the two values can never be loosely equal, regardless of the actual runtime values.

How to fix it #

Review the logic of the comparison. The condition is always true and the else branch (if any) is unreachable.

If the comparison is intentional but the types are wrong, fix the types so the comparison becomes meaningful:

 <?php declare(strict_types = 1);
 
-function check(int $a, string $b): void
+function check(int $a, int $b): void
 {
 	if ($a != $b) {
 		// ...
 	}
 }

Consider using strict comparison (!==) instead of loose comparison, which avoids type-juggling surprises:

 <?php declare(strict_types = 1);
 
 function check(int $a, string $b): void
 {
-	if ($a != $b) {
+	if ($a !== (int) $b) {
 		// ...
 	}
 }

If the branch is always taken and the condition is unnecessary, simplify the code by removing the condition:

 <?php declare(strict_types = 1);
 
 function check(int $a, string $b): void
 {
-	if ($a != $b) {
-		doSomething();
-	}
+	doSomething();
 }

How to ignore this error #

You can use the identifier notEqual.alwaysTrue to ignore this error using a comment:

// @phpstan-ignore notEqual.alwaysTrue
codeThatProducesTheError();

You can also use only the identifier key to ignore all errors of the same type in your configuration file in the ignoreErrors parameter:

parameters:
	ignoreErrors:
		-
			identifier: notEqual.alwaysTrue

Rules that report this error #

PHPStan\Rules\Comparison\ConstantLooseComparisonRule [1]

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