Error Identifier: notEqual.notAllowed

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);

$result = 123 != 456; // error: Loose comparison via "!=" is not allowed.

Why is it reported? #

Loose comparison (!=) uses PHP’s type juggling rules to compare values, which can produce surprising and hard-to-predict results. For example, "0" != "" evaluates to true, but 0 != "" evaluates to false. These implicit type conversions are a common source of bugs.

This error is reported by phpstan-strict-rules.

How to fix it #

Use strict comparison (!==) instead, which compares both the value and the type without implicit conversion.

-$result = 123 != 456;
+$result = 123 !== 456;

If the values have different types and a comparison is still needed, cast one operand explicitly to make the intent clear.

-if ($userInput != 0) {
+if ((int) $userInput !== 0) {
 	// ...
 }

How to ignore this error #

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

// @phpstan-ignore notEqual.notAllowed
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.notAllowed

Rules that report this error #

PHPStan\Rules\DisallowedConstructs\DisallowedLooseComparisonRule [1] phpstan/phpstan-strict-rules

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