Error Identifier: logicalXor.rightAlwaysFalse

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 test(bool $a): bool
{
	return $a xor ($a && !$a);
}

Why is it reported? #

The right side of the xor operator always evaluates to false. This makes the xor expression equivalent to just the left side, because $left xor false always equals $left. The right operand is redundant and likely indicates a logic error.

How to fix it #

Review the logic and either remove the xor expression entirely if the right side is not needed, or correct the right-side condition so that it can actually evaluate to true.

 <?php declare(strict_types = 1);
 
 function test(bool $a): bool
 {
-	return $a xor ($a && !$a);
+	return $a xor someOtherCondition();
 }

How to ignore this error #

You can use the identifier logicalXor.rightAlwaysFalse to ignore this error using a comment:

// @phpstan-ignore logicalXor.rightAlwaysFalse
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: logicalXor.rightAlwaysFalse

Rules that report this error #

PHPStan\Rules\Comparison\LogicalXorConstantConditionRule [1]

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