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Error Identifier: logicalOr.leftAlwaysFalse

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 doFoo(int $x): void
{
	if ($x > 10) {
		return;
	}

	// At this point $x is <= 10
	$result = ($x > 10) or ($x === 5); // ERROR: Left side of or is always false.
}

Why is it reported? #

PHPStan determined that the left side of the or expression is always false. This means the left operand does not contribute to the result – the entire expression depends solely on the right side. This usually indicates a logic error, a redundant check, or a condition that has already been narrowed by earlier control flow.

The or keyword is the low-precedence version of ||. This identifier specifically covers the or keyword; for ||, see booleanOr.leftAlwaysFalse.

How to fix it #

Remove the redundant left side or fix the condition to test what was actually intended:

 <?php declare(strict_types = 1);
 
 function doFoo(int $x): void
 {
 	if ($x > 10) {
 		return;
 	}

-	$result = ($x > 10) or ($x === 5);
+	$result = ($x === 5);
 }

Or fix the condition if the logic is wrong:

 <?php declare(strict_types = 1);
 
 function doFoo(int $x): void
 {
 	if ($x > 10) {
 		return;
 	}

-	$result = ($x > 10) or ($x === 5);
+	$result = ($x >= 8) or ($x === 5);
 }

How to ignore this error #

You can use the identifier logicalOr.leftAlwaysFalse to ignore this error using a comment:

// @phpstan-ignore logicalOr.leftAlwaysFalse
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: logicalOr.leftAlwaysFalse

Rules that report this error #

• PHPStan\Rules\Comparison\BooleanOrConstantConditionRule [1]

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