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Error Identifier: booleanOr.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 $i): void
{
	$zero = 0;
	if ($zero || $i > 0) {
		// ...
	}
}

Why is it reported? #

The left side of the || (boolean OR) expression always evaluates to false. While the overall expression might still be true depending on the right side, having a left operand that is always falsy indicates dead code or a logic error. The left operand serves no purpose because the result of the || expression is entirely determined by the right side.

In the example above, $zero is always 0, which is falsy in PHP, so the left side of || is always false.

How to fix it #

Remove the redundant left operand:

 <?php declare(strict_types = 1);
 
 function doFoo(int $i): void
 {
-	$zero = 0;
-	if ($zero || $i > 0) {
+	if ($i > 0) {
 		// ...
 	}
 }

Or fix the logic to use the correct variable:

 <?php declare(strict_types = 1);
 
-function doFoo(int $i): void
+function doFoo(int $i, bool $flag): void
 {
-	$zero = 0;
-	if ($zero || $i > 0) {
+	if ($flag || $i > 0) {
 		// ...
 	}
 }

How to ignore this error #

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

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

Rules that report this error #

• PHPStan\Rules\Comparison\BooleanOrConstantConditionRule [1]

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