logicalOr.alwaysFalse

Code example

<?php declare(strict_types = 1);

function doFoo(int $x): void
{
	if ($x !== 0) {
		return;
	}

	// At this point $x is 0
	if (($x > 0) or ($x < 0)) { // ERROR: Result of or is always false.
		echo 'nonzero';
	}
}

Why is it reported?

PHPStan determined that the result of the or expression is always false. Both comparisons evaluate to false for the narrowed type of $x, making the entire expression always false. This usually indicates dead code, a logic error, or a condition that has already been checked earlier in the control flow.

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

How to fix it

Remove the redundant condition since the variable has already been narrowed:

 function doFoo(int $x): void
 {
 	if ($x !== 0) {
 		return;
 	}

-	if (($x > 0) or ($x < 0)) {
-		echo 'nonzero';
-	}
+	echo 'zero';
 }

Or fix the logic to test what was actually intended:

 function doFoo(int $x): void
 {
-	if ($x !== 0) {
+	if ($x > 10) {
 		return;
 	}

-	if (($x > 0) or ($x < 0)) {
+	if (($x > 5) or ($x < 0)) {
 		echo 'nonzero';
 	}
 }