array_pop(): Unreachable statement - code above always terminates.

[mahagr]

Bug report (version 0.12.42)

If you have a queue with single item in it, phpstan seems to think that array_pop() returns null.

Code snippet that reproduces the problem

https://phpstan.org/r/57010e6f-71f7-4b56-9e14-e6b55b87cf47

function foo(): void
{
    $queue = ['asd'];
    $list = [];
    do {
        $current = array_pop($queue);
        if ($current === null) {
            break;
        }

        $list[] = $current;
    } while ($queue);
}

Output

Line 10: Unreachable statement - code above always terminates.

Expected output

No error

[mergeable]

This bug report is missing a link to reproduction on phpstan.org.
It will most likely be closed after manual review.

[jlherren]

phpstan/phpstan-src#333 should fix this. However PHPStan will still (correctly) report that the if-condition is always false. The do-while-loop will only ever execute once, thus the comparison will always be 'asd' === null.

[mahagr]

Yup, I just quickly stripped out some code to make a working example. Items were being pushed to the queue from within the loop.

[github-actions]

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