array_pop output should not be null given a full array

[muglug]

Found this while deciding whether to add similar functionality in another package.

/**
 * @param array<int, int> $arr
 */
function foo(array $arr) : int {
    $a = array_pop($arr);
	
    if ($arr) {
        return $a;
    }
	
    return 0;
}

Expected: no issue
Actual: Function foo() should return int but returns int|null
https://phpstan.org/r/693d212d-fec7-45fd-bce5-7bcf7c01afff

[ondrejmirtes]

This falls under dependent types, here are other examples: https://github.com/phpstan/phpstan/milestone/12

I'm not sure if it's worth tackling since the code is really analyser-unfriendly. I have no idea right now how I would model it and approach this problem.

[muglug]

I have no idea right now how I would model it and approach this problem.

I don't either.

Here's where I use this pattern.

Easy obvious workaround is to assert if ($a && $arr), but that doesn't feel great.

[hrach]

I don't see any reason to support this. Statically & strictly typed language don't to this either.
https://pl.kotl.in/B1BOqoIeV

[muglug]

@hrach

Statically & strictly typed language don't to this either.

That in itself shouldn't be an argument, I don't think. For example, those tools generally do not allow this code:

function takesObject(object $_o): void {}
function foo(?object $a, ?object $b): void {
  if ($a || $b) {
    if ($a) {
      $c = $a;
    } else {
      $c = $b;
    }

    takesObject($c);
  }
}

But with the right analysis a tool can understand what's happening: https://getpsalm.org/r/680d27b861

[ondrejmirtes]

Fixed the issue in the OP: https://phpstan.org/r/14f773c7-b8fd-4666-b0d2-5f6ba10037cf

I'll keep track of #1722 (comment) to do it later :)

Fixed by: phpstan/phpstan-src@a9d5c8b

[github-actions]

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