#8575 More strict signature for implode function

[SLaVeZ]

Fix for issue #8575

[orklah]

Thanks for trying to fix the issue :) Unfortunately, this is not correct.

Stringable is a symbol that was added on PHP 8. I'm not exactly sure how Psalm would react exactly on lower versions (most probably allow a Stringable class that would exist in user code or possibly crash outright) but it can't be good.

There is a stringable-object pseudo-type that is translated into an object that happens to have a __toString method in Psalm. It would be more correct in this situation but Psalm doesn't seem to enforce it: https://psalm.dev/r/8233ca5c0a

This is a bug that should be fixed first.

Also, the actual fix should be located in

psalm/stubs/CoreGenericFunctions.phpstub

Line 607 in 285740a

function implode($separator, array $array = []) : string {}

instead of callmaps. When a stub is present, it overrides the callmap

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/8233ca5c0a

<?php

 implode2([new stdClass]);

/**
 * @param array<stringable-object> $separator
 */
function implode2($separator) : void {}

Psalm output (using commit 212281d):

INFO: UnusedParam - 8:19 - Param $separator is never referenced in this method

[weirdan]

This is fixed in #8688