Incomplete return type for mb_split() function

[ryanhobrock]

Function mb_split() should have a return type of array|false per the PHP documentation. The Psalm call maps only have array leading to a TypeDoesNotContainType "list<string> does not contain false" error when type checking. See https://psalm.dev/r/0b69779c9f to reproduce the issue.

Changing the call maps from:

'mb_split' => ['list<string>', 'pattern'=>'string', 'string'=>'string', 'limit='=>'int'],

to:

'mb_split' => ['list<string>|false', 'pattern'=>'string', 'string'=>'string', 'limit='=>'int'],

should resolve it.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/0b69779c9f

<?php

$text = 'Hello world!';

$split = mb_split(' ', $text);

if ($split === false) {
    // Do something
}

Psalm output (using commit 477c011):

ERROR: TypeDoesNotContainType - 7:5 - list<string> does not contain false

[orklah]

Do you have a code that would actually make mb_split returns false?

Sometimes, when we're sure Psalm will catch every case that would make a function errors, we allow ourselves to not include the error return for better inference, but I'm not sure this is the case here...

[AndrolGenhald]

@orklah I spent a minute looking at that a couple hours ago because I had the same thought, there's one case that probably shouldn't happen, but there are also 2 valid cases: https://3v4l.org/dN6pD https://psalm.dev/r/57fd317561

[orklah]

Cool, thanks for confirmation. @ryanhobrock you correctly identified what needed to change. Small caveat, you need to change this in CallMap and CallMap_historical.

Can you push a PR?

[RishiKumarRay]

@orklah I would to raise PR for these changes, can you please assign me

[orklah]

With pleasure :)

[RishiKumarRay]

Hey @orklah in which directory can i Find the files CallMap and CallMap_historical as you said the changes are to be made in this 2 files?

[orklah]

Just right here: https://github.com/vimeo/psalm/tree/4.x/dictionaries

[RishiKumarRay]

@orklah cool ! I found it , Thanks a lot , will be generating a PR soon

[RishiKumarRay]

@orklah please do the review the PR #7432 , Thank you

[ryanhobrock]

Thank you @orklah, @AndrolGenhald, and @RishiKumarRay for the quick work on this!