get_class does not return false

[kamil-tekiela]

Technically all functions could return false or null when a wrong parameter is provided, but that was undefined behavour in PHP <8 and should not be relied upon.

[kamil-tekiela]

Ok, it did return false prior to PHP 8. I will change the PR to account for this tomorrow.

[weirdan]

Did it ever return false without also producing a warning?

[kamil-tekiela]

Did it ever return false without also producing a warning?

Not to my knowledge. See https://heap.space/xref/PHP-7.4/Zend/zend_builtin_functions.c?r=1e0bc6e3#955

[orklah]

not since PHP 5.3:
https://3v4l.org/XBMmE
https://3v4l.org/clSSM
https://3v4l.org/n7SgA

Psalm is already emitting an error in all those cases. The only case where Psalm does not emit error is: https://psalm.dev/r/781da1e35e but it gives a warning even in PHP 5.2. I say we can get rid of the false return as we already did on such cases for other functions

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/781da1e35e

<?php
var_dump(get_class());

Psalm output (using commit bc11b10):

ERROR: ForbiddenCode - 2:1 - Unsafe var_dump

[weirdan]

If we can reliably flag cases where it would return false then we don't need |false in the signature.

There's one I can think of: calling get_class() without arguments in a non-class context: https://psalm.dev/r/58287e0c4e. I think it could be handled similarly to __CLASS__ reference in a non-class context: https://psalm.dev/r/dd677898db

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/58287e0c4e

<?php

echo get_class();

Psalm output (using commit bc11b10):

No issues!

https://psalm.dev/r/dd677898db

<?php
echo __CLASS__;

Psalm output (using commit bc11b10):

ERROR: UndefinedConstant - 2:6 - Cannot get __class__ outside a class

[orklah]

It's not flagged by Psalm but it never worked AND always emitted a warning or worse: https://3v4l.org/TkeS5 (weirdly, it started as a warning, then was an error, again a warning and it's now an error!)

[weirdan]

but it never worked AND always emitted a warning

It's a good indication that we need to flag it.

[orklah]

That should do it: #7043

[kamil-tekiela]

What about this PR? Is it ok to just remove |false from all versions or should I add delta?

[weirdan]

Just dropping |false would be perfect.

[orklah]

Thanks!