fix (DateTime|DateTimeImmutable)::modify() return types

[DaDeather]

#9042 caused issues to any called method on an instance of DateTime|DateTimeImmutable after calling the modify method.

This fixes #9171

[pilif]

This will cause #9042 to be re-opened though. ˋmodify()ˋ returns something of the same type that it was called on which is consistent to the ˋstaticˋ return type

[DaDeather]

Do you got any better idea how to solve this correctly? TBH i'm not really into the codebase of psalm yet. Which is why this is the only thing I came up with up till now 🤷.

[DaDeather]

FYI: another approach I found would be to set:
$event->getContext()->self = $event->getCalledFqClasslikeName() ?? $event->getFqClasslikeName();
right before the return.

This would also fix this issue. But as I said before I'm not well into the ecosystem of psalm 🤷.

[DaDeather]

Is there anything I can do to make this one happen soon?

[weirdan]

I see where the confusion is. Signature return types and return value types, while being related concepts, are not the same thing. static is a relative type which is only valid in the context of the original class. When it's leaked outside, it may make Psalm assume funny things happen, like this: https://psalm.dev/r/c23709c02e

In the snippet above, Psalm assumes you're trying to call Unrelated::format() because static is interpreted in the context of class Unrelated.

@pilif with this PR, your snippet reports $foo2 from #9042 to be Subclass, as it should. In fact, it's included in a test.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/c23709c02e

<?php

class Subclass extends DateTimeImmutable
{
}

class Unrelated {
    public function doThings(): void {

        $foo = new Subclass('2023-01-01 12:12:13');
        $foo2 = $foo->modify('+7 days');
        /** @psalm-trace $foo2 */;
        echo $foo2->format('Y-m-d');
    }
    public function format(int $_p): never { exit; }
}

Psalm output (using commit 8e0fd88):

INFO: Trace - 12:34 - $foo2: Subclass&static

ERROR: InvalidScalarArgument - 13:28 - Argument 1 of Unrelated::format expects int, but 'Y-m-d' provided

ERROR: NoValue - 13:14 - All possible types for this argument were invalidated - This may be dead code

[weirdan]

@DaDeather would you mind rebasing this on top of master? I think it should clear up BCC failures.

[weirdan]

Thanks!