Exception catch scope infers incorrect types

[cs278]

Summary of a problem or a feature request

Exception catch scope infers incorrect types. Apologies this isn't easy to describe and I didn't have any luck finding a similar issue. The code below is a minimum reproducer of the problem.

Code snippet that reproduces the problem

<?php declare(strict_types = 1);

/** @var \stdClass|null */
$object = null;

try {
    if ($object === null) {
        throw new \InvalidArgumentException();
    }

    throw new \RuntimeException(); // If you remove this the same error is present as well, which makes even less sense to me
} catch (\Throwable $e) {
    if ($object === null) { // Strict comparison using === between stdClass and null will always evaluate to false.
    }
}

https://phpstan.org/r/c56d3540-d5fa-4366-8ca8-fb6bb63d2484

Expected output

No error

[cs278]

@ondrejmirtes this seems to have been fixed with: 00c781c

[ondrejmirtes]

Hi, that's weird. This area definitely hasn't been implemented yet. PHPStan does not understand when are exceptions in try try block and what are the resulting types in respective catch blocks.

[phpstan-bot]

@cs278 PHPStan now reports different result with your code snippet:

@@ @@
-13: Strict comparison using === between stdClass and null will always evaluate to false.
+No errors

[ondrejmirtes]

I have no idea why this isn't reported by the playground, but locally it's still just stdClass, not stdClass|null.

[ondrejmirtes]

Fixed by: phpstan/phpstan-src#481

[github-actions]

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