(Throwable~PDOException)::getCode() should be an int

[VincentLanglet]

Follow up of
#7390
#7525
#7673
@orklah

There is an error in psalm with
https://psalm.dev/r/23800504eb
but it works fine for phpstan
https://phpstan.org/r/014a6319-6af4-4fac-971d-4f4dbb76f57d

Is possible to say to psalm that (Throwable~ PDOException)::getCode() always return an int ?

Current PHPStan implementation: https://github.com/phpstan/phpstan-src/blob/1.9.x/src/Type/Php/ThrowableReturnTypeExtension.php
Current Psalm implementation:

psalm/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallReturnTypeFetcher.php

Line 102 in 65c31ce

if ($premixin_method_id->method_name === 'getcode'

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/23800504eb

<?php

function test(Throwable $e): int {
    if (!$e instanceof Exception) {
        return $e->getCode();
    }
    
    return 0;
}

Psalm output (using commit c3cc906):

ERROR: InvalidReturnStatement - 5:16 - The inferred type 'int|string' does not match the declared return type 'int' for test

ERROR: InvalidReturnType - 3:30 - The declared return type 'int' for test is incorrect, got 'int|string'

[orklah]

Psalm can't handle Throwable~PDOException as a type in itself.

This means this can't be handled in Psalm with the current type system: https://phpstan.org/r/0112ebba-a9c6-454d-9182-a0e78fa7d014

However, there is a small trick that we can use for your specific example of Throwable~Exception because it can be transformed into Error and Error::getCode is indeed an int

If you're interested, this could be handled the same way as DateTime/DateTimeImmutable:

psalm/src/Psalm/Internal/Type/NegatedAssertionReconciler.php

Line 151 in d0be59e

&& $assertion_type instanceof TNamedObject

[weirdan]

Can't we access (and evaluate) assertions in MethodCallReturnTypeFetcher?