False positive when comparing ReflectionNamedType::getName() with 'static'

[BenMorel]

When ReflectionNamedType::isBuiltin() returns false, Psalm assumes that getName() returns a class-string:

if ($returnType instanceof \ReflectionNamedType) {
    if (! $returnType->isBuiltin() && $returnType->getName() !== 'static') {
        
    }
}

Psalm output (using commit 8b7bc07):

ERROR: RedundantCondition - 16:39 - 'static' can never contain class-string

Demo: https://psalm.dev/r/2c06d6b1d3

Even though 'static' is also a valid return type since PHP 8.0: https://3v4l.org/ZAqYK

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/2c06d6b1d3

<?php

namespace Test;

class Foo {
    public function bar(): static {
    	return $this;
    }
}

$class = new \ReflectionClass(Foo::class);
$method = $class->getMethod('bar');

$returnType = $method->getReturnType();
if ($returnType instanceof \ReflectionNamedType) {
    if (! $returnType->isBuiltin() && $returnType->getName() !== 'static') {
        
    }
}

Psalm output (using commit 8b7bc07):

ERROR: RedundantCondition - 16:39 - 'static' can never contain class-string

[AndrolGenhald]

Looks to me like the assertion in the stub needs changed from class-string to class-string|'static'|'self'. Are there any other possible return values we're missing?

[BenMorel]

@AndrolGenhald Good point about self, I thought this would be replaced with the FQCN by reflection or even at compilation time, but it looks like it's not, it's actually returning 'self': https://3v4l.org/U3JtZ

I don't see any other possible return value, so class-string|'static'|'self' should be alright.

I couldn't find where the return type is documented, it's not in the CallMap at least. Because the result is dependent on whether isBuiltin() has been called first, I guess there's some custom logic around this class.

[AndrolGenhald]

It's in stubs/Reflection.phpstub, it just uses @psalm-assert-if-false to assert the type of $this->getName().

[BenMorel]

@AndrolGenhald TIL, thanks! Fixed in #8201.