test: add failing test case for bug #11857

[calebdw]

Adds a failing test for phpstan/phpstan#11857

[ondrejmirtes]

Please see my commits. Can you grab the PHAR from https://github.com/phpstan/phpstan-src/actions/runs/11701663721, copy it into your vendor/phpstan/phpstan/ and test it thoroughly on Larastan and real-world projects to see if it fixes the issue? Thanks.

[ondrejmirtes]

Also I modified the test expectation and added one ignore, please tell me if it's still okay.

[calebdw]

@ondrejmirtes,

This fixed the relation errors, but it caused errors when using a trait with methods that return $this in a final class. I added another test file to demonstrate this failure

[phpstan-bot]

This pull request has been marked as ready for review.

[ondrejmirtes]

I'm pretty confident with the changes now.

[ondrejmirtes]

Thank you.

[calebdw]

Thank you!!

[kayw-geek]

Hi @calebdw, Thank improve the generic relation to Relations! While enhancing generic relations for Relations, I encountered an issue: when a final parent class overrides method uses a PHPDoc return type with $this in a generic parameter, PHPStan a return type incompatibility.

Reproduction Code:

<?php

namespace Bug11857;

use function PHPStan\Testing\assertType;

abstract class Model {
    /** @return BelongsTo<*, *> */
    public function belongsTo(string $related): BelongsTo {
        return new BelongsTo();
    }
}

/**
 * @template TRelatedModel of Model
 * @template TDeclaringModel of Model
 */
class BelongsTo {}

class Post extends Model {
    /** @return BelongsTo<User, $this> */
    public function user(): BelongsTo {
        return $this->belongsTo(User::class);
    }
}

final class ChildPost extends Post {
    public function user(): BelongsTo {
        return $this->belongsTo(User::class);
    }
}

function test(ChildPost $child): void {
    assertType('Bug11857\BelongsTo<Bug11857\User, Bug11857\ChildPost>', $child->user());
}

Error Output:

------ ---------------------------------------------------------------
Line   test.php                                                       
------ ---------------------------------------------------------------
42     Return type (Bug11857\BelongsTo<Bug11857\User, $this(Bug11857\ChildPost)>) 
       of method Bug11857\ChildPost::user() should be compatible with 
       return type (Bug11857\BelongsTo<Bug11857\User, $this(Bug11857\Post)>) 
       of method Bug11857\Post::user()      
       🪪 method.childReturnType                                      
------ ---------------------------------------------------------------

PHPStan version is 2.1.6

[calebdw]

@kayw-geek,

There's no reason for the child to override the parent user method:

class Post extends Model {
    /** @return BelongsTo<User, $this> */
    public function user(): BelongsTo {
        return $this->belongsTo(User::class);
    }
}
final class ChildPost extends Post {
}

However, please open new bug reports so we can better track them