PHPStan incorrectly reports method.childReturnType error for generic template inheritance with $this types #13418

Bug report

PHPStan reports method.childReturnType errors when a child class overrides methods from a generic parent class that use $this in the return type annotation, even when the inheritance is
correctly defined.

Expected Behavior

The child class method return type should be considered compatible with the parent class method return type when:

• Child extends Parent with proper generic type specification
• Method signatures are identical
• Return types are logically compatible through inheritance

Actual Behavior

PHPStan reports:

Return type (HasOne<AgreementSignature, $this(Agreement)>) of method Agreement::signature()
should be compatible with return type (HasOne<AgreementSignature, $this(AbstractContract)>)
of method AbstractContract::signature()

/** @template TSignature of AbstractSignature */
abstract class AbstractContract extends Model
{
    /**
     * Eloquent relation to the contract's signature class to return latest Signatures.
     *
     * @return HasOne<TSignature, $this>
     */
    abstract public function signature(): HasOne;
}

/** @extends AbstractContract<AgreementSignature> */
final class Agreement extends AbstractContract
{
    #[Override]
    public function signature(): HasOne
    {
		return new HasOne(AgreementSignature::class, $this);
    }
}

Code snippet that reproduces the problem

https://phpstan.org/r/0ed44220-9626-459f-9eab-b6f37da57425

Expected output

I would expect there to be no errors

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