Description:
------------
Good evening. I think the following code should be allowed.

Test script:
---------------
<?php

class ParentClass
{
    
}

class ChildClass extends ParentClass
{
    
}

class A
{
    public function test() : ParentClass{}    
}

class B extends A
{
    public function test() : ChildClass{}    
}

Expected result:
----------------
No error.

Actual result:
--------------
Fatal error: Declaration of B::test(): ChildClass must be compatible with A::test(): ParentClass