Description:
------------
Having script like that

<?php
class ModelBase {}

class ModelChild extends ModelBase {}

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

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

ordinary

php file.php

throws

PHP Fatal error:  Declaration of B::test(): ModelChild must be compatible with A::test(): ModelBase in file.php on line 13

PHP 7.2.0RC3 (cli) (built: Sep 28 2017 16:28:37) ( NTS )
Copyright (c) 1997-2017 The PHP Group


Test script:
---------------
<?php
class ModelBase {}

class ModelChild extends ModelBase {}

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

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

Expected result:
----------------
As ModelChild extends ModelBase, methods expected to return ModelBase should be allowed to be overriden and return its subclass (ModelChild) as it is allowed in any other language that follows OOP principles.

Actual result:
--------------
PHP Fatal error:  Declaration of B::test(): ModelChild must be compatible with A::test(): ModelBase in file.php on line 13