Bug #75385 [Com]: Fatal error after overriding method and returning subclass of what parent do

Edit report at https://bugs.php.net/bug.php?id=75385&edit=1

 ID:                 75385
 Comment by:         Wes dot example at example dot org
 Reported by:        carlos at wfmh dot org dot pl
 Summary:            Fatal error after overriding method and returning
                     subclass of what parent do
 Status:             Open
 Type:               Bug
 Package:            PHP Language Specification
 Operating System:   Ubuntu
 PHP Version:        7.2.0RC4
 Block user comment: N
 Private report:     N

 New Comment:

Sadly php doesn't support return type covariance yet.

For now you can doc-comment /** @return ModelChild */ in class B.


Previous Comments:
------------------------------------------------------------------------
[2017-10-15 21:41:24] carlos at wfmh dot org dot pl

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



------------------------------------------------------------------------



--
Edit this bug report at https://bugs.php.net/bug.php?id=75385&edit=1