Bug #80126 [Com]: Covariant return types failing compilation
| From: | danack@php.net | Date: | Mon, 21 Sep 2020 12:32:03 +0000 |
| Subject: | Bug #80126 [Com]: Covariant return types failing compilation | ||
| References: | 1 | Groups: | php.bugs |
| Request: | Send a blank email to php-bugs+get-229112@lists.php.net to get a copy of this message | ||
Edit report at https://bugs.php.net/bug.php?id=80126&edit=1
ID: 80126
Comment by: danack@php.net
Reported by: terence-marks at zencontrol dot com
Summary: Covariant return types failing compilation
Status: Open
Type: Bug
Package: Compile Failure
Operating System: Debian Buster
PHP Version: 7.4.10
Block user comment: N
Private report: N
New Comment:
I don't think the extra interface is necessary to show the bug. This seems to fail also..
interface inty {
public function intmethod(): inty;
}
abstract class AbstractClass implements inty {
public function intmethod(): inty
{
return new static();
}
}
class Concrete extends AbstractClass { }
class ExtendedConcrete extends Concrete {
// fails
public function intmethod(): ExtendedConcrete {
return new static();
}
// Works
// public function intmethod(): Concrete {
// return new static();
// }
}
Previous Comments:
------------------------------------------------------------------------
[2020-09-21 01:42:27] terence-marks at zencontrol dot com
Description:
------------
Discovered an issue with narrowing return type using covariance.
I have a chain of inheritance (...ignore implementation details) from which at the lowest level I
attempt to narrow the return type for an inherited method. When running the code PHP fails at
compilation stating the method is not compatible.
Now the weird part is it seems the covariance check passes if I remove all interfaces from the
lowest level (see example).
The attached test script should point you guys in the right direction.
Cheers,
Terence
Test script:
---------------
<?php
interface Poo
{
public function poo(): Poo;
}
abstract class AbstractPoo implements Poo
{
public function poo(): Poo
{
return new static();
}
}
class ConcretePoo extends AbstractPoo
{
}
interface B
{
}
// Fails if interface is present
class ExtendedConcretePoo extends ConcretePoo implements B
{
public function poo(): ExtendedConcretePoo
{
return new static();
}
}
// Does not fail if no interfaces present
//class ExtendedConcretePoo extends ConcretePoo
//{
// public function poo(): ExtendedConcretePoo
// {
// return new static();
// }
//}
$e = new ExtendedConcretePoo();
$r = $e->poo();
Expected result:
----------------
No compilation errors.
Actual result:
--------------
Declaration of ExtendedConcretePoo::poo(): ExtendedConcretePoo must be compatible with
AbstractPoo::poo()
------------------------------------------------------------------------
--
Edit this bug report at https://bugs.php.net/bug.php?id=80126&edit=1