Bug #72119 [Nab]: Interface declaration compatibility regression with default values

Edit report at https://bugs.php.net/bug.php?id=72119&edit=1

 ID:                 72119
 Updated by:         [email protected]
 Reported by:        ben dot davies at gmail dot com
 Summary:            Interface declaration compatibility regression with
                     default values
 Status:             Not a bug
 Type:               Bug
 Package:            PHP Language Specification
 PHP Version:        7.0.6
 Assigned To:        levim
 Block user comment: N
 Private report:     N

 New Comment:

The original problem was introduced by attempt to fix #71428 (that expects exactly the opposite behavior) in commit ee9a78a033696ff9546fb1dbfecd28f20477b511


Previous Comments:
------------------------------------------------------------------------
[2016-04-28 15:26:30] ben dot davies at gmail dot com

Hi both,

No doubt you are both correct, but this appears to be a BC break.
This works in every version of php up to 7.0.6.

https://3v4l.org/VhEtd

Thanks

------------------------------------------------------------------------
[2016-04-28 15:23:48] [email protected]

I have confirmed that this is not a bug. The reason is that in the interface you are permitted to pass null:

<?php
$Foo->bar(null);
?>

However, in the implementing class Hello it would not be permitted. Everything permitted in the parent must also be permitted in the child, thus it is not a bug.

------------------------------------------------------------------------
[2016-04-28 15:22:29] [email protected]

This is not a bug; your code is a LSP violation which had been fixed in bug #71428.

In the concrete example, the Foo::bar() function can be passed null, but Hello::bar() cannot.

[This is something we try to fix with nullable parameters/null unions in 7.1.]

------------------------------------------------------------------------
[2016-04-28 15:18:48] [email protected]

This was changed in commit e9d65160 by Dmitry. It appears to be a fix for a different bug (71978).

------------------------------------------------------------------------
[2016-04-28 11:33:37] ben dot davies at gmail dot com

Description:
------------
I wanted to raise this against 7.0.6, but it was not available in the list above, despite being released?

There seems to be a regression in interface method declaration compatibility checking.
The below test script only fails on 7.0.6.

It also only fails if the $baz is type hinted as array.

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

interface Foo {
    public function bar(array $baz = null);
}

class Hello implements Foo {
    public function bar(array $baz = [])
    {

    }
}

Expected result:
----------------
N/A

Actual result:
--------------
Fatal error: Declaration of Hello::bar(array $baz = Array) must be compatible with Foo::bar(array $baz = NULL) in /in/VhEtd on line 7

Process exited with code 255.


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



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Edit this bug report at https://bugs.php.net/bug.php?id=72119&edit=1