Description:
------------
An overriding method in a subclass is technically still compatible if

* it gained a default value (or `= null` in case of class type hints), or
* a class type hint is changed into an ancestor class, or
* a type hint is removed.

These changes do not cause fatal errors in PHP 5.5, but do cause "Strict standards" warnings for the latter two. I believe this is incorrect: no warnings should be issued.

This was hinted at in a comment from 2012-02-11 on bug #46851.


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

class Fruit {}
class Banana extends Fruit {}
class Lemon extends Fruit {}

class Base
{
    public function methodOne(Banana $x) {}
    public function methodTwo(array $x) {}
}

class OverrideNullable extends Base
{
    public function methodOne(Banana $x = null) {}
    public function methodTwo(array $x = null) {}
}

class OverrideParent extends Base
{
    public function methodOne(Fruit $x) {}
}

class OverrideWildcard extends Base
{
    public function methodOne($x) {}
    public function methodTwo($x) {}
}

(new Base())->methodOne(new Banana());
(new Base())->methodTwo([]);

(new OverrideNullable())->methodOne();
(new OverrideNullable())->methodTwo();

(new OverrideParent())->methodOne(new Lemon());

(new OverrideWildcard())->methodOne('');
(new OverrideWildcard())->methodTwo('');

echo "Output intentionally left blank." , PHP_EOL;


Expected result:
----------------
Output intentionally left blank.


Actual result:
--------------
PHP Strict Standards:  Declaration of OverrideParent::methodOne() should be compatible with Base::methodOne(Banana $x) in /private/tmp/test.php on line 22

Strict Standards: Declaration of OverrideParent::methodOne() should be compatible with Base::methodOne(Banana $x) in /private/tmp/test.php on line 22
PHP Strict Standards:  Declaration of OverrideWildcard::methodOne() should be compatible with Base::methodOne(Banana $x) in /private/tmp/test.php on line 28

Strict Standards: Declaration of OverrideWildcard::methodOne() should be compatible with Base::methodOne(Banana $x) in /private/tmp/test.php on line 28
PHP Strict Standards:  Declaration of OverrideWildcard::methodTwo() should be compatible with Base::methodTwo(array $x) in /private/tmp/test.php on line 28

Strict Standards: Declaration of OverrideWildcard::methodTwo() should be compatible with Base::methodTwo(array $x) in /private/tmp/test.php on line 28
Output intentionally left blank.