Description:
------------
http://php.net/manual/en/language.oop5.interfaces.php#language.oop5.interfaces states in a note:

"The class implementing the interface must use the exact same method signatures as are defined in the interface. Not doing so will result in a fatal error."

Which doesn't seem to mention LS principle in any way. For more information, check https://bugs.php.net/bug.php?id=73220.

Test script:
---------------
interface A
{
    public function test($one = null);
}

class B implements A
{
    public function test($one = null, $two = null)
    {
        var_dump($one, $two);
    }
}


Expected result:
----------------
Fatal error: Declaration of B::test($one, $two) must be compatible with A::test($one = NULL)


Actual result:
--------------
No error.