sample.php

<?php
function f($p0, DateInterval $p1 = null) {}
function g(DateInterval $p0 = null, $p1) {}
function j(DateInterval $p0 = null, $p1 = null) {}
function k($p0 = null, DateInterval $p1 = null) {}
function m($p0 = null, DateInterval $p1) {}
function n($p0 = null, $p1) {}

<?php

class A {
    function f(A $p) {}
}

class B extends A {
    function f(B $p) {}
}

<?php
function f($p0, DateInterval $p1 = null) {}
function g(DateInterval $p0 = null, $p1) {}
function j(DateInterval $p0 = null, $p1 = null) {}
function k($p0 = null, DateInterval $p1 = null) {}
function m($p0 = null, DateInterval $p1) {}
function n($p0 = null, $p1) {}