This is really a tough one,  think about following:

<?php
class Foo {

public function setSelf(self $s) { }

}

class Bar extends Foo {

public function setSelf(parent $s) { }

}
?>
---------------------
<?php
class Foo {

public function setSelf(Foo $s) { }

}

class Bar extends Foo {

public function setSelf(parent $s) { }

}
-----------------------
<?php
class Base {
}

class Foo extends Base{

public function setSelf(parent $s) { }

}

class Bar extends Foo {

public function setSelf(Base $s) { }

}


and more.......

I have a patch now, will apply it after do careful testings

a patch for php 5.4 was submitted, since 5.4 will generate detailed info about the 
prototype argument list, so this defect is more significant for 5.4.

and Tyrael suggest commit this only after 5.4.0 release. so leave this open, I 
will commit later.

thanks

This bug has been fixed in SVN.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.

 For Windows:

http://windows.php.net/snapshots/
 
Thank you for the report, and for helping us make PHP better.

This patch seems to cause strange behaviour for interfaces. If the "self" keyword is defined in an interface, I would think that "self" would refer to the implementing class.

Test script which worked in 5.3.19:

<?php

interface Comparable
{
    function compare(self $compare);
}

// Which is then implemented:

class Foo implements Comparable
{
    function compare(self $compare)
    {}
}

class Bar implements Comparable
{
    function compare(self $compare)
    {}
}

$foo = new Foo();
$bar = new Bar();

$foo->compare($foo);
$bar->compare($bar);