Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

If you comment out the __call magic you'll get pretty clear error message why and what goes wrong.

If i uncomment Bar::__call, i get the text "foobar" and not "__called!" or any other error. That is how 5.2.11 (not tried another version) handles it here currently.. I will try others later.

So, if self:: does rely on the scope of the object we came from (because we have NOT defined the function as static), Foo::__call should never be called if self:: or $this is used in Foo, or am i wrong?

It is something like PHP uses Bar::__call if it exists and if not Foo::__call(), hence we are not extending the class...

Output if Bar::__call commented: "foobar"
Output if Bar::__call uncommented: "__called!"

No, that is NOT BOGUS i think, there is something went wrong, and it took me quite a while finding the error in the app (using strace etc), and quite a while yet to reproduce this behavior with a small code snippet that will SEGFAULT. 

Note: Currently only tested on 5.2.11 and 5.2.0-8+etch15

Reproduce code:
---------------

<?php
class Foo
{
	function __call($f,$a)
	{
		echo("__call activated on class: ".__CLASS__.PHP_EOL);
	}
	function write($text) {
		echo( 'Foo: '.$text.PHP_EOL );
	}
	function debug($text) {
		return call_user_func_array(
			array(self,'write'),
			array($text,1)
		);
	}
}

class Bar {
	function __construct()
	{
		Foo::debug("foobar");
	}
}

class Baz {
	function __construct()
	{
		Foo::debug("foobar");
	}
	// here he dies...
	function __call($f,$a)
	{
		echo("__call activated on class: ".__CLASS__.PHP_EOL);
	}
}

$bar = new Bar();
$baz = new Baz(); // will cause php to die
?>

Expected result:
----------------
1. Calling non-static function Foo::debug() in Bar::__construct() 
a) should throw an function not found error while "self::" is used, as the engine does a lookup in Bar and does not find any function.
b) should not make the usage of Foo::__call() as it does not interact in the scope of Class Foo finally?

2. Calling Foo::debug() in Baz::__construct() in Baz::__construct()
a) should use __call as it is defined in Baz, and should rely on the scope of this class and not the non static called class Foo.. Uncomment Foo::__call to let the whole thing get more weird, as the text "Baz::foobar" is normally echoed if Baz::__call is only defined there (only defined!)
b) should never make the usage of Foo::call() as it does not interact in the scope of Class Foo finally?

Actual result:
--------------
dkr@*:~$ php test.php
__call activated on class: Foo
Segmentation fault
dkr@*:~$

Actual result without Foo::__call():
------------------------------------
dkr@*:~$ php phptest.php
PHP Warning:  call_user_func_array(): Unable to call self::write() in * on line *
Foo: foobar
dkr@*:~$

__call activated on class: Foo

Warning: String is not zero-terminated (ZZZZZZ���) (source: /home/felipe/dev/php5_2/Zend/zend_execute_API.c:414) in /home/felipe/dev/bug.php on line 15
[Tue Dec  8 14:59:22 2009]  Script:  '../bug.php'
---------------------------------------
/home/felipe/dev/php5_2/Zend/zend_execute_API.c(414) : Block 0x08b757f0 status:
/home/felipe/dev/php5_2/Zend/zend_variables.c(35) : Actual location (location was relayed)
Beginning:  	Cached
Freed (invalid)
    Start:	OK
      End:	OK
---------------------------------------
Foo: foobar
[Tue Dec  8 14:59:22 2009]  Script:  '../bug.php'
/home/felipe/dev/php5_2/Zend/zend_object_handlers.c(767) :  Freeing 0x08B75B80 (44 bytes), script=../bug.php
[Tue Dec  8 14:59:22 2009]  Script:  '../bug.php'
/home/felipe/dev/php5_2/Zend/zend_object_handlers.c(775) :  Freeing 0x08B75E7C (6 bytes), script=../bug.php
=== Total 2 memory leaks detected ===

Hm, i just think that this is an endless loop that should throw any error like "max function nesting reached" or something. The following codes are 2 easier examples that will fault:

Reproduce code #1:
------------------
<?php
class Foo {
	static function __call($f,$a) {
		static $call = 0;
		test();
	}
}
function test() {
	call_user_func_array(array('Foo','__call'),array(0,array()));
}
test();
?>

Reproduce code #2:
------------------
<?php
function Bar() {
	Foo();
}
function Foo() {
	Bar();
}
Foo();
?>

Expected result:
----------------
Fatal Error: Maximum calls of nested functions reached in ... on line ...

Actual result:
--------------
Segmentation fault

On Windows XP SP3 I've got the following output (I've switched error reporting to E_ALL):
Notice: Use of undefined constant self - assumed 'self' in C:\xampp\htdocs\test3.php on line 49
foobar

It looks already fixed.