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Bug #52133 Functions cannot return an argument passed by reference as reference
Submitted: 2010-06-21 13:56 UTC Modified: 2010-07-04 15:48 UTC
From: bschussek at gmail dot com Assigned: dmitry (profile)
Status: Not a bug Package: Scripting Engine problem
PHP Version: 5.3.2 OS: Linux Ubuntu 10.04
Private report: No CVE-ID: None
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 [2010-06-21 13:56 UTC] bschussek at gmail dot com 
Description:
------------
PHP does not behave as expected when passing arguments by reference into a 
function that are passed out again by reference.

IMO, the below test script should behave equivalently to the following code 
(which produces the expected result):

$b = 'foobar';
$a =& $b;
$c =& $a;
$c[2] = 'z';

var_dump($c);
var_dump($b);

Test script:
---------------
function &ref(&$a)
{
  return $a;
}

$b = 'foobar';
$c = ref($b);
$c[2] = 'z';

Expected result:
----------------
string 'fozbar' (length=6)
string 'fozbar' (length=6)

Actual result:
--------------
string 'fozbar' (length=6)
string 'foobar' (length=6)

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 [2010-06-23 00:29 UTC] johannes@php.net
-Status: Open +Status: Feedback
 [2010-06-23 00:29 UTC] johannes@php.net 
Please try using this snapshot:

  http://snaps.php.net/php5.3-latest.tar.gz
 
For Windows:

  http://windows.php.net/snapshots/
 [2010-06-23 00:48 UTC] bschussek at gmail dot com
-Status: Feedback +Status: Open
 [2010-06-23 00:48 UTC] bschussek at gmail dot com 
Sorry, but the test script produces still the wrong output for me.

$ php -v
PHP 5.3.3-dev (cli) (built: Jun 23 2010 00:45:57) 
Copyright (c) 1997-2010 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies
    with Xdebug v2.0.5, Copyright (c) 2002-2008, by Derick Rethans

$ php test.php
string(6) "foobar"
string(6) "fozbar"
 [2010-06-23 00:51 UTC] bschussek at gmail dot com 
In my last comment I dumped first $b and then $c, so the output hasn't changed 
from PHP 5.3.2.
 [2010-06-23 00:56 UTC] johannes@php.net
-Status: Open +Status: Assigned -Assigned To: +Assigned To: dmitry
 [2010-06-23 09:31 UTC] dmitry@php.net
-Status: Assigned +Status: Bogus
 [2010-06-23 09:31 UTC] dmitry@php.net 
You forgot "&" in assignment.

$c =& ref($b);
 [2010-07-04 15:48 UTC] bschussek at gmail dot com 
Thanks, that's right. Maybe this error message should be improved then?

"Strict standards: Only variables should be assigned by reference"

Obviously (which I didn't know, due to the error message) it is possible to 
assign functions by reference, but only if they are marked to return a reference.
 
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