#31525 [Opn]: object reference being dropped. $this getting lost.

ID: 31525 User updated by: yml at yml dot com Reported By: yml at yml dot com Status: Open Bug Type: Zend Engine 2 problem Operating System: * PHP Version: 5CVS-2005-03-03 New Comment: Problem found. Removing all the ()'s from reference returning functions and the problem has completely disappeared. However, the case should be caught by the parser and a warning generated. Using parens around returns returning references will cause symbol table corruption occassionally ... Previous Comments: ------------------------------------------------------------------------ [2005-03-06 02:43:51] michaels at crye-leike dot com True, if getThis() is declared to return a reference then everything works as expected. However, looking through the original reproduce code I noticed something else. If you add parentheses around $this in getThis() then the unexpected behavior returns. Complete code: <?php class Foo { function &getThis() { return ($this); } function destroyThis() { $baz =& $this->getThis(); } } $bar = new Foo(); $bar->destroyThis(); var_dump($bar); ?> Produces: NULL Expected: object(Foo)#1 (0) { } ------------------------------------------------------------------------ [2005-03-06 01:50:27] yml at yml dot com Unfortunately the shortened script works as it should if you declare getThis to return a reference as in function &getThis() If however, you refer to the "too-long" script I put together at: http://www.formvista.com/uploaded_files/php5_drops_object.php.txt There is something different about it that causes $this to get dropped even when the method is declared return-by-reference. I haven't been able to narrow it down but it's entirely possible I'm overlooking something obvious. It's got to be something related to legacy pass by reference notation =&. The strange thing is it worked in 5.0.1 and broke in 5.0.2 or .3. ------------------------------------------------------------------------ [2005-03-06 01:26:05] michaels at crye-leike dot com FWIW, here's a shorter script that reproduces the problem for me on PHP 5.0.3: <?php class Foo { function getThis() { return $this; } function destroyThis() { $baz =& $this->getThis(); } } $bar = new Foo(); $bar->destroyThis(); var_dump($bar); ?> This outputs: NULL If I change the assign-by-reference operator (=&) to the normal assignment operator (=) inside destroyThis(), I get: object(Foo)#1 (0) { } Hope this helps... ------------------------------------------------------------------------ [2005-03-03 18:32:24] yml at yml dot com 1. Same problem. No improvement. $this is getting dropped. Used to work in 5.0RC2. Since 5.0.3 it's been broken. 2. The script I sent was puny. Given how terribly buggy the Zend engine is, expecting that all serious parser errors can be reproduced in a total of 20 lines or less is ridiculous. The meat of the script I sent clearly reproduces the problem in 8 lines, not including the supporting classes. You guys wouldn't pull it from my site; and now you won't look at it if I send it to you. Exactly what would you propose I do to help you track this down? The 85,000 lines of code that's actually having this problem (and producing a coredump), now that's a huge "script". ------------------------------------------------------------------------ [2005-02-28 21:10:16] sniper@php.net Please try using this CVS snapshot: http://snaps.php.net/php5-latest.tar.gz For Windows: http://snaps.php.net/win32/php5-win32-latest.zip ..and NEVER ever attach such HUGE scripts in your report!!!! ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/31525 -- Edit this bug report at http://bugs.php.net/?id=31525&edit=1