#35865 [NEW]: Undocumented change to behaviour of references

From: tigerincanada at gmail dot com Operating system: Linux 2.4.20 (Red Hat) PHP version: 4.4.1 PHP Bug Type: Class/Object related Bug description: Undocumented change to behaviour of references Description: ------------ After upgrading to PHP 4.4.1 I started seeing "Fatal error: Call to a member function on a non-object" where previously there had been none. It appears that the behaviour of references has changed, so the the reuse of a variable name no longer unassigns that variable name from earlier copies of the previous contents of that variable. The attempt at a reproduce code below doesn't actually cause the bug to reproduce, but illustrates the type of code that was causing the problem. I haven't worked out what feature of my more complex production code is causing the issue, but it wasn't there before upgrading to from 4.3.11 to 4.4.1. Googling "Fatal error: Call to a member function on a non-object PHP 4.4.1" shows up a few other people who appear to have run into a similar unexpected issue. Reproduce code: --------------- Class Foo { var $name; function Foo($n) { $this->name = $n; } function getName() { return $this->name; } } $result =& new Foo("First"); $c =& $result; $b = "Second"; $result =& $b; print $c->getName(); Expected result: ---------------- "First" Actual result: -------------- Attempted reproduce code: "First" Production code: "Fatal error: Call to a member function on a non-object" In production, querying the zval of $c finds that it has somehow been set to the value of on the the object's properties... major head-scratcher! When I changed the code to remove the variable re-use, like this: $c =& new Foo("First"); $b = "Second"; $result =& $b; The problem went away... -- Edit bug report at http://bugs.php.net/?id=35865&edit=1 -- Try a CVS snapshot (PHP 4.4): http://bugs.php.net/fix.php?id=35865&r=trysnapshot44 Try a CVS snapshot (PHP 5.1): http://bugs.php.net/fix.php?id=35865&r=trysnapshot51 Try a CVS snapshot (PHP 6.0): http://bugs.php.net/fix.php?id=35865&r=trysnapshot60 Fixed in CVS: http://bugs.php.net/fix.php?id=35865&r=fixedcvs Fixed in release: http://bugs.php.net/fix.php?id=35865&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=35865&r=needtrace Need Reproduce Script: http://bugs.php.net/fix.php?id=35865&r=needscript Try newer version: http://bugs.php.net/fix.php?id=35865&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=35865&r=support Expected behavior: http://bugs.php.net/fix.php?id=35865&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=35865&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=35865&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=35865&r=globals PHP 3 support discontinued: http://bugs.php.net/fix.php?id=35865&r=php3 Daylight Savings: http://bugs.php.net/fix.php?id=35865&r=dst IIS Stability: http://bugs.php.net/fix.php?id=35865&r=isapi Install GNU Sed: http://bugs.php.net/fix.php?id=35865&r=gnused Floating point limitations: http://bugs.php.net/fix.php?id=35865&r=float No Zend Extensions: http://bugs.php.net/fix.php?id=35865&r=nozend MySQL Configuration Error: http://bugs.php.net/fix.php?id=35865&r=mysqlcfg