Thank you for this bug report. To properly diagnose the problem, we
need a short but complete example script to be able to reproduce
this bug ourselves. 

A proper reproducing script starts with <?php and ends with ?>,
is max. 10-20 lines long and does not require any external 
resources such as databases, etc.

If possible, make the script source available online and provide
an URL to it here. Try to avoid embedding huge scripts into the report.

Umm. Check the script I put together for you at:

http://www.yml.com/homepage.html?COMP=clog_list&cmd=detail&cs_clog_entries_ref=149

If you have trouble accessing it please let me know.

Just a simple page with the script please, or paste it here.

I forgot to mention, check the few lines at the very bottom of the code. Unfortunately the class definitions are required to reproduce the error but the basic script is extremely simple.

Under PHP 5 you get a Warning: Attempt to assign property of non-object in /usr/local2/WWW/mobie.yml.com/mobie/admin_ui/tests/php_5_test/test.php on line 407

Under PHP 4 it runs through the 1000 iterations without fail.

It's very simple code. This code used to run in PHP 5.0, but something changed in later versions to cause this error to crop up.

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!!!!

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".

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...

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.

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) {
}

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 ...

Andi, I think you once responded to similar issue regarding return() with/without parenthesis..

Fixed in CVS HEAD and PHP_5_0.