php.net |  support |  documentation |  report a bug |  advanced search |  search howto |  statistics |  random bug |  login

go to bug id or search bugs for

Bug #33643 Fatal error: Only variables can be passed by reference
Submitted: 2005-07-11 13:06 UTC Modified: 2005-08-16 21:04 UTC
Votes:145
Avg. Score:4.5 ± 0.9
Reproduced:133 of 133 (100.0%)
Same Version:57 (42.9%)
Same OS:57 (42.9%)
From: Jason at hybd dot net Assigned:
Status: Wont fix Package: Scripting Engine problem
PHP Version: 4CVS-2005-07-18 OS: *
Private report: No CVE-ID: None
View Developer Edit
Welcome back! If you're the original bug submitter, here's where you can edit the bug or add additional notes.
If you forgot your password, you can retrieve your password here.
Password:
Status:
Package:
Bug Type:
Summary:
From: Jason at hybd dot net
New email:
PHP Version: OS:

 

 [2005-07-11 13:06 UTC] Jason at hybd dot net 
Description:
------------
This bug is a rehash of 33516, but I can't reopen as I'm not the original author.

It seems like you can not pass tempories to function / method parameters.

<?php

class Foo {
	public static function bar() {
		return array('a' => '1234567890');
	}
}

$tmp = Foo::bar();
$var = array_pop($tmp);

?>

Seems to work, but it shouldn't be down to the PHP user (imho) to implement this as this change in PHP 5.1 breaks a lot of existing code.

Reproduce code:
---------------
<?php

class Foo {
	public static function bar() {
		return array('a' => '1234567890');
	}
}

$var = array_pop(Foo::bar());

?>

Expected result:
----------------
$var = '1234567890';
Foo::bar() gets placed in temporary variable

Actual result:
--------------
Fatal error: Only variables can be passed by reference

Patches

Pull Requests

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2005-07-14 11:01 UTC] vrana@php.net 
Actual result (4.x after removing "public static"):

4.3.10: No error
4.4.0: No error
5.0.4: No error
5.1.0: Fatal error

Is this really the expected result? I thought 4.4.0 should produce something too. In which cases 4.4.0 produces errors?
 [2005-07-14 11:16 UTC] derick@php.net 
I think we need to discuss this a bit more, PHP 4.4 indeed gives no warning or notice on this. Andi, Dmitry?
 [2005-07-14 13:06 UTC] dmitry@php.net 
The "Fatal error:" in HEAD and PHP_5_0 occurs because of fix for bug #33257. The patch was not applied into PHP 4.4  because it wasn't affected by this bug (PHP 4 doesn't allow static properties).

Now I found reproducable case for PHP_4_4. :(

<?php
$x = array('foo');

function foo() {
	return $GLOBALS['x'];
}

function bar() {
	static $x = array('bar');
	return $x;
}

echo array_pop(foo())."\n";
echo array_pop(foo())."\n"; /* BUG */
echo array_pop(bar())."\n";
echo array_pop(bar())."\n";
?>
Expected result:
----------------
Fatal error: Only variables can be passed by reference 

Or:
---
foo
foo
bar
bar

Actual result:
--------------
foo

bar
bar


The current behavoir of HEAD is proper from my point of view. PHP_4_4 may be fixed but it will break BC again.

Derick, Andi?
 [2005-07-14 16:37 UTC] rasmus@php.net 
This sort of thing needs to throw an error in any version of PHP I think:

  function foo() { return "blah"; }
  function bar(&$arg) { $arg = 1; }
  bar(foo());

While this should work:

  function & foo() { static $a; return $a; }
  function bar(&$arg) { $arg = 1; }
  bar(foo());

And it does in PHP5.1 at least.  The first case indicates a clear bug in the code that we really should be catching.  I suppose we could compromise and throw a warning in PHP4 and then fall back to passing the argument by value, but that is changing the actual workings of the script and is likely going to be wrong.  I think this needs to be part of the reference fixes in PHP4.4.  Sucks that it wasn't caught before the 4.4.0 release, but that's the way it goes.
 [2005-08-16 21:04 UTC] derick@php.net 
This is not fixable in PHP 4.4 without breaking BC, so we can't fix it now. Luckily it does not create any memory corruption.
 
PHP Copyright © 2001-2025 The PHP Group
All rights reserved. 		Last updated: Sun Feb 16 14:01:31 2025 UTC