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

go to bug id or search bugs for

Doc Bug #73267 Order by callback changed
Submitted: 2016-10-07 21:21 UTC Modified: 2016-10-18 14:58 UTC
From: me at evertpot dot com Assigned: cmb (profile)
Status: Closed Package: Arrays related
PHP Version: 7.1.0RC3 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: me at evertpot dot com
New email:
PHP Version: OS:

 

 [2016-10-07 21:21 UTC] me at evertpot dot com 
Description:
------------
Hey guys,

I noticed one of my unittests failing on PHP 7.1. Took me a bit to figure out what was going on, but ended up figuring out that if you sort-by-callback, PHP 7.1 has a different order.

The use-case might sound a bit weird, and I'm certainly not suggesting that this is a bug. I merely wanted to suggest that maybe this might be added to the "Backwards compatibility changed" document. 

Test script:
---------------
https://3v4l.org/DWujs


<?php

$foo = [1,1];
$bar = [
   function() use (&$k) {
      echo "first!";
   },
   function() use (&$k) {
      echo "second!";
   },
];

array_multisort($foo, SORT_NUMERIC, $bar);

$bar[0]();

?>

Patches

Pull Requests

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2016-10-08 09:10 UTC] cmb@php.net
-Type: Bug +Type: Documentation Problem -Package: Documentation problem +Package: Arrays related -Assigned To: +Assigned To: cmb
 [2016-10-08 09:10 UTC] cmb@php.net 
Indeed, the sorting order has changed, but that is an
implementation detail that should not be relied upon anyway,
because:

| If two members compare as equal, their relative order in the
| sorted array is undefined.

That's already documented for all? other sorting functions, but
has been forgotten for array_multisort().

Adding a note to the changelog or migration guide regarding a
behavioral change of undefined behavior wouldn't make sense (the
behavior is still undefined).
 [2016-10-08 09:12 UTC] cmb@php.net 
Automatic comment from SVN on behalf of cmb
Revision: http://svn.php.net/viewvc/?view=revision&amp;revision=340377
Log: Fix #73267: Order by callback changed
 [2016-10-08 09:12 UTC] cmb@php.net
-Status: Assigned +Status: Closed
 [2016-10-08 15:23 UTC] me at evertpot dot com 
Hi cmb,

Thanks for the quick change. I definitely meant to mark it as a "documentation bug" but somehow that setting got lost.

I actually have a simpler test-case that demonstrates that it's not just equality of identical values:

https://3v4l.org/kH84K

It was a bit late yesterday, so I didn't catch this.

Now the result of this function might also (as you said) "undefined", and I readily admit that my unittest was wrong assuming a certain output, but it might still be a nice courtesy to include it in the migration documentation. Of course you can include in that document that relying on a sort order in the first place was wrong.
 [2016-10-18 14:58 UTC] cmb@php.net 
I've noticed that the 7.0 UPGRADING has a respective note[1], so
it appears to be okay to also add notes to the 7.0 and 7.1
migration guides.

> I definitely meant to mark it as a "documentation bug" but
> somehow that setting got lost.

That's a nasty bug of the bug tracker. Previewing discards any
changes to the "Bug Type".

[1] <https://github.com/php/php-src/blob/PHP-7.0.12/UPGRADING#L434-L435>
 [2016-10-18 14:58 UTC] cmb@php.net 
Automatic comment from SVN on behalf of cmb
Revision: http://svn.php.net/viewvc/?view=revision&amp;revision=340557
Log: Fix #73267: Order by callback changed

While users are not supposed to rely on a stable sort anyway, it
may be helpful to explicitly mention possible sort order changes
in the migration guides.
 [2016-10-20 23:28 UTC] me at evertpot dot com 
Thank, that's really awesome!
 [2020-02-07 06:06 UTC] phpdocbot@php.net 
Automatic comment on behalf of cmb
Revision: http://git.php.net/?p=doc/en.git;a=commit;h=e1a00d71720c1d76b925283125eb544b716b10e8
Log: Fix #73267: Order by callback changed
 [2020-02-07 06:06 UTC] phpdocbot@php.net 
Automatic comment on behalf of cmb
Revision: http://git.php.net/?p=doc/en.git;a=commit;h=5c65942664074e1a707e89fbc6887860287d60e9
Log: Fix #73267: Order by callback changed
 
PHP Copyright © 2001-2026 The PHP Group
All rights reserved. 		Last updated: Thu Oct 08 15:00:02 2026 UTC