Bug #70289 [Asn->Csd]: Different sort in php7 (and hhvm) compared to php5

Edit report at https://bugs.php.net/bug.php?id=70289&edit=1 ID: 70289 Updated by: cmb@php.net Reported by: kjarli at gmail dot com Summary: Different sort in php7 (and hhvm) compared to php5 -Status: Assigned +Status: Closed Type: Bug Package: Arrays related Operating System: Ubuntu 14.04 PHP Version: 7.0.0beta3 Assigned To: cmb Block user comment: N Private report: N New Comment: Automatic comment on behalf of cmb Revision: http://git.php.net/?p=php-src.git;a=commit;h=1b5e87a579080da1452e173981b7d8a6814f15c0 Log: Fix #70289: Different sort in php7 (and hhvm) compared to php5 Previous Comments: ------------------------------------------------------------------------ [2015-08-18 11:31:08] cmb@php.net I agree that a note in UPGRADING is appropriate, event though the documentation (e.g. for usort()) already states: | If two members compare as equal, their relative order in the | sorted array is undefined. See also the related internal discussion <http://markmail.org/thread/trb3g4o6vqccitpd>. ------------------------------------------------------------------------ [2015-08-18 08:22:39] kjarli at gmail dot com This report seems related: https://bugs.php.net/bug.php?id=40888 If it's not a bug and indeed related to small arrays in php7, I would rather see a small notice in the upgrade guide than to have people "waste" time on such a trivial "issue" as it's much better to rely on defined behavior by the developer. ------------------------------------------------------------------------ [2015-08-18 08:19:51] requinix@php.net 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 the script requires a database to demonstrate the issue, please make sure it creates all necessary tables, stored procedures etc. Please avoid embedding huge scripts into the report. Sounds like cweiske's right. PHP's sorting has never promised that equal elements will appear in any particular order. Also know that PHP 7 uses a different sorting algorithm for small arrays than it does larger arrays. ------------------------------------------------------------------------ [2015-08-18 08:14:40] cweiske@php.net I saw the same in the PEAR core unit tests. This only happens when the elements are equal. Since they are equal, the order of the elements is unspecified and dependent on the internal implementation and the sort algorithm. Not a bug in my eyes. ------------------------------------------------------------------------ [2015-08-18 08:08:13] kjarli at gmail dot com Description: ------------ I haven't gotten a proper test setup, but I do have the travis builds. I was working on a priority sorting feature and I had added a test to verify sort orders. On php5 it consistently went right, but on php7 and hhvm it was in reversed order. I fixed it by adding a secondary sort (strcmp). Build #45 (failed): https://travis-ci.org/iltar/http-bundle/builds/76059069 Build #46 (failed): https://travis-ci.org/iltar/http-bundle/builds/76061283 Build #47 (fixed): https://travis-ci.org/iltar/http-bundle/builds/76062321 The test in question: https://github.com/iltar/http-bundle/blob/feature/property-accessor/test/DependencyInjection/DecorateRouterPassTest.php#L72-L112 It's about the one with a priority of 50, which is reversed as you can see in the failed output. Test script: --------------- https://github.com/iltar/http-bundle/blob/feature/property-accessor/test/DependencyInjection/DecorateRouterPassTest.php#L72-L112 Expected result: ---------------- I expect to see consistent sorting, but that was not the case. sequence: app.henk2_50 app.henk_50 Actual result: -------------- sequence: app.henk_50 app.henk2_50 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=70289&edit=1