Doc #77321 [Nab]: array_filter combined with references

Edit report at https://bugs.php.net/bug.php?id=77321&edit=1 ID: 77321 Updated by: cmb@php.net Reported by: php at kingsquare dot nl Summary: array_filter combined with references Status: Not a bug Type: Documentation Problem Package: Arrays related PHP Version: 7.0.0 Block user comment: N Private report: N New Comment: Ah, of course. Thanks! Previous Comments: ------------------------------------------------------------------------ [2018-12-21 01:07:39] requinix@php.net I don't think there should be. As far as I know the callback is being called with a reference correctly, however for $input to get the change, it (being the first argument to array_filter) would have to be a reference too. Just like with a userland implementation, the by-ref $value is working, but since $input isn't a reference the change is happening on a copy. So no warning. Also like a userland implementation, you can trick the engine by making $input's items references to something else. $input is still a copy but changing $value will work. Like $source = [1, 2]; $input = [&$source[0], &$source[1]]; or foreach ($source as $key => $value) { $input[$key] =& $source[$key]; } ------------------------------------------------------------------------ [2018-12-20 23:40:35] cmb@php.net Shouldn't we trigger a notice/warning, if we ignore a call-by-ref declaration? ------------------------------------------------------------------------ [2018-12-20 16:56:55] requinix@php.net array_filter never supported by-ref values. The fact that it worked in PHP 5 was a bug, and it was fixed in PHP 7 when much of the engine changed. ------------------------------------------------------------------------ [2018-12-20 09:06:12] php at kingsquare dot nl Description: ------------ This is probably on purpose, but there is an undocumented backwards compatibility issue betwee PHP5 and PHP7. I know this might be a bit late to the party, but still. It involves the differnce in using array_filter and references. Test script: --------------- <?php // also see https://3v4l.org/Z2HnL $input = [1, 2]; var_dump(array_filter($input, function(& $value) { if ($value % 2 === 0) { return false; } $value++; return true; })); Expected result: ---------------- As the changelog doesn't seem to mention anything related to this I would expect them to be the same result [(int)2]. Actual result: -------------- PHP5: [2] PHP7: [1] ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=77321&edit=1