# PHP7 / foreach / references / ugly code / discrepancy to PHP 5.6 - Thread: https://externals.io/message/89150 - Original archive: https://news-web.php.net/php.internals/89150 - Started by Philip Hofstetter on 2015-11-10T16:48:54+00:00 - Messages: 6 - Reply by email to internals@lists.php.net - More for agents: search with https://externals.io/search.md?q={query} · JSON API at https://externals.io/api · documentation at https://externals.io/llms.txt --- ## #89150 — Philip Hofstetter — 2015-11-10T16:48:54+00:00 URL: https://externals.io/message/89150#89150 Hi, I'm having a cause of slightly ugly code that runs differently from PHP 5.6 to PHP 7 and I don't think this difference is documented, nor expected. As I'm not sure whether this is an intended change or not, I'm asking here firstr before making a bug report. The code in question is ---- $b = [1, 2, 3]; foreach($b ?: [] as &$v){ $v = $v*2; unset($v); } var_dump($b); ---- in PHP7, this produces array(3) { [0] => int(1) [1] => int(2) [2] => int(3) } whereas in PHP 5.6 and earlier, this produces array(3) { [0] => int(2) [1] => int(4) [2] => int(6) } what scares me about this is that in order to get the old behaviour in PHP7 back, you just have to get rid of the ?: operator: foreach($b as &$v){ is fine foreach($b ?: [] as &$v){ is not. I guess this is related to http://php.net/manual/en/migration70.incompatible.php#migration70.incompatible.foreach.by-value or http://php.net/manual/en/migration70.incompatible.php#migration70.incompatible.foreach.by-ref, but I'm not entirely sure whether this is actually intended behaviour - it's certainly unexpected to me that applying ?: now always makes a copy whereas before it didn't. Philip -- Sensational AG Giesshübelstrasse 62c, Postfach 1966, 8021 Zürich Tel. +41 43 544 09 60, Mobile +41 79 341 01 99 info@sensational.ch, http://www.sensational.ch --- ## #89152 — Martin Amps — 2015-11-10T19:08:55+00:00 URL: https://externals.io/message/89150#89152 · In reply to: #89150 Here’s a 3v4l demonstrating this too: https://3v4l.org/OXAd3 > > > Hi, > > I'm having a cause of slightly ugly code that runs differently from PHP 5.6 > to PHP 7 and I don't think this difference is documented, nor expected. As > I'm not sure whether this is an intended change or not, I'm asking here > firstr before making a bug report. > > The code in question is > > ---- > $b = [1, 2, 3]; > > foreach($b ?: [] as &$v){ > $v = $v*2; > unset($v); > } > > var_dump($b); > ---- > in PHP7, this produces > > array(3) { > [0] => > int(1) > [1] => > int(2) > [2] => > int(3) > } > > whereas in PHP 5.6 and earlier, this produces > > array(3) { > [0] => > int(2) > [1] => > int(4) > [2] => > int(6) > } > > what scares me about this is that in order to get the old behaviour in PHP7 > back, you just have to get rid of the ?: operator: > > foreach($b as &$v){ > > is fine > > foreach($b ?: [] as &$v){ > > is not. > > I guess this is related to > http://php.net/manual/en/migration70.incompatible.php#migration70.incompatible.foreach.by-value > or > http://php.net/manual/en/migration70.incompatible.php#migration70.incompatible.foreach.by-ref, > but I'm not entirely sure whether this is actually intended behaviour - > it's certainly unexpected to me that applying ?: now always makes a copy > whereas before it didn't. > > Philip > > > > -- > Sensational AG > Giesshübelstrasse 62c, Postfach 1966, 8021 Zürich > Tel. +41 43 544 09 60, Mobile +41 79 341 01 99 > info@sensational.ch, http://www.sensational.ch --- ## #89154 — Bishop Bettini — 2015-11-10T19:31:32+00:00 URL: https://externals.io/message/89150#89154 · In reply to: #89150 On Tue, Nov 10, 2015 at 11:48 AM, Philip Hofstetter < phofstetter@sensational.ch> wrote: > Hi, > ...snip... > I guess this is related to > > http://php.net/manual/en/migration70.incompatible.php#migration70.incompatible.foreach.by-value > or > > http://php.net/manual/en/migration70.incompatible.php#migration70.incompatible.foreach.by-ref > , > but I'm not entirely sure whether this is actually intended behaviour - > it's certainly unexpected to me that applying ?: now always makes a copy > whereas before it didn't. > The issue may not be with foreach, but instead with the ?: ternary or the optimizer. Maybe either: 1. It's a side-effect of merging the ZEND_QM_ASSIGN and ZEND_QM_ASSIGN_VAR op codes. (See PHP 5.6 ?: op code definitions and Same for PHP 7.0 .) 2. The optimizer isn't handling the foreach scenario. (See Block pass optimizer code .) I don't see any change notes for either, so I'm guessing this is a bug. bishop --- ## #89155 — Nikita Popov — 2015-11-10T19:45:07+00:00 URL: https://externals.io/message/89150#89155 · In reply to: #89150 On Tue, Nov 10, 2015 at 5:48 PM, Philip Hofstetter < phofstetter@sensational.ch> wrote: > Hi, > > I'm having a cause of slightly ugly code that runs differently from PHP 5.6 > to PHP 7 and I don't think this difference is documented, nor expected. As > I'm not sure whether this is an intended change or not, I'm asking here > firstr before making a bug report. > > The code in question is > > ---- > $b = [1, 2, 3]; > > foreach($b ?: [] as &$v){ > $v = $v*2; > unset($v); > } > > var_dump($b); > ---- > in PHP7, this produces > > array(3) { > [0] => > int(1) > [1] => > int(2) > [2] => > int(3) > } > > whereas in PHP 5.6 and earlier, this produces > > array(3) { > [0] => > int(2) > [1] => > int(4) > [2] => > int(6) > } > > what scares me about this is that in order to get the old behaviour in PHP7 > back, you just have to get rid of the ?: operator: > > foreach($b as &$v){ > > is fine > > foreach($b ?: [] as &$v){ > > is not. > > I guess this is related to > > http://php.net/manual/en/migration70.incompatible.php#migration70.incompatible.foreach.by-value > or > > http://php.net/manual/en/migration70.incompatible.php#migration70.incompatible.foreach.by-ref > , > but I'm not entirely sure whether this is actually intended behaviour - > it's certainly unexpected to me that applying ?: now always makes a copy > whereas before it didn't. > This is a bug in PHP 5, which has been fixed in PHP 7 as a side-effect of other changes. The new behavior is correct. This issue is tracked at https://bugs.php.net/bug.php?id=70857. Nikita --- ## #89156 — Adam Harvey — 2015-11-10T19:47:31+00:00 URL: https://externals.io/message/89150#89156 · In reply to: #89155 Hey Nikita, > This is a bug in PHP 5, which has been fixed in PHP 7 as a side-effect of > other changes. The new behavior is correct. This issue is tracked at > https://bugs.php.net/bug.php?id=70857. Are there any other variations on what expressions this changes the behaviour of, or is it really just ternaries? Just trying to figure out how to document this. Thanks, Adam --- ## #89177 — David Zuelke — 2015-11-11T13:33:49+00:00 URL: https://externals.io/message/89150#89177 · In reply to: #89155 Should this be in the UPGRADING notes? > > > On Tue, Nov 10, 2015 at 5:48 PM, Philip Hofstetter < > phofstetter@sensational.ch> wrote: > > > […] > > This is a bug in PHP 5, which has been fixed in PHP 7 as a side-effect of > other changes. The new behavior is correct. This issue is tracked at > https://bugs.php.net/bug.php?id=70857. > > Nikita