Bug #81072 [NoF->Opn]: Incorrect behavior of DateTime->modify across DST changes

Edit report at https://bugs.php.net/bug.php?id=81072&edit=1 ID: 81072 Updated by: requinix@php.net Reported by: ph-bugs at allenjb dot me dot uk Summary: Incorrect behavior of DateTime->modify across DST changes -Status: No Feedback +Status: Open Type: Bug Package: Date/time related PHP Version: 8.0.6 Block user comment: N Private report: N Previous Comments: ------------------------------------------------------------------------ [2021-05-30 04:22:13] php-bugs at lists dot php dot net No feedback was provided. The bug is being suspended because we assume that you are no longer experiencing the problem. If this is not the case and you are able to provide the information that was requested earlier, please do so and change the status of the bug back to "Re-Opened". Thank you. ------------------------------------------------------------------------ [2021-05-23 09:45:58] php-bugs at allenjb dot me dot uk I've tested this with current master (8.1-dev) and the issue still exists. I noticed a bug in the reproduction script I previously posted and have fixed it. Updated script: https://3v4l.org/01oD9 <?php function incrementWithSwitch($date, $invert) { $timezone = $date->getTimezone(); $date = $date->setTimezone(new DateTimeZone('UTC')); $date = $date->modify(($invert ? '-' : '+') . '1 hour'); $date = $date->setTimezone($timezone); $date = $date->setTime((int)$date->format('H'), 0); return $date; } function incrementWithoutSwitch($date, $invert) { $date = $date->modify(($invert ? '-' : '+') . '1 hour'); return $date; } $tz = new \DateTimeZone("Europe/London"); $dtWith = \DateTimeImmutable::createFromFormat("!Y-m-d H:i:s", "2021-03-28 04:00:00", $tz); $dtWithout = $dtWith; $invert = true; for ($i = 0; $i < 4; $i++) { print "\nRound {$i}:"; $dtWith = incrementWithSwitch($dtWith, $invert); $dtWithout = incrementWithoutSwitch($dtWithout, $invert); print "With switch: ". $dtWith->format(\DateTime::RFC3339); print " :: Without switch: ". $dtWithout->format(\DateTime::RFC3339); } print "\n---\n"; $dtWith = \DateTimeImmutable::createFromFormat("!Y-m-d H:i:s", "2021-03-28 00:00:00"); $dtWithout = $dtWith; $invert = false; for ($i = 0; $i < 4; $i++) { print "\nRound {$i}:"; $dtWith = incrementWithSwitch($dtWith, $invert); $dtWithout = incrementWithoutSwitch($dtWithout, $invert); print "With switch: ". $dtWith->format(\DateTime::RFC3339); print " :: Without switch: ". $dtWithout->format(\DateTime::RFC3339); } ------------------------------------------------------------------------ [2021-05-22 20:17:54] requinix@php.net Looks like 3v4l.org is behind a few versions - maybe was impacted by the GitHub move. I can't reproduce locally. Can you test in current master (8.1)? If it works there then this may be a duplicate of 74274. ------------------------------------------------------------------------ [2021-05-22 18:55:52] ph-bugs at allenjb dot me dot uk Description: ------------ See https://3v4l.org/hGXcr Working on a fix for https://github.com/dragonmantank/cron-expression/issues/111 As you can see, when working backwards with ->modify("-1 hour") DateTime fails to properly handle the DST change and keeps pushing the time forward to 03:00:00 Working forwards with ->modify("+1 hour") does not exhibit the same behavior. (The code examples also show a workaround, which involved switching timezones while performing the ->modify) Test script: --------------- <?php function incrementWithSwitch($date, $invert) { $timezone = $date->getTimezone(); $date = $date->setTimezone(new DateTimeZone('UTC')); $date = $date->modify(($invert ? '-' : '+') . '1 hour'); $date = $date->setTimezone($timezone); $date = $date->setTime((int)$date->format('H'), 0); return $date; } function incrementWithoutSwitch($date, $invert) { $date = $date->modify(($invert ? '-' : '+') . '1 hour'); return $date; } $tz = new \DateTimeZone("Europe/London"); $dtWith = \DateTimeImmutable::createFromFormat("!Y-m-d H:i:s", "2021-03-28 04:00:00"); $dtWithout = $dtWith; $invert = true; for ($i = 0; $i < 3; $i++) { print "\nRound {$i}:"; $dtWith = incrementWithSwitch($dtWith, $invert); $dtWithout = incrementWithoutSwitch($dtWithout, $invert); print "With switch: ". $dtWith->format(\DateTime::RFC3339); print " :: Without switch: ". $dtWithout->format(\DateTime::RFC3339); } print "\n---\n"; $dtWith = \DateTimeImmutable::createFromFormat("!Y-m-d H:i:s", "2021-03-28 00:00:00"); $dtWithout = $dtWith; $invert = false; for ($i = 0; $i < 3; $i++) { print "\nRound {$i}:"; $dtWith = incrementWithSwitch($dtWith, $invert); $dtWithout = incrementWithoutSwitch($dtWithout, $invert); print "With switch: ". $dtWith->format(\DateTime::RFC3339); print " :: Without switch: ". $dtWithout->format(\DateTime::RFC3339); } Expected result: ---------------- Round 0:With switch: 2021-03-28T03:00:00+02:00 :: Without switch: 2021-03-28T03:00:00+02:00 Round 1:With switch: 2021-03-28T01:00:00+01:00 :: Without switch: 2021-03-28T01:00:00+02:00 Round 2:With switch: 2021-03-28T00:00:00+01:00 :: Without switch: 2021-03-28T00:00:00+02:00 --- Round 0:With switch: 2021-03-28T01:00:00+01:00 :: Without switch: 2021-03-28T01:00:00+01:00 Round 1:With switch: 2021-03-28T03:00:00+02:00 :: Without switch: 2021-03-28T03:00:00+02:00 Round 2:With switch: 2021-03-28T04:00:00+02:00 :: Without switch: 2021-03-28T04:00:00+02:00 Actual result: -------------- Round 0:With switch: 2021-03-28T03:00:00+02:00 :: Without switch: 2021-03-28T03:00:00+02:00 Round 1:With switch: 2021-03-28T01:00:00+01:00 :: Without switch: 2021-03-28T03:00:00+02:00 Round 2:With switch: 2021-03-28T00:00:00+01:00 :: Without switch: 2021-03-28T03:00:00+02:00 --- Round 0:With switch: 2021-03-28T01:00:00+01:00 :: Without switch: 2021-03-28T01:00:00+01:00 Round 1:With switch: 2021-03-28T03:00:00+02:00 :: Without switch: 2021-03-28T03:00:00+02:00 Round 2:With switch: 2021-03-28T04:00:00+02:00 :: Without switch: 2021-03-28T04:00:00+02:00 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=81072&edit=1