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

Edit report at https://bugs.php.net/bug.php?id=81072&edit=1 ID: 81072 Comment by: antonino dot spampinato86 at gmail dot com Reported by: ph-bugs at allenjb dot me dot uk Summary: Incorrect behavior of DateTime->modify across DST changes Status: Open Type: Bug Package: Date/time related PHP Version: 8.0.6 Block user comment: N Private report: N New Comment: Sorry change $dtWithout_test1 = incrementWithoutSwitch($dtWithout, $invert); to $dtWithout = incrementWithoutSwitch($dtWithout, $invert); The bug is there, the expected result is not obtained. :-) Previous Comments: ------------------------------------------------------------------------ [2021-07-30 10:43:46] antonino dot spampinato86 at gmail dot com This is the refined version proposed. DST transition bug for modify function exists. Bug 74224 mentions that from php 8.1 that diff function has been changed and supports time not conversion to UTC and this makes time or date calculations consistent with local time. Actually diff function also suffers from DST or ST problems, If you deem it necessary I will also show it to you. function incrementWithSwitch($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; $string = 'Start ' . $dtWith->format('Y-m-d H:i:s Z') . PHP_EOL; for ($i = 0; $i < 4; $i++) { $string .= "Round {$i}: "; $dtWith = incrementWithSwitch($dtWith, $invert); $dtWithout_test1 = incrementWithoutSwitch($dtWithout, $invert); $string .= 'With switch: ' . $dtWith->format('Y-m-d H:i:s Z'); $string .= ' :: Without switch: '. $dtWithout->format('Y-m-d H:i:s Z') . PHP_EOL; } $string .= '---' . PHP_EOL; $dtWith = \DateTimeImmutable::createFromFormat('!Y-m-d H:i:s', '2021-03-27 23:00:00', $tz); $dtWithout = $dtWith; $invert = false; $string .= 'Start ' . $dtWith->format('Y-m-d H:i:s Z') . PHP_EOL; for ($i = 0; $i < 4; $i++) { $string .= "Round {$i}: "; $dtWith = incrementWithSwitch($dtWith, $invert); $dtWithout = incrementWithoutSwitch($dtWithout, $invert); $string .= 'With switch: ' . $dtWith->format('Y-m-d H:i:s Z'); $string .= ' :: Without switch: ' . $dtWithout->format('Y-m-d H:i:s Z') . PHP_EOL; } print($string); Expected: Start 2021-03-28 04:00:00 3600 Round 0: With switch: 2021-03-28 03:00:00 3600 :: Without switch: 2021-03-28 03:00:00 3600 Round 1: With switch: 2021-03-28 02:00:00 3600 :: Without switch: 2021-03-28 02:00:00 3600 Round 2: With switch: 2021-03-28 00:00:00 0 :: Without switch: 2021-03-28 00:00:00 3600 Round 3: With switch: 2021-03-27 23:00:00 0 :: Without switch: 2021-03-27 23:00:00 3600 --- Start 2021-03-27 23:00:00 0 Round 0: With switch: 2021-03-28 00:00:00 0 :: Without switch: 2021-03-28 00:00:00 0 Round 1: With switch: 2021-03-28 02:00:00 3600 :: Without switch: 2021-03-28 02:00:00 3600 Round 2: With switch: 2021-03-28 03:00:00 3600 :: Without switch: 2021-03-28 03:00:00 3600 Round 3: With switch: 2021-03-28 04:00:00 3600 :: Without switch: 2021-03-28 04:00:00 3600 Actual: Start 2021-03-28 04:00:00 3600 Round 0: With switch: 2021-03-28 03:00:00 3600 :: Without switch: 2021-03-28 04:00:00 3600 Round 1: With switch: 2021-03-28 02:00:00 3600 :: Without switch: 2021-03-28 04:00:00 3600 Round 2: With switch: 2021-03-28 00:00:00 0 :: Without switch: 2021-03-28 04:00:00 3600 Round 3: With switch: 2021-03-27 23:00:00 0 :: Without switch: 2021-03-28 04:00:00 3600 --- Start 2021-03-27 23:00:00 0 Round 0: With switch: 2021-03-28 00:00:00 0 :: Without switch: 2021-03-28 00:00:00 0 Round 1: With switch: 2021-03-28 02:00:00 3600 :: Without switch: 2021-03-28 02:00:00 3600 Round 2: With switch: 2021-03-28 03:00:00 3600 :: Without switch: 2021-03-28 03:00:00 3600 Round 3: With switch: 2021-03-28 04:00:00 3600 :: Without switch: 2021-03-28 04:00:00 3600 ------------------------------------------------------------------------ [2021-06-13 12:04:19] myminibuisness at gmail dot com Great bugs subscribe for detail: https://studyparagraphs.co/paragraph-writing/ ------------------------------------------------------------------------ [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. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=81072 -- Edit this bug report at https://bugs.php.net/bug.php?id=81072&edit=1