Bug #81072 [Com]: Incorrect behavior of DateTime->modify across DST changes
| From: | php-bugs at allenjb dot me dot uk | Date: | Sun, 23 May 2021 09:45:58 +0000 |
| Subject: | Bug #81072 [Com]: Incorrect behavior of DateTime->modify across DST changes | ||
| References: | 1 | Groups: | php.bugs |
| Request: | Send a blank email to php-bugs+get-233994@lists.php.net to get a copy of this message | ||
Edit report at https://bugs.php.net/bug.php?id=81072&edit=1
ID: 81072
Comment by: php-bugs at allenjb dot me dot uk
Reported by: ph-bugs at allenjb dot me dot uk
Summary: Incorrect behavior of DateTime->modify across DST
changes
Status: Feedback
Type: Bug
Package: Date/time related
PHP Version: 8.0.6
Block user comment: N
Private report: N
New Comment:
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: ". $dtWithout->format(\DateTime::RFC3339);
}
Previous Comments:
------------------------------------------------------------------------
[2021-05-22 20:17:54] requinix@php.net
Looks like 3v4l.org is behind a few versions - maybe was impacted by the GitHub move.
I can't reproduce locally. Can you test in current master (8.1)? If it works there then this
may be a duplicate of 74274.
------------------------------------------------------------------------
[2021-05-22 18:55:52] ph-bugs at allenjb dot me dot uk
Description:
------------
See https://3v4l.org/hGXcr
Working on a fix for https://github.com/dragonmantank/cron-expression/issues/111
As you can see, when working backwards with ->modify("-1 hour") DateTime fails to
properly handle the DST change and keeps pushing the time forward to 03:00:00
Working forwards with ->modify("+1 hour") does not exhibit the same behavior.
(The code examples also show a workaround, which involved switching timezones while performing the
->modify)
Test script:
---------------
<?php
function incrementWithSwitch($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
------------------------------------------------------------------------
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Edit this bug report at https://bugs.php.net/bug.php?id=81072&edit=1