Edit report at https://bugs.php.net/bug.php?id=81072&edit=1
ID: 81072
Comment by: r dot aalderink at visymo dot com
Reported by: ph-bugs at allenjb dot me dot uk
Summary: Incorrect behavior of DateTime->modify across DST
changes
Status: Verified
Type: Bug
Package: Date/time related
PHP Version: 8.0.6
Block user comment: N
Private report: N
New Comment:
Ran into the same issue, I have a very simple oneliner to reproduce it:
-----
echo (new \DateTime('2022-03-13 03:00:00', new
\DateTimeZone('America/Los_Angeles')))->modify('-5
minutes')->format('Y-m-d H:i:s');
-----
This becomes: 2022-03-13 03:55:00
Expected: 2022-03-13 01:55:00
Previous Comments:
------------------------------------------------------------------------
[2021-10-01 18:25:40] cmb@php.net
> 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
So this about <https://3v4l.org/XWdf2>, right?
If so, yes, that doesn't look right.
------------------------------------------------------------------------
[2021-07-30 10:53:24] antonino dot spampinato86 at gmail dot com
Sorry change $dtWithout_test1 = incrementWithoutSwitch($dtWithout, $invert); to $dtWithout =
incrementWithoutSwitch($dtWithout, $invert);
The bug is there, the expected result is not obtained. :-)
------------------------------------------------------------------------
[2021-07-30 10:43:46] antonino dot spampinato86 at gmail dot com
This is the refined version proposed. DST transition bug for modify function exists. Bug 74224
mentions that from php 8.1 that diff function has been changed and supports time not conversion to
UTC and this makes time or date calculations consistent with local time. Actually diff function also
suffers from DST or ST problems, If you deem it necessary I will also show it to you.
function incrementWithSwitch($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
------------------------------------------------------------------------
[2021-05-30 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);
}
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