DateTime::diff doesnt evaluate daylight saving time correctly

[chaosben]

Description

The following code:

<?php

$dt1 = new DateTime('2022-08-01 07:00:00', new DateTimeZone('Europe/Berlin'));
$dt2 = new DateTime('2022-08-01 07:00:00 +02:00');

echo "DT1: {$dt1->format('c')}" . PHP_EOL;
echo "DT2: {$dt2->format('c')}" . PHP_EOL;

$diff = $dt1->diff($dt2);

echo "Diff: {$diff->format('%h')}";

Resulted in this output:

DT1: 2022-08-01T07:00:00+02:00
DT2: 2022-08-01T07:00:00+02:00
Diff: 1

But I expected this output instead:

DT1: 2022-08-01T07:00:00+02:00
DT2: 2022-08-01T07:00:00+02:00
Diff: 0

According to https://3v4l.org/eOUP5 this bug exists since PHP 8.1.0

PHP Version

PHP 8.1.9

Operating System

Fedora 36

[cmb69]

Indeed, that looks wrong to me.

[hormus]

@cmb69 @derickr forgot to add a note in the manual for diff, if they are with timezone type int 3 the result is effective otherwise if different timezones will be converted to UTC and calculate the difference. if you need I will send you when diff has been modified.

yes it's a bug for me too

Valid period transitions:

<?php

date_default_timezone_set('Europe/Berlin');
$origin = new DateTime('2022-03-27 02:00:00', new DateTimeZone('Europe/Berlin'));
$target = new DateTime('2022-03-27 02:00:00 +0200');
$origin->setTimeZone(new DateTimeZone('Europe/Berlin'));
$origin = new DateTime($origin->format('Y-m-d H:i:s'), new DateTimeZone('Europe/Berlin'));

$simil_utc = $target->format('Y-m-d H:i:s');
$target = new DateTime($simil_utc, new DateTimeZone('Europe/Berlin'));
$target->setTimeZone(new DateTimeZone('Europe/Berlin'));
$target = new DateTime($target->format('Y-m-d H:i:s'), new DateTimeZone('Europe/Berlin'));
$interval = $origin->diff($target);

echo $interval->format('%R%a days %h hours') . "\n";
var_dump($origin, $target);

?>

DateTime::Diff php 8.10 > if object same type offset timezone $origin and $target is local time object. Means for DST +0200: Europe/Berlin = Europe/Berlin or Europe/Berlin = +0200 or Europe/Berlin = CEST (ex. Localtime object 2022-03-27 02:00:00 - 2022-03-27 02:00:00 = 0 or 2022-03-27 03:00:00 - 2022-03-27 03:00:00 = 0 or Europe/Berlin = +0200 2022-03-27 03:00:00 - 2022-03-27 02:00:00 = 0), for Europe/Berlin: ST (+0100) and DST (+0200) 2022-03-27 01:00:00 - 2022-03-27 03:00:00 = 1 or 2022-03-27 01:00:00 - 2022-03-27 02:00:00 = 1
Note* for ST type 3 and DST type 1: besides the bug mentioned Diff does not support several transitions. In all other cases it converts it to UTC.
DateTime::Diff php 5.3.0 < php 8.1.0 $origin and $target is UTC object. Europe/Berlin to UTC. Means: (ex. UTC object 2022-03-27 01:00:00 - 2022-03-27 01:00:00 = 0)

[derickr]

This seems to be already fixed in the 8.1.10RC1. I can successfully recreate this with 8.1.9, but not with 8.1.10RC1. I believe it is a duplicate of #8730.

[chaosben]

🥳 Thanks!