Handling of conflicting time zones in the DateTime / DateTimeImmutable constructor

[kixe]

Description

The following code:

<?php

// given: a time string including timezone (Zulu)
$zuluTimeString = '2024-11-07T11:00:00Z';

$dt = new DateTime($zuluTimeString, new DateTimeZone('Europe/Berlin'));
var_dump($dt->getTimeZone()->getName());
var_dump($dt->format('Y-m-d H:i:sp'));

$dt = new DateTime($zuluTimeString);
$dt->setTimezone(new DateTimeZone('Europe/Berlin'));
var_dump($dt->getTimeZone()->getName());
var_dump($dt->format('Y-m-d H:i:sp'));

$dt = new DateTimeImmutable($zuluTimeString, new DateTimeZone('Europe/Berlin'));
var_dump($dt->getTimeZone()->getName());
var_dump($dt->format('Y-m-d H:i:sp'));

$dt = new DateTimeImmutable($zuluTimeString);
$dt->setTimezone(new DateTimeZone('Europe/Berlin'));
var_dump($dt->getTimeZone()->getName());
var_dump($dt->format('Y-m-d H:i:sp'));

?>

Resulted in this output:

string(1) "Z"
string(20) "2024-11-07 11:00:00Z"
string(13) "Europe/Berlin"
string(25) "2024-11-07 12:00:00+01:00"
string(1) "Z"
string(20) "2024-11-07 11:00:00Z"
string(1) "Z"
string(20) "2024-11-07 11:00:00Z"

But I expected this output instead:

either (always)
string(13) "Europe/Berlin"
string(25) "2024-11-07 12:00:00+01:00"
or Error / Warning due to Timezone conflict in parameters 

PHP Version

PHP 8.3.10

Operating System

MacOS 12.7.4

[heiglandreas]

This is expected behaviour.

As the $zuluTimeString contains a timezone, the second parameter is ignored.

Check the Note in https://www.php.net/manual/en/datetimeimmutable.construct.php

The $timezone parameter and the current timezone are ignored when the $datetime parameter either is a UNIX timestamp (e.g. @946684800) or specifies a timezone (e.g. 2010-01-28T15:00:00+02:00, or 2010-07-05T06:00:00Z).

[kixe]

@heiglandreas
Fine. But what about the different results in DateTime and DateTimeImmutable if the timezone is changed later via setTimezone() ?

[kixe]

... got it

<?php
$dt = new \DateTimeImmutable($zuluTimeString);
$dt = $dt->setTimezone(new \DateTimeZone('Europe/Berlin'));
var_dump($dt->getTimeZone()->getName());
var_dump($dt->format('Y-m-d H:i:sp'));
?>

result

string(13) "Europe/Berlin"
string(25) "2024-11-07 12:00:00+01:00"