php / php/php-src

`IntlDateFormatter` returns wrong output for 1940 date in Amsterdam timezone

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Bug Extension: intl Status: Needs Triage
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Description

Description

The following code:

<?php

$timezone = new DateTimeZone("Europe/Amsterdam");
$date = new DateTime("1940-01-01 00:00:00", $timezone);
var_dump($date);

$formatter = new IntlDateFormatter("en-US");
var_dump($formatter->format($date));

Resulted in this output:

object(DateTime)#2 (3) {
  ["date"]=>
  string(26) "1940-01-01 00:00:00.000000"
  ["timezone_type"]=>
  int(3)
  ["timezone"]=>
  string(16) "Europe/Amsterdam"
}
string(69) "Sunday, December 31, 1939 at 11:40:00 PM Coordinated Universal Time"

But I expected this output instead:

object(DateTime)#2 (3) {
  ["date"]=>
  string(26) "1940-01-01 00:00:00.000000"
  ["timezone_type"]=>
  int(3)
  ["timezone"]=>
  string(16) "Europe/Amsterdam"
}
string(48) "Monday, January 1, 1940 at 12:00:00 AM GMT+00:20"

Additional details

Until 16 May 1940, The Netherlands used UTC+00:20 as timezone. It looks like IntlDateFormatter is not aware of the UTC+00:20 timezone, so it outputs the date in UTC.

The occurrence of the problem seems related to the version of the ICU library:

Environment Source PHP version ICU version Output
3v4l.org https://3v4l.org/UoVSs 8.2.4 57.1 ✅ As expected
Docker + Debian libicu Dockerfile 8.2.4 67.1 ❌ Wrong
Docker + latest libicu Dockerfile 8.2.4 72.1 ❌ Wrong

I am not familiar enough with the ICU library to assess whether the problem originates there. Since the wrong output is present in PHP when using the latest versions (of PHP and the ICU library), I am submitting the bug here.

PHP Version

8.2.4

Operating System

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the IntlDateFormatter example for Europe/Amsterdam and compare the ICU versions listed in the issue, using the referenced Debian and latest-ICU Dockerfiles. Trace whether the incorrect historical offset comes from PHP or ICU; done means the formatter returns the expected 1940 UTC+00:20 result or the issue is documented as an upstream ICU limitation.

Written by the indexing model from the issue text.

Assessment

Tech stack
php
Domain
internationalization
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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