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

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:

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

Inizia riproducendo l’esempio di IntlDateFormatter per Europe/Amsterdam e confronta le versioni di ICU elencate nell’issue, usando i Dockerfile Debian e latest-ICU referenziati. Verifica se l’offset storico errato proviene da PHP o da ICU; il lavoro è completato quando il formatter restituisce il risultato atteso 1940 UTC+00:20 oppure l’issue è documentata come una limitazione upstream di ICU.