IntlDateFormater: recalculation of date gregorian>chinese(!)>gregorian fails

[porthd]

Description

Other calendars like islamic, buddhist instead of chinese are working like expected. The following code fails (discussed in german language here ):

<?php
$locale = 'de_DE@calendar=chinese';

$traditionalFormatter = new IntlDateFormatter(
        $locale,
    IntlDateFormatter::MEDIUM,
    IntlDateFormatter::SHORT,
    'Europe/Berlin',
    IntlDateFormatter::TRADITIONAL
);

$gregorianFormatter = new IntlDateFormatter(
        $locale,
    IntlDateFormatter::MEDIUM,
    IntlDateFormatter::SHORT,
    'Europe/Berlin',
    IntlDateFormatter::GREGORIAN
);

$dateTime = DateTime::createFromFormat('Y-m-d H:i:s', '2022-10-30 23:27:06');

$traditionalDate = $traditionalFormatter->format($dateTime);
$parsedTimestamp = $traditionalFormatter->parse($traditionalDate);

var_dump($gregorianFormatter->format($dateTime));
var_dump($gregorianFormatter->format($parsedTimestamp));

Resulted in this output:

string(18) "2022 Okt. 31 00:27"
string(17) "2599 Dez. 5 00:27"

But I expected this output instead:

string(18) "2022 Okt. 31 00:27"
string(17) "2022 Okt. 31 00:27"

PHP Version

PHP 7.4.33, PHP 8.0.27, PHP 8.1.14, PHP 8.2.1

Operating System

No response

[LamentXU123]

IMO This is not a PHP bug. The default Chinese calendar pattern contains a cyclic year (U) but does not contain the cycle/era. So, dates in different 60-year cycles can produce exactly the same formatted string, so the original timestamp cannot be recovered unambiguously.

IntlDateFormatter::parseToCalendar() can be used when the current cycle should be assumed. I am therefore closing.