[php-src] Issue #13267: DateTime setISODate() results in wrong timestamp?

Issue: https://github.com/php/php-src/issues/13267 Author: Daijobou ### Description I call every Monday a cronjob at 00:01. I want known the year and week from last week. ```php <?php $dt = new DateTime('last week monday 00:00:01', new DateTimeZone('Europe/Berlin')); $year = (int)$dt->format('Y'); $week = (int)$dt->format('W'); // After this, I call a second script with parameters ($year and $week) few times for different tasks $dto = new DateTime(); $dto->setISODate($year, $week); $fmt = new IntlDateFormatter('de_DE', IntlDateFormatter::NONE, IntlDateFormatter::NONE, 'Europe/Berlin'); $fmt->setPattern('LLL dd'); // Hint: $dto->getTimestamp() is the date a week ago, but with current time. So its always the time its called. $week_start = $fmt->format($dto->getTimestamp()); $dto->modify('+6 days'); // for sunday $week_end = $fmt->format($dto->getTimestamp()); echo $week_start . ' - ' . $week_end; ``` Resulted in this output: ``` Jan 23 - Jan 29 ``` But I expected this output instead, for Timezone 'Europe/Berlin': ``` Jan 22 - Jan 28 ``` The parameters $year and $week are only determined once. With these two values, the same script is called several times to create each time a graphic containing the date for the Monday and Sunday of the previous week. The script is called by a cronjob 00:01 every Monday. The graphics were created on the server at 00:01:23 and later. The script needs less than 1 second to create the graphics. So I remove the images and call the script again ~9 o'clock and its shows me now the correct values "Jan 22 - Jan 28". Is this a bug or am I doing something wrong here? Because its worked for many years, but since 2024 its startet with wrong dates (one date shifted). 03.01. wrong date for last week December. 08.01. again wrong date **15.01. shows the correct date 22.01. shows the correct date** 29.01. again wrong date So its strange. ### PHP Version PHP 8.2.15 ### Operating System AlmaLinux 8.9