Bug #76983 [Com]: date('i') returns wrong value for Dublin timezone

Edit report at https://bugs.php.net/bug.php?id=76983&edit=1 ID: 76983 Comment by: tomas at matrixinternet dot ie Reported by: tomas at matrixinternet dot ie Summary: date('i') returns wrong value for Dublin timezone Status: Feedback Type: Bug Package: Date/time related Operating System: Ubuntu 16.04 PHP Version: 5.6.38 Block user comment: N Private report: N New Comment: Yes, tzdata version on the affected system is 2018e. Previous Comments: ------------------------------------------------------------------------ [2018-10-08 06:52:56] requinix@php.net It looks like tzdata had issues with the way it stored DST information for Europe/Dublin. What version of tzdata do you have installed? Is it at least 2018e? ------------------------------------------------------------------------ [2018-10-08 06:38:55] tomas at matrixinternet dot ie Description: ------------ We use date('I') (capital i) to detect daylight saving time being in action or not. It kept returning "1" quite happily throughout the summer. On 29/09/2018 around 7:00 am, it started returning "0", indicating a change to a winter time. This happened pretty much exactly one full month before the change was about to happen on October 29. Linux Timezone is: Europe/Dublin (IST, +0100) PHP timezone is set via date_default_timezone_set('Europe/Dublin'); date('I', strtotime('2018-09-29 02:00:00')) // returns "0" - which is wrong as DST is active now! date('I', strtotime('2018-11-29 02:00:00')) // returns "1" - which is wrong as DST is Summer time! This issue seems to happen specifically on Amazon AWS EC2 instances. A newly installed server instance returns the correct value for around a day, but then it seems to switch over. We weren't able to replicate this issue on a non-AWS instance. Test script: --------------- date_default_timezone_set('Europe/London'); if (date('I', strtotime('2018-09-29 02:00:00'))) { echo 'We are in DST!'; } else { echo 'We are not in DST!'; } date_default_timezone_set('Europe/Dublin'); if (date('I', strtotime('2018-09-29 02:00:00'))) { echo 'We are in DST!'; } else { echo 'We are not in DST!'; } date_default_timezone_set('Europe/Paris'); if (date('I', strtotime('2018-09-29 02:00:00'))) { echo 'We are in DST!'; } else { echo 'We are not in DST!'; } Expected result: ---------------- We are in DST! We are in DST! We are in DST! Actual result: -------------- We are in DST! We are not in DST! We are in DST! ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=76983&edit=1