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

From: tomas at matrixinternet dot ie Operating system: Ubuntu 16.04 PHP version: 5.6.38 Package: Date/time related Bug Type: Bug Bug description:date('i') returns wrong value for Dublin timezone 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 bug report at https://bugs.php.net/bug.php?id=76983&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=76983&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=76983&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=76983&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=76983&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=76983&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=76983&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=76983&r=needscript Try newer version: https://bugs.php.net/fix.php?id=76983&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=76983&r=support Expected behavior: https://bugs.php.net/fix.php?id=76983&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=76983&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=76983&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=76983&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=76983&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=76983&r=dst IIS Stability: https://bugs.php.net/fix.php?id=76983&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=76983&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=76983&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=76983&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=76983&r=mysqlcfg