Bug #72470 [NEW]: modify() doesn't take into account DST changes

From: matthieux dot dekamen at gmail dot com Operating system: PHP version: 7.1.0alpha1 Package: Date/time related Bug Type: Bug Bug description:modify() doesn't take into account DST changes Description: ------------ modify() doesn't take into account DST changes. For example, if I add 23 hours with DateInterval where a DST change occurs: echo date_default_timezone_get(); // prints Europe/Amsterdam $dateTime = new DateTime('2016-10-29 10:00:00'); $dateTime->add(new DateInterval('PT23H')); I get the expected result: 2016-10-30T08:00:00+01:00 (clock went backwards for 1 hour) But if I add 23 hours with the modify() function on the same date: $dateTime = new DateTime('2016-10-29 10:00:00'); $dateTime->modify('+ 23 hours'); I get: 2016-10-30T09:00:00+01:00 As you see the result here is different. modify() seems to not take into account DST changes. https://3v4l.org/4fncr -- Edit bug report at https://bugs.php.net/bug.php?id=72470&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=72470&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=72470&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=72470&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=72470&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=72470&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=72470&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=72470&r=needscript Try newer version: https://bugs.php.net/fix.php?id=72470&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=72470&r=support Expected behavior: https://bugs.php.net/fix.php?id=72470&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=72470&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=72470&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=72470&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=72470&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=72470&r=dst IIS Stability: https://bugs.php.net/fix.php?id=72470&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=72470&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=72470&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=72470&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=72470&r=mysqlcfg