Bug #78691 [NEW]: DateTime ->modify incorrect behavior in some time zones

From: writejohnemail at gmail dot com Operating system: Linux PHP version: 7.4.0RC4 Package: Date/time related Bug Type: Bug Bug description:DateTime ->modify incorrect behavior in some time zones Description: ------------ In time zones that make a daylight savings change at midnight, on the day of the daylight savings change, ->modify('-1 second') does not work as expected. America/Santiago, America/Havana, Asia/Tehran, America/Asuncion are a few of the time zones that have this behavior Test script: --------------- $timezone = 'America/Santiago'; $dateString = "2020-09-06"; $dt = new \DateTime($dateString); $dtz = new \DateTimeZone($timezone); $dt->setTimezone($dtz); echo 'the start of the day:<br>'; $dt->modify('today'); echo $dt->getTimestamp(); echo '<br><br>the start of the day, minus one second. this is incorrect:<br>'; $dt->modify('-1 second'); echo $dt->getTimestamp(); Expected result: ---------------- 1599364799 Actual result: -------------- 1599368399 -- Edit bug report at https://bugs.php.net/bug.php?id=78691&edit=1 -- Fix committed: https://bugs.php.net/fix.php?id=78691&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=78691&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=78691&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=78691&r=needscript Try newer version: https://bugs.php.net/fix.php?id=78691&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=78691&r=support Expected behavior: https://bugs.php.net/fix.php?id=78691&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=78691&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=78691&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=78691&r=globals PHP version support discontinued: https://bugs.php.net/fix.php?id=78691&r=phptooold Daylight Savings: https://bugs.php.net/fix.php?id=78691&r=dst IIS Stability: https://bugs.php.net/fix.php?id=78691&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=78691&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=78691&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=78691&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=78691&r=mysqlcfg