Bug #79452 [NEW]: DateTime::diff() generates months differently between time zones

From: corey dot taylor dot fl at gmail dot com Operating system: PHP version: 7.4.4 Package: Date/time related Bug Type: Bug Bug description:DateTime::diff() generates months differently between time zones Description: ------------ If you create DateTime instances in 'America/New_York' or 'UTC' time zone and compare them using DateTime::diff() the months value is different than using DateTime instances in 'Europe/Berlin' or 'Asia/Tokyo'. date_default_timezone_set('America/New_York'); $from = new DateTime('2019-06-01'); $to = new DateTime('2019-10-01'); var_dump($from->diff($to)->m); -- int(4) date_default_timezone_set('Asia/Tokyo'); $from = new DateTime('2019-06-01'); $to = new DateTime('2019-10-01'); var_dump($from->diff($to)->m); -- int(3) The generated days value is the same for both. If this isn't determined to be an implementation error, then can the exepcation be documented for DateTime::diff()? Right now, it's impossible to tell how the DateTime objects are compared between time zones. Expected result: ---------------- The generated difference in months is the same for 2 dates is the same regardless of the time zone they are in. -- Edit bug report at https://bugs.php.net/bug.php?id=79452&edit=1 -- Fix committed: https://bugs.php.net/fix.php?id=79452&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=79452&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=79452&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=79452&r=needscript Try newer version: https://bugs.php.net/fix.php?id=79452&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=79452&r=support Expected behavior: https://bugs.php.net/fix.php?id=79452&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=79452&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=79452&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=79452&r=globals PHP version support discontinued: https://bugs.php.net/fix.php?id=79452&r=phptooold Daylight Savings: https://bugs.php.net/fix.php?id=79452&r=dst IIS Stability: https://bugs.php.net/fix.php?id=79452&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=79452&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=79452&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=79452&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=79452&r=mysqlcfg