Bug #76686 [NEW]: Datetime->sub calculates incorrectly on dates late in a month

From: janne at consilia dot fi Operating system: PHP version: 7.0.31 Package: Date/time related Bug Type: Bug Bug description:Datetime->sub calculates incorrectly on dates late in a month Description: ------------ The PHP version is actually 7.0.30 (not in the list) The test script produces the following result: 2018-07-31 2018-07-01 2018-06-01 Test script: --------------- <?php $now = new DateTime('2018-07-31'); echo $now->format('Y-m-d') . "\n"; echo $now->sub(new DateInterval('P1M'))->format('Y-m-d') . "\n"; echo $now->sub(new DateInterval('P1M'))->format('Y-m-d') . "\n"; -- Edit bug report at https://bugs.php.net/bug.php?id=76686&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=76686&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=76686&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=76686&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=76686&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=76686&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=76686&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=76686&r=needscript Try newer version: https://bugs.php.net/fix.php?id=76686&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=76686&r=support Expected behavior: https://bugs.php.net/fix.php?id=76686&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=76686&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=76686&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=76686&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=76686&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=76686&r=dst IIS Stability: https://bugs.php.net/fix.php?id=76686&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=76686&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=76686&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=76686&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=76686&r=mysqlcfg