note 106058 added to datetime.add

I'm not sure, but there is strange behaviour when add 30D to 2369-12-01 (and for 2369+400, 2369+800, 2369+1200 ... year) <?php $sep31 = new DateTime('2369-12-31'); echo '2369-12-31: ', $sep31->format('Y-m-d H:i:s'), PHP_EOL; assert($sep31->format('Y-m-d H:i:s') === '2369-12-31 00:00:00'); $date = new DateTime('2369-12-01'); $date->add(new DateInterval('P30D')); echo '2369-12-01 + P30D = 2369-01-31 00:00:00 ? => ', $date->format('Y-m-d H:i:s'), ' - wtf?', PHP_EOL; assert($date->format('Y-m-d H:i:s') === '2369-01-31 00:00:00'); // false ---- Server IP: 93.93.89.9 Probable Submitter: 80.243.13.243 ---- Manual Page -- http://www.php.net/manual/en/datetime.add.php Edit -- https://master.php.net/note/edit/106058 Del: integrated -- https://master.php.net/note/delete/106058/integrated Del: useless -- https://master.php.net/note/delete/106058/useless Del: bad code -- https://master.php.net/note/delete/106058/bad+code Del: spam -- https://master.php.net/note/delete/106058/spam Del: non-english -- https://master.php.net/note/delete/106058/non-english Del: in docs -- https://master.php.net/note/delete/106058/in+docs Del: other reasons-- https://master.php.net/note/delete/106058 Reject -- https://master.php.net/note/reject/106058 Search -- https://master.php.net/manage/user-notes.php