Bug #74249 [Opn->Dup]: Instance created using "first day of ..." locks the day

Edit report at https://bugs.php.net/bug.php?id=74249&edit=1 ID: 74249 Updated by: peehaa@php.net Reported by: peehaa@php.net Summary: Instance created using "first day of ..." locks the day -Status: Open +Status: Duplicate Type: Bug Package: Date/time related PHP Version: Irrelevant Block user comment: N Private report: N New Comment: CLosing as dupe of https://bugs.php.net/bug.php?id=63863 Previous Comments: ------------------------------------------------------------------------ [2017-03-15 10:00:03] requinix@php.net Note I reopened bug #63863 earlier for this same issue. ------------------------------------------------------------------------ [2017-03-15 09:35:40] peehaa@php.net Description: ------------ After initializing a new DateTime object using "first day of this ..." DateTime::setDate() doesn't correctly set the day anymore. It will always result 1. $date1 = new \DateTime('first day of this month'); echo $date1->format('Y-m-d') . "\n"; // correct: 2017-03-01 $date1->setDate(2017, 1, 8); echo $date1->format('Y-m-d') . "\n"; // wrong: 2017-01-01 I tried several things like "first day of january" and "first day of this month". https://3v4l.org/I2maQ Test script: --------------- <?php $date1 = new \DateTime('first day of this month'); echo $date1->format('Y-m-d') . "\n"; $date1->setDate(2016, 1, 8); echo $date1->format('Y-m-d') . "\n"; $date2 = new \DateTime('first day of january'); echo $date2->format('Y-m-d') . "\n"; $date2->setDate(2016, 3, 8); echo $date2->format('Y-m-d') . "\n"; Expected result: ---------------- 2017-03-01 2016-01-08 2017-01-01 2016-03-08 Actual result: -------------- 2017-03-01 2016-01-01 2017-01-01 2016-03-01 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=74249&edit=1