Bug #71693 [Opn->Nab]: Date Interval Subtraction for Leap Day

Edit report at https://bugs.php.net/bug.php?id=71693&edit=1 ID: 71693 Updated by: requinix@php.net Reported by: snyderpa at gmail dot com Summary: Date Interval Subtraction for Leap Day -Status: Open +Status: Not a bug Type: Bug Package: Date/time related Operating System: Linux PHP Version: 5.5.32 Block user comment: N Private report: N New Comment: ->add and ->sub *modify* the object. Then they return the instance itself, not a new one. Try code more like $tomorrow = clone $today; $tomorrow->add($oneDayInterval); echo("\nTOMORROW\n"); var_export($tomorrow); Previous Comments: ------------------------------------------------------------------------ [2016-03-01 00:47:24] snyderpa at gmail dot com Also, $tomorrowMinus18 should be in year 1998, not 1980. ------------------------------------------------------------------------ [2016-03-01 00:09:42] snyderpa at gmail dot com Description: ------------ I had a test begin to fail. I was naively expecting subtraction of an interval 'P18Y' to yield a date on which all users born that day would turn 18 years old today. Although the leap day should be an exception for my test case (https://www.quora.com/If-youre-born-on-February-29th-when-do-you-legally-turn-one-year-older) I noticed that there appears to be some brokenness with subtraction of 'P1D' interval from the leap day, and the subsequent subtraction of the 'P18Y' interval from that result. p.s. My Turing test asks for the solution to 50 - 32 -- spooky :-) Test script: --------------- <?php /* get some significant dates */ $today = new DateTime(); echo("\nTODAY\n"); var_export($today); $minorAgeInterval = new DateInterval('P18Y'); $oneDayInterval = new DateInterval('P1D'); $tomorrow = $today->add($oneDayInterval); echo("\nTOMORROW\n"); var_export($tomorrow); $yesterday = $today->sub($oneDayInterval); echo("\nYESTERDAY\n"); var_export($yesterday); $todayMinus18 = $today->sub($minorAgeInterval); echo("\nTODAY MINUS 18\n"); var_export($todayMinus18); $tomorrowMinus18 = $tomorrow->sub($minorAgeInterval); echo("\nTOMORROW MINUS 18\n"); var_export($tomorrowMinus18); $yesterdayMinus18 = $yesterday->sub($minorAgeInterval); echo("\nYESTERDAY MINUS 18\n"); var_export($yesterdayMinus18); ?> Expected result: ---------------- paul@paul-VirtualBox:~$ php php_date_fun.php TODAY DateTime::__set_state(array( 'date' => '2016-02-29 15:49:56', 'timezone_type' => 3, 'timezone' => 'America/Los_Angeles', )) TOMORROW DateTime::__set_state(array( 'date' => '2016-03-01 15:49:56', 'timezone_type' => 3, 'timezone' => 'America/Los_Angeles', )) YESTERDAY DateTime::__set_state(array( 'date' => '2016-02-28 15:49:56', 'timezone_type' => 3, 'timezone' => 'America/Los_Angeles', )) TODAY MINUS 18 DateTime::__set_state(array( 'date' => '1998-03-01 15:49:56', 'timezone_type' => 3, 'timezone' => 'America/Los_Angeles', )) TOMORROW MINUS 18 DateTime::__set_state(array( 'date' => '1980-03-01 15:49:56', 'timezone_type' => 3, 'timezone' => 'America/Los_Angeles', )) YESTERDAY MINUS 18 DateTime::__set_state(array( 'date' => '1998-02-28 15:49:56', 'timezone_type' => 3, 'timezone' => 'America/Los_Angeles', )) Actual result: -------------- paul@paul-VirtualBox:~$ php php_date_fun.php TODAY DateTime::__set_state(array( 'date' => '2016-02-29 15:49:56', 'timezone_type' => 3, 'timezone' => 'America/Los_Angeles', )) TOMORROW DateTime::__set_state(array( 'date' => '2016-03-01 15:49:56', 'timezone_type' => 3, 'timezone' => 'America/Los_Angeles', )) YESTERDAY DateTime::__set_state(array( 'date' => '2016-02-29 15:49:56', 'timezone_type' => 3, 'timezone' => 'America/Los_Angeles', )) TODAY MINUS 18 DateTime::__set_state(array( 'date' => '1998-03-01 15:49:56', 'timezone_type' => 3, 'timezone' => 'America/Los_Angeles', )) TOMORROW MINUS 18 DateTime::__set_state(array( 'date' => '1980-03-01 15:49:56', 'timezone_type' => 3, 'timezone' => 'America/Los_Angeles', )) YESTERDAY MINUS 18 DateTime::__set_state(array( 'date' => '1962-03-01 15:49:56', 'timezone_type' => 3, 'timezone' => 'America/Los_Angeles', )) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=71693&edit=1