Date::diffInMonths returns unexpected result in Asia/Tokyo about chronos

[othercorey]

From the php ticket, diff() converts the DateTime objects to UTC before comparing.

This means any time zone change that causes a date change can affect the month calculation. Waiting to see if there is more discussion, but the only solution might be to "fake" the date in UTC before calling diff() to get a consistent result.

[chinpei215]

No. DST is not adopted in Japan. In addition, it happens even in winter season. For example:

date_default_timezone_set('Asia/Tokyo');

$from = new DateTime('2019-11-01');
$to = new DateTime('2019-12-01');

var_dump($from->diff($to)->m);
// int(0)

It seems like the timezone offset (+09:00 in Japan) is ignored in the diff method.

date_default_timezone_set('Asia/Tokyo');

$from = new DateTime('2019-11-01 09:00');
$to = new DateTime('2019-12-01 09:00');

var_dump($from->diff($to)->m);
// int(1)

[othercorey]

I submitted a bug report. Hopefully, we get an answer on how diff() is calculated for different time zones.

https://bugs.php.net/bug.php?id=79452

[markstory]

Does this time range cross the DST boundary for Tokyo? If so you might be an hour short of four months.

[othercorey]

Fixed in #283