DateRule setting time to 00:00:00 results in off-by-one errors

[graste]

This behaviour breaks expectations when one is not thinking about this. Example:

System is using UTC. PHP script sets default timezone to CET (+01:00). ValueHolder sets value as follows:

date_default_timezone_set('Europe/Berlin');
$value = $date_attribute->createValueHolder();
$value->setValue('2016-12-10');

This input is treated as follows in DateRule:

• create DateTimeImmutable as 2016-12-10T00:00:00.000000+01:00
• force internal timezone to UTC: 2016-12-09T23:00:00.000000+00:00
• recreate as 2016-12-09T23:00:00.000000+00:00
• set time to 00:00:00 resulting in 2016-12-09T00:00:00.000000+00:00

This means we now have a date set internally that is off by one. 🎱

Suggested solution: don't set the time info at all or make it optional.