[Tickets #13947] Re: Calendar breaks on DST start date

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Ticket URL: https://bugs.horde.org/ticket/13947
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  Ticket             | 13947
  Updated By         | tiago.delboni at almg.gov.br
  Summary            | Calendar breaks on DST start date
  Queue              | Kronolith
  Version            | 4.2.2
  Type               | Bug
  State              | Assigned
  Priority           | 1. Low
  Milestone          |
  Patch              |
  Owners             | Horde Developers
+New Attachment     | dstbug.jpg
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tiago.delboni at almg.gov.br (2016-10-14 13:23) wrote:

We're also observing this behaviour in Firefox 45.4.0 with Brazilian  
DST. For 2016 the duplicated day in the calendar is 15th of October.

Any patch to this would be utterly appreciated!

IMHO this should not be a low priority bug. It messes up people  
calendars for an entire month, shifting days in such way that people  
would easily miss an important meet or task.

> Calendar views broken on DST start date (see attached).
>
> To reproduce:
> 1 - set the timezone (php.ini) to one that has DST starting at 00:00  
> of a known date. For example, date.timezone = "America/Sao_Paulo".
> 2 - access the year or month view of the calendar on the month that  
> DTS starts (in this case, October) and look at the DST start date
>
> Interestingly, Android is plagued by almost the exact same bug:
> https://code.google.com/p/android/issues/detail?id=74754
>
> This is caused by using datetime variables with the time unset (thus  
> 00:00). There is no 00:00 on the DST start date (the clock "jumps"  
> from 23:59 to 01:00), so functions using that date return bad  
> results which are not handled properly.
>




tiago.delboni at almg.gov.br (2016-10-14 13:23) uploaded: dstbug.jpg

https://bugs.horde.org/horde/services/download/?app=whups&actionID=download_file&file=dstbug.jpg&ticket=13947&fn=%2Fdstbug.jpg