iCal event bug confirmed

Yesterday we covered a report of an event bug in iCal where -- in the time zone for Brazil, GMT -03 -- scheduling an event on the second weekend of October (9-10, 2004; 8-9, 2005; etc.) results in the event being "invisible" in week view and badly truncated in month view, if you can even create the event at all.

We've since received several confirmations of this bug, all in GMT -03 or GMT -04 time zones. For example, Rodrigo Valenzuela writes:

"I was able to reproduce the iCal problem reported by your reader Cassio Gondim. I tried to enter an event on October 9 (saturday) and iCal allowed it, but then it did not show when I switched to Week view. (OS X 10.3.4 with all available patches installed. I am currently located in Chile, which is GMT -04.)"

Reader David Empson provides a theory as to the cause of this problem:

"It appears to be related to the date on which daylight saving begins, which is October 9th 2004 for eastern Brazil. I didn't observe a similar issue for my own daylight saving start date (October 3rd in New Zealand).

"Mac OS X stores all the time zone transition tables in the directory /usr/share/zoneinfo. They are sorted into subdirectories by country and sub-zone or city within the country...Here are the entries for 2004:

Brazil/East Sun Feb 15 01:59:59 2004 GMT = Sat Feb 14 23:59:59 2004 BRST isdst=1
Brazil/East Sun Feb 15 02:00:00 2004 GMT = Sat Feb 14 23:00:00 2004 BRT isdst=0
Brazil/East Sun Oct 10 02:59:59 2004 GMT = Sat Oct 9 23:59:59 2004 BRT isdst=0
Brazil/East Sun Oct 10 03:00:00 2004 GMT = Sun Oct 10 01:00:00 2004 BRST isdst=1

"The only 'unusual' factor I can see here is that Brazil's daylight saving transition occurs at local midnight -- i.e., as soon as the time rolls over from 02:59:59 GMT (23:59:59 on October 9th in Brazil standard time) to 03:00:00 GMT, the local time jumps to 01:00:00 on October 10th in Brazil summer time.

"I expect that iCal has a bug in its handling of time zones when the daylight saving transition occurs at midnight, i.e. coinciding with a date change. This would also affect any other country with similar rules, but I haven't gone searching for any to confirm this. The US (and New Zealand) daylight saving transition is 2 to 3 a.m., and the date doesn't change, so this bug doesn't appear."

Can you replicate this bug in your time zone? Drop us an email at Late-breakers@macfixit.com.

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