id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
6045,Date/Time: dst_calculator::local_is_dst doesn't deal with DST changeover at end of day,Matt Adam <matt.adam@…>,az_sw_dude,"Hello boosters,

dst_calculator::local_is_dst assumes that the hour lost in the ""forward"" DST changeover (in Spring, when DST begins) fully occurs within a single day.  If your time zone rule specifies that DST begins at 23:59:99.999 on October 15th, with a duration of an hour, and you attempt to create a ptime for 00:00:00.000 on October 16th, it will succeed even though it ought to return invalid_time_label.

I admit that this seems like an odd case, and personally I would expect all DST offsets to be in the 0h-3h range.  However if you are creating custom time zones based on the win32 time zone information, the GetTimeZoneInformation API returns a TIME_ZONE_INFORMATION struct with values returned a millisecond before midnight.  Specifically this happens with Brasilian standard/daylight time.

For now I am ""cleaning up"" these odd values returned from windows, but boost probably should do this calculation correctly to begin with.

I can provide a repro case if need be, although I think the behaviour of the code in question is pretty clear.

Thanks,

Matt Adam",Bugs,new,To Be Determined,date_time,Boost 1.47.0,Problem,,,