On Mon, Mar 06, 2017 at 12:44:53PM +0200, JS wrote:
> Hi!
> 
> For some reason DST change in southern hemisphere occurs 1 hour late
> when clock is turned backward and 1 hour early when clock is turned
> forward.
> 
> For example, timezone for spec for Brazil is:
> BRT3BRST,M10.3.0/0,M2.3.0/0
> Which means that DST change occurs at midnight.
> 
> Output of date for both DST changes:
> 
> ~# date
> Sun Feb 19 00:59:59 BRST 2017
> ~# date
> Sun Feb 19 00:00:00 BRT 2017
> 
> ~# date
> Sat Oct 14 22:59:59 BRT 2017
> ~# date
> Sun Oct 15 00:00:00 BRST 2017
> 
> I've tested the same code on same hardware but with uClibc library
> instead of musl and it works fine.

I think this is indeed a bug. Can you confirm that the correct
progressions across DST change should be:

Sat Feb 18 23:59:59 BRST 2017
Sat Feb 18 23:00:00 BRT 2017

Sat Oct 14 23:59:59 BRT 2017
Sun Oct 15 01:00:00 BRST 2017

If so I think I have a working fix (see attached). The logic for
handling DST transition times for southern hemisphere was trying to do
something special that was actually wrong and didn't need to be
special-cased.

Rich