There's a not un-serious push to switch to permanent daylight savings in Cascadia (western part of north america). I wonder what this will do to all the date code that doesn't use a library or libraries that aren't updated.
DST rules change all the time, all over the world. Any software that gets DST right today must be using a library. Even if you only look at the US, ten years ago Congress changed the dates that DST starts and ends and it wasn't a big deal. There's also many places in the US today that use permanent DST or permanent non-DST, so that's not even new, really.
Heh. Hence my comment. I actually had to deal with that DST change on a bunch of embedded systems back in 2006 (or so). Super fun pushing updates to 100+ systems over analog modems.
Dates are hard. Use a library. Always.