On Mon, 3 Mar 2025 at 21:35, Jonathan Wakely <jwak...@redhat.com> wrote:
>
> On Mon, 3 Mar 2025 at 21:24, Matt Johnson-Pint via tz <tz@iana.org> wrote:
> >
> > Yes. Australia/Lord_Howe currently has a 30-minute difference between its
> > standard and daylight times. Also, Antarctica/Troll has a 2-hour
> > difference.
> >
> > I'm not sure if there's an easy way to determine this directly from the tz
> > files, but since the data is also parsed and distributed through various
> > platforms, languages, libraries, and tools, it's probably something you
> > could do externally. For example, you could probably write some Python
> > script with zoneinfo data, which originates from here.
>
> Those are the only two examples according to this C++ program:
>
> #include <chrono>
> #include <print>
>
> int main()
> {
> using namespace std::chrono;
> sys_days summer(2025y/6/21), winter(2025y/12/21);
> const auto& db = get_tzdb();
> std::println("{}", db.version);
> for (const auto& tz : db.zones)
> {
> auto info1 = tz.get_info(summer);
> auto info2 = tz.get_info(winter);
> if (info1.offset != info2.offset)
> {
> if (abs(info1.offset - info2.offset) != 1h)
> std::println("{} has offset {} in summer and {} in winter",
> tz.name(), info1.offset, info2.offset);
> }
> }
> }
>
> The output on my system was:
>
> 2025a
> Antarctica/Troll has offset 7200s in summer and 0s in winter
Of course, June is not summer and December is not winter in Australia, oops :)
Pretend I use June and December instead.
> Australia/Lord_Howe has offset 37800s in summer and 39600s in winter
