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
Australia/Lord_Howe has offset 37800s in summer and 39600s in winter
