How do I determine whether the current month is June according to the user's system time zone?

[teohhanhui]

My use case is just checking the current "local" date / time, not going to store/send it in any way and/or perform any arithmetic on it.

Specifically, the question in my case is: "Is it June now?" (as defined by the user's system)

I have been unable to find anything that would let me do that without doing the unnecessary work of looking up the IANA timezone in the tzdb, but perhaps I'm just missing the obvious?

[BurntSushi]

Zoned::now().month() == 6 is exactly the correct answer to whether it is June, according to the user's system.

time is doing the same work. It's just farming it out to libc. libc in this case will probably open /etc/localtime and use that file directly to determine the time zone transitions. Jiff will do something a little smarter and look for the tzid in the symlink of /etc/localtime, and then go look that time zone up in /usr/share/zoneinfo (which is where /etc/localtime is linked to anyway). So Jiff isn't really doing any extra work here as far as I can tell. And the /etc/localtime inspection is cached.

[teohhanhui]

IIUC, this would require the bundled tzdb on Windows, right? Even though (I believe) I only need the Bias from DYNAMIC_TIME_ZONE_INFORMATION

[BurntSushi]

I believe that is correct, yes. The only thing Jiff pulls from DYNAMIC_TIME_ZONE_INFORMATION is the TimeZoneKeyName.

[teohhanhui]

I see time uses SystemTimeToTzSpecificLocalTime: https://github.com/time-rs/time/blob/aca5c3652aff6fc7df3fbd8591c3e324d3a6ffb2/time/src/sys/local_offset_at/windows.rs#L92C17-L92C48

As it seems that helps avoid bundling tzdb on Windows, I'll stick to that for now considering my very specific use case.

But it's good to know that the design of this crate is well-considered.

[teohhanhui]

Thank you for the explanation and sorry for the noise. I realize this should have been a Q&A in the discussions instead.

[BurntSushi]

Done. I converted it. :-) Thankfully GitHub makes that easy.