P0355R7 <chrono> Calendars And Time Zones

[microsoft]

P0355R7 Calendars And Time Zones

from stl.

[SuperWig]

Well I've started working on it anway because I have too much free time on my hands and it's a fun learning experience 🤷‍♂

[SuperWig]

Is someone working on this? I think I could partially implement this.
Though isn't this partially dependant on #30?

[StephanTLavavej]

We haven't started working on this. Be aware that it's a major feature, one of the largest in C++20.

Yep, WG21-P1361 "Integrating <chrono> With <format>" links them (it's not a major dependency, as I understand it).

One of the things that we were planning to do is evaluate whether we should attempt to implement this from scratch, or incorporate an existing implementation. libc++'s implementation is in progress (according to their hopefully-accurate status page), while Howard Hinnant (the designer of chrono, and the original author of libc++) has an implementation of this feature, but we'd need to work out licensing.

[SuperWig]

Be aware that it's a major feature, one of the largest in C++20.

That's why I said partially ;). Though having had a quick look at what libc++ has implemented so far it's not a whole lot more that I was considering on implementing.

(basically, not the clocks and I/O/formatting)

[SuperWig]

@StephanTLavavej Quick question, when the standard says "Returns: expression" I shouldn't deviate from that at all, right?

[StephanTLavavej]

Actually, the Standard’s As If Rule says that you can do anything you want, as long as the observable effects are “as if” you did exactly what the Standard says. For a Returns element (or the stronger Effects: Equivalent To), you generally should do what it says verbatim (with appropriate qualification etc.), but sometimes it is faster or better to do something different. If you do something different, you should comment it and/or call it out in your commit notes.