Use of chrono::offset::local::now() ignores the Windows 10's time zone

[Clauvin]

What's Happening

When I use chrono::offset::local::now() in an ambient program, it returns a date and time that does not have the time zone of the computer where the program runs, instead the time zone returned is +0.

Where's Happening

In a PC with Windows 10, in an Ambient program using as dependencies

ambient_api = "0.2.1" more-asserts = "0.3.1" chrono = "0.4.26"

AND it shows up at the first person camera example (see Extra Commentary, below). May be happening on other programs as well, more testing is required.

How to Reproduce

• In a computer running Windows 10, make sure that the time zone used by it is not UTC+0;
• Create two projects: one using Ambient 0.2.1 and other that's just a Rust project, without Ambient, by cargo new;
• Add to both projects the chrono = "0.4.26" dependency;
• Add use chrono::prelude::*; to the Ambient project's client.rs and the Rust project's main.rs;
• Add println!("{:?}", Local::now());to both project's main function.
• Run both projects through the command prompt;
• The ambient log printed on the command prompt should have a line ending with something similar to this in structure: 2023-06-21T02:21:19.425459200+00:00, emphasis on the end +00:00.
• The rust program should also print a line with a similar structure, but with a different time, maybe a different date depending of the time zone, and explictly a different end on the line, that is the time zone of the OS;

Extra Commentary

This (or a similar bug) can also be visible at the Ambient's log lines - each log line starts with a [, then the date, time and time zone of when it was printed - running the Ambient program where this bug appeared and also the first person camera example revealed the same problem regarding the wrong date and time at each line:

[2023-06-21T02:29:45Z INFO ambient] Building First person camera [2023-06-21T02:29:46Z INFO ambient] Done building First person camera [2023-06-21T02:29:46Z INFO ambient::server] Creating server

The three date and time above are using UTC+0, but it should be using UTC-3.

[philpax]

Thanks for reporting this!

It looks like it's two issues:

• the Ambient app's log formatting defaults to printing in UTC time
• the guest code does not know what the timezone is, and defaults to UTC

With 1), we'll have to research the going standard across applications to see which timezone our logs should be in. I suspect UTC is better for servers, but localtime is better for usability (i.e. I can see the mdbook server is giving me local time, but you wouldn't run that in production)

For 2), this appears to be a consequence of wasmtime-wasi not supporting timezones yet: https://github.com/bytecodealliance/wasmtime/blob/a43d1dc68fc24e71f726ec858db90f1731e96a11/crates/wasi/src/preview2/preview2/clocks.rs#L63-L80

I'm not sure when this will be fixed, but I believe this will just "start working" once that's available and the preview1-on-2 adapter is adapted for it. I'll keep this issue open until then 🙂

[Clauvin]

Right, thanks 🙂