Consider updating to `wasi v0.13.1+wasi-0.2.0`

[LikeLakers2]

Hi! I noticed that getrandom appears to be using wasi v0.11.0+wasi-snapshot-preview1. The latest version of wasi is wasi v0.13.1+wasi-0.2.0.

I would normally recommend updating getrandom to use wasi v0.13 (newer versions are almost always better). However, I took a quick look at wasi's repository, specifically their readme, and found that wasi itself recommends staying on v0.11 in certain circumstances.

Still, I'm hesitant to simply assume that the getrandom developers know of any of this - and in any case, I didn't see issues or PRs with information on why getrandom isn't using a newer version. So, I wanted to make this issue. If nothing else, it'll be an opportunity to explain why getrandom isn't using a newer version.

Thank you in advance.

[newpavlov]

IIUC the wasm32-wasi target uses the preview1 API, so we should keep using wasi v0.11 on it and wasip1 targets. Meanwhile, wasi v0.13 should be used for wasip2 targets.

But I am not sure what value target_os has on wasm32-wasi, wasm32-wasip1, and wasm32-wasip2. Is it wasi, wasip1, and wasip2? Or wasi for all of them? If it's the latter, I think we have a problem...

[yoshuawuyts]

Hey all; I was asked to jump in here and answer this question. We thought WASI 0.2 would land as tier-2 stable in Rust 1.81 (September), but it will be landing in Rust 1.82 instead (November). The right way to target the different WASI flavors is as follows:

 // target WASI 0.1
 #[cfg(all(target_os = "wasi", target_env = "p1"))]
 mod wasip1 {
     // items go here
 }

 // target WASI 0.2
 #[cfg(all(target_os = "wasi", target_env = "p2"))]
 mod wasip2 {
     // items go here
 }

You can try this out today with the beta channel. I hope this helps!