Allow rust path configuration

[yaymalaga]

In Rust (rls) vscode extension, it is possible to specify the rustup path by adding the "rust-client.rustupPath" key in the settings.json.

Would it be possible to have the same option in rust-analyzer? This would enable the extension to directly know about the location of cargo, rustc, etc

[bjorn3]

rust-analyzer never invokes rustup itself.

https://github.com/rust-analyzer/rust-analyzer/search?q=rustup&unscoped_q=rustup

[yaymalaga]

I was thinking about Cargo binary, as it is in the same folder as rustup if intalled using that tool. I have changed the title, thanks!

[kiljacken]

If I'm allowed to be a little snarky, we already have this, it's called the PATH enviroment variable :)

I'm not sure if I personally see too much value adding another way to configure it (not really any harm either, apart from added complexity of threading the configuration through to where it's needed) , I'd love if you shared your use case, as it makes it easier to evaluate :)

[matklad]

I think we should honor RUSTC and CARGO env variables (and we already honor the later, via cargo metadata), but an explicit config does seem like an overkill to me.

[matklad]

This is the place where we need to take RUSTC into account: https://github.com/rust-analyzer/rust-analyzer/blob/58f4dcf79ecf3b8dcec83d46a27a29340900a0ef/crates/ra_project_model/src/lib.rs#L430

[yaymalaga]

In my case, this issue would be related to how vscode works in Solus (Linux distro), as explained in microsoft/vscode-python#1338 (comment).

In short, the path that vscode is using internally (not happening in its embedded terminal) does not take into account the user-configured one, so that's why I had to manually add rustup path in Rust-rls extension to make it work. Therefore, with this extension I'm getting an error when it executes cargo metadata, as it is not found.

[lnicola]

@yaymalaga see #2496 (comment).

We had something about this in the install notes, but it was dropped in #3140.

[SomeoneToIgnore]

One more rustc place that needs to be taken care of in this issue: https://github.com/rust-analyzer/rust-analyzer/blob/585eef1d8c79e24b7788363cf3a5bc7c9c3bc963/crates/ra_project_model/src/sysroot.rs#L112

Also now we call rustup once here, to install rust-src when we don't find it: https://github.com/rust-analyzer/rust-analyzer/blob/585eef1d8c79e24b7788363cf3a5bc7c9c3bc963/crates/ra_project_model/src/sysroot.rs#L118
There's no environment variable for rustup, so we need to come up with something else if we plan to change this place either.
Yet it seems that for cases when it's impossible to add rustup to the path, it's better to install rust-src manually also.

There are also two places in rust-analyzer's coe that might need a fix either, but I'm not sure:

• https://github.com/rust-analyzer/rust-analyzer/blob/93d28fb50c8496d00bfb457a42fb5ee66f83d7b5/crates/ra_lsp_server/src/main_loop/handlers.rs#L592
• https://github.com/rust-analyzer/rust-analyzer/blob/d400fde66c7139aad04e5c5c9875a1d41ef5eae8/crates/ra_cargo_watch/src/lib.rs#L273