`None` treated like variable name in Option match

[lewoberst]

rust-analyzer version: rust-analyzer 0.3.2053-standalone

rustc version: rustc 1.79.0

editor or extension: neovim v0.9.5 (rust-analyzer installed by mason plugin, running on a debian stable installation)

code snippet to reproduce:

fn main() -> Result<(), ()> {
    let v = Some(false);                                                                             
    let _i = match v {
        Some(true) => 1,
        Some(false) => 2,
        None => 3,
    };
    Ok(())
}

"Variable None should have snake_case name, e.g. none [non_snake_case]" in line 6.

rust-analyzer prints that as a warning message for every Option match, also if None occurs within tuples. It doesn't make any sense to me. Other than that, rust-analyzer seems to be working fine as far as I can tell.

[lnicola]

Can't reproduce, does "Go to Definition" on Some work?

[lewoberst]

I assume you mean "Go to definition" on None? Doesn't move the cursor, no (and neither on Some).

[lnicola]

Sounds like you might be missing rust-src, can you check?

[lewoberst]

You are right and installing rust-src manually fixed it.

I would have expected rust-analyze to complain in a more direct, obvious way though. Also the documentation states "rust-analyzer will attempt to install it automatically", this did either not happen or not work and rust-analyzer wouldn't complain.

Should handling of that error be improved? Otherwise this issue can be closed. Thanks for helping out.

[cxw620]

I met with the same issue though with rust-src installed, and I fix it by adding the following to env:

export RUST_SRC_PATH="$(rustc --print sysroot)/lib/rustlib/src/rust/src"

From: https://gist.github.com/dearmark/90a7da8904111466b8b2c47d1678485b

[lnicola]

Also the documentation states "rust-analyzer will attempt to install it automatically", this did either not happen or not work

We run rustup component add rust-src, and it works fine for me. You didn't mention how you installed Rust. But Debian 12 doesn't come with 1.79. Did you use the standalone installer?

Should handling of that error be improved?

We should report that, see

rust-analyzer/crates/project-model/src/sysroot.rs

Line 479 in c9109f2

try installing the Rust source the same way you installed rustc",

:

But I think that's using an LSP extension, so it might not work with other clients. I'll file this as a follow-up issue.

I met with the same issue though with rust-src installed, and I fix it by adding the following to env:

We do the same thing at

rust-analyzer/crates/project-model/src/sysroot.rs

Line 436 in c9109f2

rustc.current_dir(current_dir).args(["--print", "sysroot"]);

, you shouldn't need to do anything.

[ferologics]

ran into the same issue on nightly-2024-10-19-aarch64-apple-darwin

$ rustup component list | rg installed
cargo-aarch64-apple-darwin (installed)
clippy-aarch64-apple-darwin (installed)
rust-docs-aarch64-apple-darwin (installed)
rust-src (installed)
rust-std-aarch64-apple-darwin (installed)
rustc-aarch64-apple-darwin (installed)
rustfmt-aarch64-apple-darwin (installed)

$ rustup component add rust-src
info: component 'rust-src' is up to date

the issue doesn't show up if I lint/check with clippy from terminal, only in VSCode:

[lnicola]

@ferologics does your project have a rust-toolchain.toml file? Does it happen in a new project?

[ferologics]

we do have a rust-toolchain.toml yes. i will try to repro in fresh project

[lnicola]

What does rust-toolchain.toml contain, and does that toolchain have rust-src installed?

[ferologics]

[toolchain]
channel = "nightly-2024-10-19"

yes, all the components listed above are for that toolchain override

[ferologics]

the issue does not reproduce in a fresh project cargo crate. i went ahead and reinstalled my toolchain, now the issue is gone. so maybe something went wrong during the first update. thanks for the quick followup @lnicola