[Question] How to override a specific lsp config

[midnightexigent]

Hi,

I just found out about this project, very promising stuff

I am trying to customize the lsp config: I install rust-analyzer with the rustup nightly toolchain meaning that the command to run it is rustup run nightly rust-analyzer

Is there a way to configure helix so it runs that command for rust-analyzer?

[kirawi]

rust-analyzer needs to be present in your PATH environment variable. I don't think rustup adds it for you. If you want to configure LSPs in the future though, that's done through the languages.toml file.

[midnightexigent]

Thanks for the reply,

I tried that, but now I am encountering a different issue:

I put this in languages.toml

[[language]]
name = "rust"
language-server = { command = "rustup", args = ["run", "nightly", "rust-analyzer"] }
config = """
{
  "cargo": {
    "allFeatures": true,
  },
  "checkOnSave": {
    "command": "clippy",
  }
}
"""

But helix is not using the config I provided (I am not getting cargo clippy warnings)

[kirawi]

Try turning on logging via -v and then look at the log.

[midnightexigent]

I tried that, but the config payload is nowhere to be seen in the logs, there is just the capabilities. I also tried with -vvv but didn't get the information in the logs

[kirawi]

Seems like it doesn't work because the rustup process ends early.

[midnightexigent]

So is it a bug ? Or am I doing something wrong in the config ?

Also, changing back to

language-server = { command = "rust-analyzer" }

is no good either

[kirawi]

That's because rust-analyzer is not present in your PATH environment variable; rustup install rust-analyzer doesn't add it. You'll have to install it through some other method, such as a package manager or manually, because it's not yet possible to do with rustup (rust-lang/rustup#2411).

[midnightexigent]

Sorry, I meant that I tried this

language-server = { command = "rust-analyzer" }

with rust-analyzer in my PATH but the config wasn't being applied either.

Anyhow, I figured out the problem: the json parsing of the provided config was failing silently due to the trailing commas.

Since we're already in a toml file, shouldn't the config be passed in as a toml::Value rather than a json string ?

[kirawi]

No, it has to be JSON according to the LSP spec. As for trailing commas, we should probably be logging such errors https://github.com/serde-rs/json/blob/8604ef948bec5190db6fa23d362bd3368620990c/src/error.rs#L66

helix/helix-lsp/src/lib.rs

Line 321 in 05c2a72

serde_json::from_str(language_config.config.as_deref().unwrap_or("")).ok(),

I'll get it done later today.

[midnightexigent]

yes, I meant read it as a toml::Value from the config, and the convert it to a serde_json::Value, something like this

let toml_value: toml::Value = toml::from_str(r#"
    [config.cargo]
    allFeatures = true
    [config.checkOnSave]
    command = "clippy"
  "#).unwrap();

let json_value: serde_json::Value = toml_value.try_into().unwrap();

println!("{}", serde_json::to_string_pretty(&json_value).unwrap())

[kirawi]

This goes outside of what I know (I haven't worked with the LSP code), but I suspect that it's because converting from JSON to Toml didn't really make sense. This was brought up before in the past before this was implemented, and I guess we decided to stick with JSON.