Pain of 3 hours to configure rust-analyzer and what can be done better

[rusty-snake]

helix 23.10 (f6021dd) from Fedora 39 package repositories.

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I recently switched to helix, rust-analyzer worked out of the box and I am quite happy with it. Now I wanted to configure rust-analyzer to use clippy and other imports.granularity.group which got much more complicated than it should be.

The wiki has an example language.toml snippet to use clippy. Unfortunately this snippet does not work. Documentation and Wikis can become outdated so I started debugging this.

Finding the correct format by reading documentation did not worked. Besides the wiki I did not found much documentation how the config of a language server is build. And searching for other snippets in the internet and in Issues and Discussions gives more outdated confusion that it helps.

So I had to go with good old trail-and-error. Change languages.toml and see what happens. Sounds simple, but it is not because :config-reload+:lsp-restart can not be used to test although it looks like they are the right commands. :lsp-restart restarts rust-analyzer so any change initilalizationOptions should be used (this command works as expected). And :config-reload re-reads languages.toml. You can prove that languages.toml is re-read because a syntax error will make :config-reload to dump a error message. However, at least anything under language-server.rust-analyzer.config is not updated by :config-reload. You have to actually restart helix which is very unexpected. After realizing how I can actually test a changed langauges.toml after 2hours it got quick.

So back to the original problem. The snippet from the wiki is almost correct, but the stated behaviour of language-server.rust-analyzer.config.check.command => rust-analyzer.check.command is wrong. You have to use the full key (i.e. language-server.rust-analyzer.config.rust-analyzer.check.command) to make it work.

What can be done better

• Fix the example in the wiki
• Better document how language-server.*.config works. In the best case with a lot of examples in addition to a reference.
• Make :config-reload behave in a expected way.

[kirawi]

[language-server.rust-analyzer.config]
check.command = "clippy"

does work (I just tested).

I think the reason that it doesn't reload the language config is because Registrys reference to the config is never updated to the new one (the old shared pointer is dropped instead of the contents being replaced). That does seem like a bug,