workspace/executeCommand not supported

[JeanMertz]

The lsp-features.md file mentions that workspace/executeCommand is supported (specifically, apply_code_action):

https://github.com/rust-analyzer/rust-analyzer/blob/a71d0ecd774008bbfe8cb2215ffa6dedd5024877/docs/dev/lsp-features.md#L19-L20

I want to make rust-analyzer code actions work in Vim by updating LanguageClient-neovim, but from what I can tell, workspace/executeCommand is not actually supported anymore?

I can see the handle_execute_command handler being removed in 8abf536#diff-43d4f175343e385858e9f5a752c17d57L370.

Instead, from what I understand, I have to do a textDocument/codeAction request, pick one of the actions to perform, match on the rust-analyzer.applySourceChange command, and then parse the arguments data to apply the changes locally on the client:

https://github.com/rust-analyzer/rust-analyzer/blob/a71d0ecd774008bbfe8cb2215ffa6dedd5024877/crates/ra_lsp_server/src/main_loop/handlers.rs#L630-L633

Are my assumptions correct? If so, then I'll start adding this feature to Vim, and I guess it would make sense to uncheck the box in the supported features list, right?

[matklad]

Yeah, right, rust-analyzer.applySourceChange should be supported by the client.

We need microsoft/language-server-protocol#724 to switch to build-in facilities for our code actions

[kjeremy]

Would it be better to move applySourceChange into the server and implement workspace/executeCommand and workspace/applyEdit?

[matklad]

@kjeremy we can't do that because, because:

• we can't tell the client to open specific file (needed for unresolved modle fix)
• we can't tell the client about cursor position (needed for many intentions like add derive)

Ideally, we extend LSP with support for those use-cases, yeah.

[JeanMertz]

When adding support for this in Vim, I noticed that the client already had something similar implemented for the/a Java language server.

So apparently it's not unprecedented to leave it up to the clients to handle this (probably for the same reasons you mentioned, @matklad, the LSP spec does not provide the flexibility needed in this case).

[lnicola]

This can be closed, I think?

[matklad]

right, we don't intend to have server-side commands.

[jan-xyz]

Do I understand this right, that this is a custom implementation needed in every client? I'm coming from Neovim and basically can't use any of the code lenses (Run Test, Debug...) because it's considered a "custom extension/handler" (neovim/neovim#14874 (comment)) and it needs custom implementation. If that's true then it's quite sad and we are again at a point pre-LSP where each editor needs to provide custom code to fully support some features (albeit much less then before).

[matklad]

@jan-xyz you need https://github.com/simrat39/rust-tools.nvim to gain access to rust-analyzer specific extensions in neovim. If you want to see our extensions upstreamed into the protocol, show your support for corresponding issues on the lsp repo: https://github.com/microsoft/language-server-protocol/issues/created_by/matklad

[jan-xyz]

Thanks for your reply, I played around with rust-tools and it covers at least some aspect ( I can run individual tests 🤗 ) but the code lenses aren't implemented, I guess I vote and hope that Microsoft will hear our plea...

[matklad]

( I can run individual tests hugs ) but the code lenses aren't implemented,

If this is about this functionality:

then the situation here is even more confusing. What we do here is entirely standard LSP, but still requires custom support from the client. Basically, in the LSP code lens contains a string name of the command to be executed by the client (like "rust-analyzer.runSingle"), and that command needs to be implemented by the client. That is, the way LSP is specced here is "invoke this custom command on the client side".

This particular feature really should have first-class support in the protocol, upstream issue is microsoft/language-server-protocol#944

[jan-xyz]

Yes! That's the functionality, did I comment on the wrong issue? Since Neovim invokes workspace/executeCommand when I run those code lenses, I thought this is related to this issue.

So what a plugin like rust-tools needs to do is implement rust-analyser.runSingle on the built-in client?

[matklad]

Aha, my understanding is that shouldn't be happening, opened neovim/neovim#15183 for that.