rust-analyzer no longer supports workspace/executeCommand

[leotaku]

Describe the bug
When trying to apply a code action using lsp-execute-code-action using a recent version of rust-analyzer, the command fails with the following error message:

The connected server(s) does not support method workspace/executeCommand
To find out what capabilities support your server use ‘M-x lsp-describe-session’ and expand the capabilities section.

To Reproduce

1. Install rustup rustup 1.21.1
2. Install a nightly Rust toolchain using rustup. cargo 1.46.0-nightly
3. Install rust-analyzer using cargo rust-analyzer 36840bd
4. Load the following code in a clean Emacs instance. (Ensure that you have either set CARGO_HOME, or replace it with your OS's default location)

Click to expand!

(require 'package)

(setq debug-on-error t)

(let* ((package-archives '(("melpa" . "https://melpa.org/packages/")
                           ("gnu" . "https://elpa.gnu.org/packages/")))
       (no-byte-compile t)
       (package-user-dir (expand-file-name (make-temp-name "lsp-tmp-elpa")
                                           user-emacs-directory))
       (custom-file (expand-file-name "custom.el" package-user-dir))
       (pkg-list '(rust-mode lsp-mode lsp-ui yasnippet lsp-java lsp-python-ms lsp-haskell helm-lsp lsp-treemacs dap-mode lsp-origami lsp-dart company flycheck)))

  (package-initialize)
  (package-refresh-contents)

  (mapcar (lambda (pkg)
            (unless (package-installed-p pkg)
              (package-install pkg))
            (require pkg))
          pkg-list)

  (yas-global-mode)
  (add-hook 'prog-mode-hook 'lsp)
  (add-hook 'kill-emacs-hook `(lambda ()
                                (delete-directory ,package-user-dir t))))

(setq lsp-rust-server 'rust-analyzer)
(setq lsp-rust-analyzer-server-command
      (concat (getenv "CARGO_HOME") "/bin/rust-analyzer"))

5. Open any Rust file that is part of a cargo project.
6. Try running lsp-execute-code-action where a code action is advertised

Expected behavior

It would be unreasonable to expect this to work as rust-analyzer has lost support for workspace/executeCommand quite a while ago. (rust-analyzer/#1232)

I would argue that lsp-mode should support the server-specific rust-analyzer.applySourceChange capability, as other client implementations (vim, kakoune) already do the same. Though I realize that this could represent additional maintenance burden. (@brotzeit and @kurnevsky, what do you think?)

I also think that as long as we do not support applying the changes suggested by rust-analyzer they should not be by suggested as part of the modeline, lsp-ui or the lsp-execute-code-action minibuffer selection.

Which Language Server did you use

lsp-rust with rust-analyzer

OS
NixOS Linux 20.09pre-git (Nightingale)

[yyoncho]

I will do a fix.

[yyoncho]

@leotaku can you give an example for code action that does not work? I tested a few and they seems to work fine when using this version: https://github.com/rust-analyzer/rust-analyzer/releases/tag/2020-07-06

[leotaku]

Sure, all code actions I tried seemed to fail, so I did not specify one.

• Add #[derive]
• Add default constructor

These are advertised for all structs and should be easy to reproduce.

[yyoncho]

Sorry, I am not using rust on day to day basis, can you provide sample file to reproduce the issue?

[flodiebold]

rust-analyzer.applySourceChange is not needed by current rust-analyzer versions. Try updating your rust-analyzer (the commit you reference is 3 months old).

[leotaku]

@flodiebold is correct, I did not have an up-to-date version of rust-analyzer installed. I honestly did not give it much thought, as I did not see any newer PRs/commits referencing the issue in rust-analyzer but saw very recent commits in e.g. kak-lsp that indicate they had to use custom logic.

@flodiebold do you by any chance have a link to the issue where this new development is discussed? Is there any reason to still support rust-analyzer.applySourceChange?

@yyoncho Thanks for trying to step in so quickly! I am sorry for any confusion caused by my issue.

[flodiebold]

No, there's no reason to support applySourceChange anymore. It was removed as part of an effort to move to extensions that can potentially be upstreamed to the protocol, which you can read about here.

(Note that lsp-mode used to have support for applySourceChange. I removed it, because it's not needed anymore.)

[leotaku]

Thanks @flodiebold. In that case I think it makes sense to just close this issue.