error processing hover event

[uberjay]

I can't seem to get any features from the lsp-ui package to work. I'm using the lsp-rust backend, which does work with the basic lsp-mode functionality. (e.g., M-., M-?, and inline syntax checking with flycheck.)

However, when I enable lsp-ui-mode in a buffer, I (after a short delay) get an error. Toggling debug-on-error gives me this backtrace:

Debugger entered--Lisp error: (wrong-type-argument lsp--workspace nil)
  signal(wrong-type-argument (lsp--workspace nil))
  lsp--on-hover()
  eldoc-print-current-symbol-info()
  #f(compiled-function () #<bytecode 0x400f0c33>)()
  apply(#f(compiled-function () #<bytecode 0x400f0c33>) nil)
  timer-event-handler([t 0 0 500000 nil #f(compiled-function () #<bytecode 0x400f0c33>) nil idle 0])

I thought it might have something to do with my multi-binary + library crate, so I switched over to a single binary crate with a single source file and have the same issues.

I'm using the emacs-mac build as of yesterday:

GNU Emacs 26.1 (build 1, x86_64-apple-darwin17.5.0, Carbon Version 158 AppKit 1561.4) of 2018-05-20

I've poked around the customize groups for lsp-ui (and its sub-features) and didn't see anything obvious that I needed to configure, so... I'm out of ideas! You've got several demos indicating that these features ought to be working for me with rust-mode, so perhaps it's a macOS-specific issue, or a regression with rls.

[yyoncho]

This error is not in lsp-ui but in lsp-mode. I suspect is it caused by an error in workspace initialization.

[uberjay]

Yeah, in fact... I only get this error when disabling and re-enabling lsp-ui-mode, so maybe some state isn't getting re-initialized correctly. Now... I guess maybe I'm missing something. I believe I have lsp-ui enabled correctly, but none of its features appear to be working. Am I missing something obvious? Do I have to do anything to make use of the sideline or doc child-frame features?

According to M-x describe-mode, everything ought to be enabled, yet nothing appears to be displayed.

lsp modes shown in the "Enabled minor modes" list:

Lsp Lsp-Ui Lsp-Ui-Doc Lsp-Ui-Sideline

[yyoncho]

You are getting this error after disabling lsp-ui-mode because disabling the lsp-ui-mode enables eldoc-mode(the support for eldoc is in lsp-mode. As I mentioned in my previous comment probably your Rust language server is not starting. In order to check why this is happening you could run (lsp-rust--rls-command) and then try to to run the returned command in terminal.

[uberjay]

Ok, interesting. Turns out, this may all be caused by using sccache. I had

export RUSTC_WRAPPER=sccache

Set in my env, which seems to get in the way of rls functioning correctly. So, for the time being I've created a wrapper script which unsets RUSTC_WRAPPER and execs rls, and have configured lsp-rust to use it:

  (setq lsp-rust-rls-command '("rls-run"))

And, it works! Now I can actually get around to trying it out and tweaking the configuration to my liking, instead of being incredibly confused why it wasn't working. I ended up finding some errors in the *lsp-rust stderr* buffer:

{"message":"multiple input filenames provided","code":null,"level":"error","spans":[],"children":[],"rendered":"error: multiple input filenames provided\n\n"}

...which helped me find this open rls issue:

rust-lang/rls#703

Thanks for your help pointing me in the right direction. :)