How to show diagnostics for only the current line?

[Joedang]

I've been trying to work this out by reading the documentation/issues/discussions, but I need to finally cry uncle. Ultimately, I want to get the diagnostics, but I don't want them to cause the actual code to jump up and down the way g:lsp_diagnostics_virtual_text_enabled does. It really sounds like g:lsp_diagnostics_echo_cursor does what I want. However, I can't get it to do anything. (LspDocumentDiagnostics is close to what I want, except I don't want to sift through all diagnostics. I only want the ones for the current line.)

I tried creating a minimal .vimrc, removing all other plugins, and opening the minimal test file shown below. I would expect that if I leave my cursor on unused1 or unused2 and wait a half second, the statusline would then display the warning about the variable being unused. However, it just continues to show the filename of the buffer.

Does anyone have an idea of what I'm doing wrong? It seems like I must be missing something "obvious".

.vimrc:

set nocompatible " don't try to be compatible with Vi; required for Vundle

" make it obvious that the statusline is working:
hi StatusLineNC cterm=underline 
hi StatusLine cterm=bold ctermfg=white ctermbg=grey
set laststatus=2

"~~~~~~~~~~ LANGUAGE SERVER STUFF ~~~~~~~~~~
autocmd User lsp_setup call lsp#register_server({ 'name': 'Rust Language Server', 'cmd': {server_info->['rust-analyzer']}, 'allowlist': ['rust'] })

function! s:on_lsp_buffer_enabled() abort
	let g:lsp_diagnostics_enabled = 1
	let g:lsp_diagnostics_virtual_text_enabled = 0
	setlocal signcolumn = yes " make it obvious that diagnostics are working
	let g:lsp_diagnostics_echo_cursor = 1
endfunction

autocmd User lsp_buffer_enabled call s:on_lsp_buffer_enabled()

"~~~~~~~~~~ VUNDLE STUFF ~~~~~~~~~~
filetype off                  " required
set rtp+=~/.vim/bundle/Vundle.vim
call vundle#begin()
Plugin 'VundleVim/Vundle.vim'
Plugin 'prabirshrestha/vim-lsp'
call vundle#end()            " required
filetype plugin indent on    " required

src/main.rs

fn main() {
    let unused1 = 0;
    let unused2 = 0;
}

screenshot (cursor is on unused1):

Vim version:

$ vim --version                                                                                                                        
VIM - Vi IMproved 9.1 (2024 Jan 02, compiled May 26 2024 00:11:37)                                                                      
Included patches: 1-445                                                                                                                 
Compiled by Arch Linux                                                                                                                  
Huge version without GUI.  Features included (+) or not (-):                                                                            
+acl               +file_in_path      +mouse_urxvt       -tag_any_white                                                                 
+arabic            +find_in_path      +mouse_xterm       +tcl/dyn                                                                       
+autocmd           +float             +multi_byte        +termguicolors                                                                 
+autochdir         +folding           +multi_lang        +terminal                                                                      
-autoservername    -footer            -mzscheme          +terminfo                                                                      
-balloon_eval      +fork()            +netbeans_intg     +termresponse                                                                  
+balloon_eval_term +gettext           +num64             +textobjects                                                                   
-browse            -hangul_input      +packages          +textprop                                                                      
++builtin_terms    +iconv             +path_extra        +timers                     
+byte_offset       +insert_expand     +perl/dyn          +title                      
+channel           +ipv6              +persistent_undo   -toolbar                    
+cindent           +job               +popupwin          +user_commands                                                                                                                                                            
-clientserver      +jumplist          +postscript        +vartabs                                                
-clipboard         +keymap            +printer           +vertsplit                                              
+cmdline_compl     +lambda            +profile           +vim9script                                                                                                                                                               
+cmdline_hist      +langmap           -python            +viminfo                                                
+cmdline_info      +libcall           +python3/dyn       +virtualedit                                                                                                                                                              
+comments          +linebreak         +quickfix          +visual
+conceal           +lispindent        +reltime           +visualextra
+cryptv            +listcmds          +rightleft         +vreplace
+cscope            +localmap          +ruby/dyn          +wildignore 
+cursorbind        +lua/dyn           +scrollbind        +wildmenu
+cursorshape       +menu              +signs             +windows
+dialog_con        +mksession         +smartindent       +writebackup
+diff              +modify_fname      -sodium            -X11
+digraphs          +mouse             -sound             +xattr
-dnd               -mouseshape        +spell             -xfontset
-ebcdic            +mouse_dec         +startuptime       -xim
+emacs_tags        +mouse_gpm         +statusline        -xpm
+eval              -mouse_jsbterm     -sun_workshop      -xsmp
+ex_extra          +mouse_netterm     +syntax            -xterm_clipboard
+extra_search      +mouse_sgr         +tag_binary        -xterm_save 
-farsi             -mouse_sysmouse    -tag_old_static    
   system vimrc file: "/etc/vimrc"
     user vimrc file: "$HOME/.vimrc"
 2nd user vimrc file: "~/.vim/vimrc"
 3rd user vimrc file: "$XDG_CONFIG_HOME/vim/vimrc"
      user exrc file: "$HOME/.exrc"
       defaults file: "$VIMRUNTIME/defaults.vim"
  fall-back for $VIM: "/usr/share/vim"
Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H -march=x86-64 -mtune=generic -O2 -pipe -fno-plt -fexceptions -Wformat -Werror=format-security -fstack-clash-protection -fcf-protection -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -g -ffile-prefix-map=/build/vim/src=
/usr/src/debug/vim -flto=auto -D_REENTRANT -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1                                                        
Linking: gcc -Wl,-E -Wl,-rpath,/usr/lib/perl5/5.38/core_perl/CORE -Wl,-O1 -Wl,--sort-common -Wl,--as-needed -Wl,-z,relro -Wl,-z,now -Wl,-z,pack-relative-relocs -flto=auto -L/usr/local/lib -o vim -lm -ltinfo -lelf -lacl -lattr -lgpm -L/usr/lib -ltclstub8.6 -ldl -lz -lpthre
ad -lm                                                              

[ernstki]

This will probably work for you. Basically, don't put the let statements inside s:on_lsp_buffer_enabled()—although to be honest, that's exactly what I tried, too. Try this instead:

" copy-pasted from https://github.com/prabirshrestha/vim-lsp#registering-servers
augroup lsp_install
    au!
    " call s:on_lsp_buffer_enabled only for languages that has the server registered.
    autocmd User lsp_buffer_enabled call s:on_lsp_buffer_enabled()

    " ref: https://github.com/prabirshrestha/vim-lsp/discussions/1560
    "let g:lsp_diagnostics_float_cursor = 1
    let g:lsp_diagnostics_echo_cursor = 1
    let g:lsp_diagnostics_virtual_text_enabled = 0
augroup END

Uncomment let g:lsp_diagnostics_float_cursor = 1 to see if you like that better than it appearing in the status line. You can enable both, but I don't know why anyone would want to.

References

• Not seeing floating window with g:lsp_diagnostics_float_cursor=1 #1040 (comment)