problems with clangd 7

[justinmk]

(For reference, so others can find this)

clangd --version
clangd version 7.0.0-3~ubuntu0.18.04.1 (tags/RELEASE_700/final)

With the default clangd config from nvim-lsp:

~/.local/share/nvim/vim-lsp.log:

"rpc">  "clangd">       "stderr">       "clangd"
"rpc">  "clangd">       "stderr">       ": Unknown command line argument '"
"rpc">  "clangd">       "stderr">       "--background-index"
"rpc">  "clangd">       "stderr">       "'.  Try: '"
"rpc">  "clangd">       "stderr">       "clangd"
"rpc">  "clangd">       "stderr">       " -help'\n"
"rpc">  "clangd">       "stderr">       "clangd"
"rpc">  "clangd">       "stderr">       ": Did you mean '-"
"rpc">  "clangd">       "stderr">       "ppc-gen-isel"
"rpc">  "clangd">       "stderr">       "'?\n

That can be fixed by overriding cmd:

  local nvim_lsp = require 'nvim_lsp'              
  local util = require 'nvim_lsp/util'          
  nvim_lsp.clangd.setup {                                  
    cmd = {"clangd"},                                 
    root_dir = util.root_pattern('build/compile_commands.json', '.git'),
  }

Also note that Neovim puts build/compile_commands.json in "build" directory, so the root_dir is overridden there.

If I try to complete something in eval.c, this is the log result:

"I[16:01:24.764] Code complete: 0 results from Sema, 0 from Index, 0 matched, 0 returned.\n"
"I[16:01:24.764] --> reply(4)\n"         
"I[16:04:43.809] <-- textDocument/completion(5)\n"         
"I"         
"["         
"16:04:43.874"         
"] "         
"Code complete: Ignoring sema code complete callback with Recovery context."         
"\n"         
"I"         
"["         
"16:04:43.876"         
"] "         
"Code complete: "         
"0"         
" results from Sema, "         
"0"         
" from Index, "         
"0"         
" matched, "         
"0"         
" returned"         
"."         
"\n"         
"I"         
"["         
"16:04:43.879"         
"] "         
"--> reply("         
"5"                                                                                                                             
")"
"\n"

[justinmk]

With clangd version 8, some things work:

• --background-index
• inline diagnostics/warnings
• LSP log shows that "indexing" happened

But still can't get omnicompletion to work.

Edit: After installing latest Nvim and nvim-lsp, and restarting Nvim, omnicompletion works now. Yay!

TODO:

• We need an easy way for users to check the "status" of LSP.

[norcalli]

We could add an automatic check for clangd version on startup. This is something that I've been considering separately, which is that when a user uses our setup function, it doesn't check if you have the binary available. That means it will error when you try to use it.

We could, in on_new_setup(), check the clangd version and provide a more valuable error or change the arguments we pass.

[norcalli]

I was told by bfredl, though, that clangd 9 was the only one to have fixed most LSP things, though. I agree, we should put it in the docs that clangd 9 is required/recommended.

[justinmk]

After installing latest Nvim and nvim-lsp, and restarting Nvim, omnicompletion works now (with clangd version 8). Yay!