Weird behavior with tab mapping

[stefanos82]

I have custom mapping for tab key

" Use Tab to select completion downwards when popup window opened
inoremap <silent><expr> <TAB> pumvisible() ? "\<C-n>" : "\<TAB>"
" Use Tab to select completion upwards when popup window opened
inoremap <expr> <S-TAB> pumvisible() ? "\<C-p>" : "\<S-TAB>"
inoremap <expr> <cr> pumvisible() ? "\<C-y>" : "\<cr>"

and when I have it disabled, that is completely commented out, I get no mapping found with :verbose imap <tab>, but as soon as I uncomment it, I get

i  <Tab>       * coc#pum#visible() ? coc#pum#next(1) : "\<Tab>"                                  
        Last set from ~/.vim/pack/plugins/start/coc.nvim/autoload/coc/ui.vim line 23

Without my own version of mapping, I cannot use vim-go at all; it does not accept the Enter key to accept the current highlighted / selected word, nor it accepts the tab key of course.

I'm really confused...

I have even tried your own suggestion from README

" Use tab for trigger completion with characters ahead and navigate
" NOTE: There's always complete item selected by default, you may want to enable
" no select by `"suggest.noselect": true` in your configuration file
" NOTE: Use command ':verbose imap <tab>' to make sure tab is not mapped by
" other plugin before putting this into your config
inoremap <silent><expr> <TAB>
      \ coc#pum#visible() ? coc#pum#next(1) :
      \ CheckBackspace() ? "\<Tab>" :
      \ coc#refresh()
inoremap <expr><S-TAB> coc#pum#visible() ? coc#pum#prev(1) : "\<C-h>"

" Make <CR> to accept selected completion item or notify coc.nvim to format
" <C-g>u breaks current undo, please make your own choice
inoremap <silent><expr> <CR> coc#pum#visible() ? coc#pum#confirm()
                              \: "\<C-g>u\<CR>\<c-r>=coc#on_enter()\<CR>"

function! CheckBackspace() abort
  let col = col('.') - 1
  return !col || getline('.')[col - 1]  =~# '\s'
endfunction

and obviously does not work with vim-go at all; it makes things worse of course.

If there a way to tell coc.nvim to allow me use my own custom mapping for Golang only?

[fannheyward]

Check :h coc_disable_mappings_check

[stefanos82]

I forgot to mention that I have tried this approach and of course, my custom mapping works, but this way I lose coc.nvim's auto-completion benefits.

[fannheyward]

You need to setup mappings to use coc.nvim functions. As far as I know, vim-go didn't remap the tab key, what do you mean does not work with vim-go at all? You can use coc.nvim and vim-go both at the same time.

[stefanos82]

Let me show you what's the problem I'm facing.

I have the following mapping for tab:

" Use Tab to select completion downwards when popup window opened
inoremap <silent><expr> <TAB> pumvisible() ? "\<C-n>" : "\<TAB>"
" Use Tab to select completion upwards when popup window opened
inoremap <expr> <S-TAB> pumvisible() ? "\<C-p>" : "\<S-TAB>"
inoremap <expr> <cr> pumvisible() ? "\<C-y>" : "\<cr>"

If I disable this and leave coc.nvim as it is configured, auto-completion works with coc.nvim, but cannot choose anything either with tab key or Enter.

if I disable coc.nvim with let g:coc_disable_mappings_check = 1 and enable my aforementioned custom tab mapping, it works in vim-go as expected, but now the problem switches to coc.nvim, meaning the previous problematic vim-go behavior takes place in coc.nvim instead!

I'm trying to find the golden ratio to make both of them work, with each its own configuration settings.

[stefanos82]

As I have stated above to previous thread window(s), the coc-completion-example affects my editor's performance; it makes my CPU go crazy for a number of seconds. I simply cannot use my computer until it finishes with whatever it's doing.

That is not the case when I use my custom mapping along with coc.nvim.

[fannheyward]

Can't reproduce the performance issue. Try to add the mapping from coc-completion-example only what you need to your vimrc, not the whole configuration.

[stefanos82]

I have and caused the problems I have mentioned.

[fannheyward]

Can't reproduce the issue in my tests, try minimal vimrc, only coc.nvim plugin + coc.nvim's mappings.

[stefanos82]

Anyway, I will continue with the current setup I have and it will be alright.

Thank you very much.

[stefanos82]

@fannheyward Seems like I was very tired to see the right solution to my problem.

I did not need to set a custom mapping; just creating a "bridge" between coc.nvim settings and vim-go worked flawlessly.

Here's the missing part in :CocConfig settings on my side that fixed the problematic behavior:

"golang": {
    "command": "gopls",
    "rootPatterns": ["go.mod", ".git/"],
    "filetypes": ["go"]
}

and the necessary vim-go flags to match the desired output:

let g:go_highlight_fields = 1
let g:go_highlight_build_constraints = 1
let g:go_highlight_types = 1
let g:go_highlight_extra_types = 1
let g:go_highlight_format_strings = 1
let g:go_highlight_functions = 1
let g:go_highlight_function_calls = 1
let g:go_highlight_function_parameters = 1
let g:go_highlight_operators = 1
let g:go_highlight_variable_declarations = 1

let g:go_code_completion_icase = 1
" Disable GoDoc
let g:go_doc_keywordprg_enabled = 0

This works wonders!