Golang NeoVim Autocomplete Config

init.vim

call plug#begin('~/.vim/plugged')

Plug 'prabirshrestha/asyncomplete.vim'
Plug 'prabirshrestha/asyncomplete-gocode.vim'
Plug 'prabirshrestha/async.vim'
Plug 'prabirshrestha/vim-lsp'
Plug 'prabirshrestha/asyncomplete-lsp.vim

call plug#end()

" Plugin: 'prabirshrestha/asyncomplete.vim'
" Tab completion
inoremap <expr> <Tab>   pumvisible() ? "\<C-n>" : "\<Tab>"
inoremap <expr> <S-Tab> pumvisible() ? "\<C-p>" : "\<S-Tab>"
inoremap <expr> <cr>    pumvisible() ? "\<C-y>" : "\<cr>"

" refresh suggestions on backspace
function! s:check_back_space() abort
    let col = col('.') - 1
    return !col || getline('.')[col - 1]  =~ '\s'
endfunction

inoremap <silent><expr> <TAB>
  \ pumvisible() ? "\<C-n>" :
  \ <SID>check_back_space() ? "\<TAB>" :
  \ asyncomplete#force_refresh()
inoremap <expr><S-TAB> pumvisible() ? "\<C-p>" : "\<C-h>"
set completeopt+=preview
autocmd! CompleteDone * if pumvisible() == 0 | pclose | endif

" https://github.com/prabirshrestha/asyncomplete.vim#language-server-protocol-lsp
if executable('gopls')
    " pip install python-language-server
    au User lsp_setup call lsp#register_server({
        \ 'name': 'gopls',
        \ 'cmd': {server_info->['gopls']},
        \ 'whitelist': ['go'],
        \ })
endif

" https://github.com/prabirshrestha/asyncomplete-gocode.vim
call asyncomplete#register_source(asyncomplete#sources#gocode#get_source_options({
    \ 'name': 'gocode',
    \ 'whitelist': ['go'],
    \ 'completor': function('asyncomplete#sources#gocode#completor'),
    \ 'config': {
    \    'gocode_path': expand('~/go/bin/gocode')
    \  },
    \ }))