Vim-go: doc: vim-go + deoplete + deplete-go + gopls

[dnwe]

What did you do? (required. The issue will be closed when not provided.)

Upgraded to latest vim-go and wanted to experiment with the new gopls completion

What did you expect to happen?

I expected gopls to be used for both the built-in omnifunc binding () and the . real-time completion from deoplete/deoplete-go

What happened instead?

I found that gopls was working via omnifunc but deoplete-go was still using gocode

Configuration (MUST fill this out):

• vim-go version: origin/master@cf0b9c9

• vimrc you used to reproduce (use a minimal vimrc with other plugins disabled; do not link to a 2,000 line vimrc):

Plug 'fatih/vim-go', { 'do': ':GoUpdateBinaries', 'for': 'go' }
Plug 'shougo/deoplete.nvim', { 'do': ':UpdateRemotePlugins' }
Plug 'zchee/deoplete-go', { 'do': 'make' }

let g:go_def_mode = "gopls"

• Vim version (first three lines from :version): NVIM v0.3.4
• Go version (go version): go version go1.12 darwin/amd64

[dnwe]

p.s. thank you _so_ much for the hard work of implementing gopls support. It is sooo good

[dnwe]

So I _thought_ I had fixed this by adding these config options:

    let g:deoplete#sources#go = ['vim-go']
    let g:deoplete#sources#go#gocode_binary = '/dev/null'

But after experimenting with adding go_debug for 'lsp' I still don't believe deoplete is using gopls via vim-go

Could we add a small note in the :help vim-go-plugins section to mention a recommended configuration for using this via deoplete?

[bhcleek]

This isn't an issue for vim-go. An issue on deoplete asking them how to configure deoplete for Go would be appropriate. vim-go sets up an omnifunc that uses gopls.

[velovix]

I've opened an issue on Deoplete for this.

[velovix]

As per the issue on deoplete, you need to set an Omni pattern, which tells deoplete when to call the omnifunc:

call deoplete#custom#option('omni_patterns', {
\ 'go': '[^. *\t]\.\w*',
\})

@bhcleek Is this something worth adding to the vim-go documentation? I know that deoplete isn't a necessary part of the vim-go experience but the docs do have a section on real-time completion that mentions deoplete and deoplete-go:

* Real-time completion (Neovim and Vim 8):
  https://github.com/Shougo/deoplete.nvim and
  https://github.com/zchee/deoplete-go

Perhaps we could add a blurb there? I'd be happy to submit a pull request.

[bhcleek]

@velovix a PR would be welcome. Thank you!