x/tools/gopls: add tests for cgo

[Kraust]

What version of Go are you using (go version)?

❯ go version
go version go1.12.4 linux/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

❯ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home3/rdupuis/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/rdupuis/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build200403948=/tmp/go-build -gno-record-gcc-switches"

What did you do?

See minimal working example in the following repository
https://github.com/Kraust/cgo_gopls
Tested with latest coc.nvim and latest gopls from official repo.
Not listed in the repository is my coc.nvim settings. I do not believe this is a coc.nvim issue but I will post an issue on their tracker if needed:

"coc
inoremap <silent><expr> <TAB>
      \ pumvisible() ? coc#_select_confirm() :
      \ coc#expandableOrJumpable() ? coc#rpc#request('doKeymap', ['snippets-expand-jump','']) :
      \ <SID>check_back_space() ? "\<TAB>" :
      \ coc#refresh()

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

let g:coc_snippet_next = '<Tab>'
let g:coc_snippet_prev = '<S-Tab>'

What did you expect to see?

coc.nvim with successful tab-compeltion (autocomplete)

What did you see instead?

coc.nvim's tab completion only works if import "C" is commented out.

Also CocInfo reports the following:

## versions

vim version: NVIM v0.4.0-571-g21b108f
node version: v11.9.0
coc.nvim version: 0.0.65-303d95d2bb
term: xterm-256color
platform: linux

## Error messages

## Output channel: snippets

## Output channel: languageserver.golang
2019/04/18 20:09:19 get package failed: no metadata found for /home/rdupuis/go/src/github.com/kraust/cgo_gopls/cgo_gopls.go
2019/04/18 20:09:19 get token failed: no metadata found for /home/rdupuis/go/src/github.com/kraust/cgo_gopls/cgo_gopls.go
2019/04/18 20:09:20 get token failed: no metadata found for /home/rdupuis/go/src/github.com/kraust/cgo_gopls/cgo_gopls.go

[wwcd]

Using pkg.GoFiles replace pkg.CompiledGoFiles? as CGO files is processed before compile.

It test work well.

https://github.com/golang/tools/blob/550556f78a900afacb9e8b22219f5e5b5c6106db/internal/lsp/cache/check.go#L151

[oakad]

I can confirm that this happens with vscode-go as well. Given a file with any sort of cgo header:

package pack

/*
#include "some.h"
// more C
*/
import "C"

// Go code follows

gopls always returns "no file information" error:

[Error - 1:51:15 pm] Request textDocument/codeAction failed.
Message: no file information for file: file-with-cgo-header.go
Code: 0

And, of course, no code editing assist features are working in such files.

Other files in the very same package/project work just fine.

[joegrasse]

@stamblerre is there a downside to the workaround that @wwcd suggests above?

[stamblerre]

Sorry for my delayed response on this issue. We are still trying to figure out the right way to handle cgo. Unfortunately, @wwcd's suggestion won't work for us. We have to use CompiledGoFiles because those are the actual files we need to build a package.

We probably won't have a meaningful solution for autocompletion and other language features in cgo files, but as a start @ianthehat and I have discussed simply disabling diagnostics for all generated files.

[joegrasse]

We probably won't have a meaningful solution for autocompletion and other language features in cgo files, but as a start @ianthehat and I have discussed simply disabling diagnostics for all generated files.

@stamblerre In this case, would I still get autocompletion of Go stuff just not C stuff in a file with C and Go? If so, I would be OK with that.

[joegrasse]

@stamblerre Just curious on an answer to the above question.

[wubo0067]

the https://github.com/cri-o/cri-o.git use cgo, Causes Gopls not to work, no prompts

[gopherbot]

Change https://golang.org/cl/181546 mentions this issue: internal/lsp: stop requiring a .go extension for all Go files

[ericm]

I have the same issue with gopls and cgo using coc.nvim.

[coc.nvim] Error output from languageserver.golang: 
unable to check package for file:///home/eric/forks/goncurses/defs.go: 
loadParseTypecheck: no metadata found for /home/eric/forks/goncurses/defs.go[coc.nvim] 
Error output from languageserver.golang: no package available for file:///home/eric/forks/goncurses/defs.go