x/tools/internal/lsp: support files outside $GOPATH and outside of a module

[Lekensteyn]

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

$ go version
go version go1.12.1 linux/amd64

Originally encountered with 1.12. Reproduced on Arch Linux (x86_64).

What did you do?

Install vim-go (fatih/vim-go@17d4c08) for use with vim (8.1.1073-1). This will use gopls by default for autocompletion.

Create a file outside $GOPATH, e.g. /tmp/foo.vim with this sample content:

package main

import "fmt"

func main() {
	fmt.Println("vim-go")
	fmt.
}

After fmt., press Ctrl-X, Ctrl-O to trigger auto completion.

Alternatively, try this reproducer which does not require vim:

repro.py

#!/usr/bin/env python3
import json
import os
import subprocess
import sys

uri = os.path.expanduser('~/go/src/github.com/google/fscrypt/cmd/fscrypt/foo.go')
# does not work
uri = '/tmp/foo.go'
if len(sys.argv) >= 2:
    uri = sys.argv[1]

# rootUri value does not seem to matter
rootUri = "file:///"
uri = "file://%s" % uri

cmd_a = {
  "method": "initialize",
  "jsonrpc": "2.0",
  "id": 1,
  "params": {
    "rootUri": rootUri,
    "capabilities": {
      "workspace": {},
      "textDocument": {}
    },
    "processId": 13448
  }
}

cmd_b = {
  "method": "textDocument/didChange",
  "jsonrpc": "2.0",
  "params": {
    "contentChanges": [
      {
        "text": "package main\n\nimport \"fmt\"\n\nfunc main() {\n\tfmt.Println(\"vim-go\")\n\tfmt.\n}\n"
      }
    ],
    "textDocument": {
      "uri": uri
    }
  }
}

cmd_c = {
  "method": "textDocument/completion",
  "jsonrpc": "2.0",
  "id": 2,
  "params": {
    "textDocument": {
      "uri": uri
    },
    "position": {
      "character": 5,
      "line": 6
    }
  }
}

def send_receive(proc, cmd, receive=False):
    print('\n# Sending: %r\n' % cmd)
    s = json.dumps(cmd)
    proc.stdin.write('Content-Length: %d\r\n\r\n%s' % (len(s), s))
    proc.stdin.flush()
    # Read response
    if receive:
        size = int(proc.stdout.readline().split('Content-Length: ')[1])
        print('\n# Response (%d bytes)' % size)
        while proc.stdout.readline().strip():
            pass
        print(json.dumps(json.loads(proc.stdout.read(size)), indent=4))

with subprocess.Popen(os.path.expanduser('~/go/bin/gopls'),
        stdin=subprocess.PIPE, stdout=subprocess.PIPE, encoding='utf8') as p:
    send_receive(p, cmd_a, receive=True)
    send_receive(p, cmd_b)
    send_receive(p, cmd_c, receive=True)
    p.terminate()
    print('')

Run python3 repro.py which will send some commands to gopls and print the responses.

What did you expect to see?

Expected to see completion:

With the Python reproducer, I would expect something like:

[Trace - 12:52:45 AM] Received response 'textDocument/completion - (2)' in 1010ms.
Params: {"isIncomplete":false,"items":[{"label":"Errorf(format string, a ...interface{})", ...

What did you see instead?

No autocompletion.

With the Python reproducer, I see:

[Trace - 12:57:34 AM] Sending request 'textDocument/completion - (2)'.
Params: {"textDocument": {"uri": "file:///tmp/foo.go"}, "position": {"character": 5, "line": 6}}

[Error - 12:57:34 AM] send textDocument/completion#2 no file information for file:///tmp/foo.go

Additional information

I posted an analysis at fatih/vim-go#2193 (comment), the following patch would permit gopls to be used with individual files, e.g. for use with go run script.go. When used with projects with multiple files, there may be issues like missing identifiers (unless the client loads all files) or duplicate identifiers when multiple packages are combined.

Regardless of those issues, it does address the single script use case though.

[Patch redacted by @bcmills. Please send a PR or CL so that we can verify CLA compliance.]

Other similar issues:

• x/tools/internal/lsp: handle module paths below root path #29174 - same error message, but unlike this one, that issue occurs within a project below GOPATH. It can be worked around by the editor.

[NamPNQ]

Workaround

mv /tmp/foo.go $GOPATH/src/
ln -s $GOPATH/src/foo.go /tmp/foo.go

[bcmills]

CC @stamblerre @ianthehat

[bcmills]

@Lekensteyn We can't accept patches posted to issues, but if you have a fix please send a PR or CL per https://golang.org/doc/contribute.html.

[stamblerre]

This should work correctly as of https://golang.org/cl/183620. Closing.

[bstaletic]

This isn't resolved. Editing a file outside of $GOPATH still produces the same error with gopls from last night (09. Aug 2019.)

EDIT: Apologies. It works after there's package main in the file.

[relunctance]

• cd YouCompleteMe/third_party/ycmd
• cd third_party/go/src/golang.org/x/tools
• git pull origin master
• cd cmd/gopls
• go build && mv main gopls

Thanks Guy , it can resolve my problem
my env :
Vim version 8.1.1722
Go version go1.11
vimrc :

" YouCompleteMe 
let g:ycm_server_python_interpreter='/usr/local/bin/python3'
" Note that you can install YCM with both libclang and clangd enabled. In that case clangd will be preferred unless you have the following in your vimrc:
"let g:ycm_use_clangd = 0
let g:ycm_global_ycm_extra_conf = "~/.vim/bundle/YouCompleteMe/.ycm_extra_conf.py"
let g:ycm_language_server =
  \ [
  \   {
  \     'name': 'gopls',
  \     'cmdline': [ '~/.vim/bundle/YouCompleteMe/third_party/ycmd/third_party/go/src/golang.org/x/tools/cmd/gopls/gopls' , "-rpc.trace" ],
  \     'filetypes': [ 'go' ],
  \     "project_root_files": [ "go.mod" ]
  \   }
  \ ]

let g:go_def_mode='~/.vim/bundle/YouCompleteMe/third_party/ycmd/third_party/go/src/golang.org/x/tools/cmd/gopls/gopls'
let g:go_info_mode='~/.vim/bundle/YouCompleteMe/third_party/ycmd/third_party/go/src/golang.org/x/tools/cmd/gopls/gopls'
" let g:ycm_log_level = 'debug'
set completeopt=longest,menu

[bstaletic]

@relunctance Don't do that. YCM migrated to gopls a while ago. Just use ./install.py --go-completer - that's why gopls is in third_party.

[relunctance]

@bstaletic Thanks , I have remove ycm_language_server