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Genki Sugimoto edited this page Jul 23, 2019 · 118 revisions

gopls (pronounced: "go please") is an implementation of the Language Server Protocol (LSP) server for Go. The LSP allows any text editor to be extended with IDE-like features (see https://langserver.org/ for details). It is currently in alpha, so it is not stable.

To install: go get golang.org/x/tools/gopls@latest.

For folks with questions about integrating gopls within an editor, see https://github.com/golang/go/wiki/gopls-integrator-FAQ.

For more information on latest developments and other Go tools: https://github.com/golang/go/wiki/golang-tools.

Table of Contents

Status
Troubleshooting
Known Issues
Installation
Supported Features
Contributing
FAQ
Additional Information

Status

gopls is currently under active development by the Go team. The code is in the x/tools repository, in golang.org/x/tools/internal/lsp and golang.org/x/tools/cmd/gopls. Because we are actively working on gopls, it is not stable. If you choose to use it, be aware that things may regularly break or change. For more gopls discussion, join the #gopls channel in the Gopher Slack.

Troubleshooting

If you see a gopls error or crash, or gopls just stops working, please capture your gopls log and file an issue on the Go issue tracker. Please attach the log and any other relevant information, or if you have one, a case that reproduces the issue. For VSCode users, the gopls log can be found by going to "View: Debug Console" -> "Output" -> "Tasks" -> "gopls".

To increase the level of detail in your logs, start gopls with the -rpc.trace flag. To start a debug server that will allow you to see profiles and memory usage, start gopls with serve --debug=localhost:6060. See the editor configurations section below for information on how to pass these flags via your editor.

If possible, it is helpful to mention an estimated timestamp for when the problem first occurred, or an approximate timestamp for when you reproduced the problem. It is also helpful to see your gopls editor configurations, such as a VSCode settings.json file.

You can then try to restart your gopls instance by restarting your editor, which, in most cases, should correct the problem. In VSCode, the easiest way to restart the language server is by opening the command palette (Ctrl + Shift + P) and selecting "Go: Restart Language Server".

Feel free to ask questions about gopls on the #gopls Gopher Slack channel.

Known Issues

  • Cursor resets to the beginning or end of file on format: #31937.
  • Editing multiple modules in one editor window: #32394.
  • Language features do not work with cgo: #32898.
  • Does not work with build tags: #29202.
  • Find references and rename only work in a single package: #32869, #32877.
  • Completion does not work well after go or defer statements: #29313.

Installation

First, install gopls by running go get golang.org/x/tools/gopls@latest.

At the moment, we suggest using VSCode.

Integration with your text editor

VSCode

Use the VSCode-Go plugin, with the following configuration:

"go.useLanguageServer": true,
"[go]": {
    "editor.snippetSuggestions": "none",
    "editor.formatOnSave": true,
    "editor.codeActionsOnSave": {
        "source.organizeImports": true
    }
},
"gopls": {
    "usePlaceholders": true // add parameter placeholders when completing a function
},
"files.eol": "\n", // formatting only supports LF line endings

VSCode will complain about the "gopls" settings, but they will still work. Once we have a consistent set of settings, we will make the changes in the VSCode plugin necessary to remove the errors.

If you encounter problems with import organization, please try setting a higher code action timeout (any value greater than 750ms), for example:

"[go]": {
  "editor.codeActionsOnSaveTimeout": 3000
}

To enable more detailed debug information, add the following to your VSCode settings:

"go.languageServerFlags": [
    "-rpc.trace", // for more detailed debug logging
    "serve",
    "--debug=localhost:6060", // to investigate memory usage, see profiles 
],

You can disable features through the "go.languageServerExperimentalFeatures" section of the config. An example of a feature you may want to disable is "documentLink", which opens Godoc links when you click on import statements in your file.

Vim / Neovim

Use vim-go ver 1.20+, with the following configuration:

let g:go_def_mode='gopls'
let g:go_info_mode='gopls'

or

Use LanguageClient-neovim, with the following configuration:

" Launch gopls when Go files are in use
let g:LanguageClient_serverCommands = {
       \ 'go': ['gopls']
       \ }
" Run gofmt on save
autocmd BufWritePre *.go :call LanguageClient#textDocument_formatting_sync()

or

Use ale:

let g:ale_linters = {
	\ 'go': ['gopls'],
	\}

see this issue

or

Use vim-lsp, with the following configuration:

augroup LspGo
  au!
  autocmd User lsp_setup call lsp#register_server({
      \ 'name': 'go-lang',
      \ 'cmd': {server_info->['gopls']},
      \ 'whitelist': ['go'],
      \ })
  autocmd FileType go setlocal omnifunc=lsp#complete
  "autocmd FileType go nmap <buffer> gd <plug>(lsp-definition)
  "autocmd FileType go nmap <buffer> ,n <plug>(lsp-next-error)
  "autocmd FileType go nmap <buffer> ,p <plug>(lsp-previous-error)
augroup END

or

Use coc.nvim, with the following coc-settings.json configuration:

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

The editor.action.organizeImport code action will auto-format code and add missing imports. To run this automatically on save, add the following line to your init.vim:

autocmd BufWritePre *.go :call CocAction('runCommand', 'editor.action.organizeImport')

Vim (classic only)

Use the experimental govim, simply follow the install steps.

Emacs

Use lsp-mode. gopls is built in now as a client, so no special config is necessary. You first must install gopls and put it somewhere in your PATH. Here is an example (assuming you are using use-package) to get you started:

(use-package lsp-mode
  :commands (lsp lsp-deferred))

(add-hook 'go-mode-hook #'lsp-deferred)

;; optional - provides fancier overlays
(use-package lsp-ui
  :commands lsp-ui-mode)

;; if you use company-mode for completion (otherwise, complete-at-point works out of the box):
(use-package company-lsp
  :commands company-lsp)

Common errors:

  • When prompted by Emacs for your project folder, if you are using modules you must select the module's root folder (i.e. the directory with the "go.mod"). If you are using GOPATH, select your $GOPATH as your folder.
  • Emacs must have your environment set properly (PATH, GOPATH, etc). You can run M-x getenv <RET> PATH <RET> to see if your PATH is set in Emacs. If not, you can try starting Emacs from your terminal, using this package, or moving your shell config from .bashrc into .bashenv (or .zshenv).
  • Make sure lsp-mode, lsp-ui and company-lsp are up-to-date, and make sure lsp-go is not installed.

To troubleshoot, look in the *lsp-log* buffer for errors.

Acme

Use the experimental acme-lsp, simply follow the install steps.

Sublime Text

Use the LSP package. After installing it using Package Control, do the following:

  • Open the Command Palette
  • Find and run the command LSP: Enable Language Server Globally
  • Select the gopls item. Be careful not to select the similarly named golsp by mistake.

Finally, you should familiarise yourself with the LSP package's Settings and Key Bindings. Find them under the menu item Preferences > Package Settings > LSP.

Supported Features

  • Autocompletion
  • Jump to definition
  • Signature help
  • Hover
  • Document symbols
  • References
  • Rename

Contributing

Contributions are welcome, but since development is so active, we request that you file an issue and claim it before starting to work on something. Otherwise, it is likely that we might already be working on a fix for your issue.

Please see all available issues under the gopls label on the Go issue tracker. Any issue without an assignee and with the label "Suggested" is fair game - just assign yourself or comment on the issue before you begin working!

FAQ

  • Why is it called gopls? Since gopls works both as a language server and as a command line tool, we wanted a name that could be used as a verb. For example, gopls check should read as "go please check." See: golang.org/cl/158197.

Additional Information

Questions can be directed toward @stamblerre or @ianthehat. For consistent updates on the development progress of gopls, see the notes from the golang-tools meetings (https://github.com/golang/go/wiki/golang-tools).

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