[REQUEST] Only use format-all-the-code if the language server doesn't support formatting

[rassie]

Describe the feature

The basic idea has been introduced to format-all-the-code in lassik/emacs-format-all-the-code#47. The assumption is that a language server probably has a better idea how to format the code than any default set in format-all-the-code. The proposal, quoted from there, goes like this:

1. If lsp-mode is not enabled for the current buffer, fallback to the current behaviour.
2. Otherwise, check for textDocument/formatting capability of the current language server (or maybe servers, since that's apparently a supported workflow). If it's not available, fallback to current behaviour.
3. Otherwise, use textDocument/formatting (probably via lsp-format-buffer) instead of the predefined tool.

It's not clear whether it's a better idea to make format-all-the-things LSP-aware or extend doom-emacs' auto-formatting wrapper. Either way I'd be happy to have the feature.

System information

- OS: gnu/linux (x86_64-pc-linux-gnu)
- Shell: /bin/bash
- Emacs: 26.2 (Apr 12, 2019)
- Doom: 2.0.9 (HEAD -> develop, _upgrade/develop f754d4ff 2019-07-23 18:23:17 +0200)
- Graphic display: nil (daemon: nil)
- System features: XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS GLIB NOTIFY LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS XWIDGETS LIBSYSTEMD LCMS2
- Details:
  ```elisp
  env bootstrapper: nil
  elc count: 0
  uname -a:  Linux 5.0.0-25-generic #26~18.04.1-Ubuntu SMP Thu Aug 1 13:51:02 UTC 2019 x86_64
  modules:   (:completion company (ivy +fuzzy +childframe) :ui doom doom-dashboard hl-todo modeline nav-flash ophints (popup +all +defaults) treemacs unicode vc-gutter vi-tilde-fringe window-select workspaces :editor fold (format +onsave) multiple-cursors rotate-text snippets :emacs dired vc :tools ansible direnv docker editorconfig eval flycheck (lookup +docsets) lsp magit make pdf rgb terraform :lang data emacs-lisp (go +lsp) (haskell +intero) (java +lsp) (javascript +lsp) (kotlin +lsp) latex markdown (org +attach +babel +capture +export +habit +present +protocol) perl php plantuml (python +lsp) qt rest ruby (sh +fish) (web +lsp) :app write :config default)
  packages:  (full-ack visual-regexp nginx-mode company-qml persistent-scratch gitlab-ci-mode gitlab-ci-mode-flycheck rpm-spec-mode kotlin-mode flycheck-kotlin puppet-mode prettier-js add-node-modules-path solaire-mode comment-dwim-2 ag lsp-python-ms glsl-mode)
  exec-path: (./node_modules/.bin ~/.npm-packages/bin/ ~/.local/bin/ /bin ~/go/bin ~/.npm-packages/bin ~/.cargo/bin/ ~/.npm-packages/bin/ ~/.local/bin/ /bin ~/go/bin /bin ~/bin ~/.local/bin /usr/local/sbin /usr/local/bin /usr/sbin /usr/bin /sbin /bin /usr/games /usr/local/games /snap/bin ~/.dotnet/tools /usr/lib/maven3/bin ~/.fzf/bin /usr/lib/x86_64-linux-gnu/emacs/26.2/x86_64-linux-gnu)

[hlissner]

Sorry for the late response; just chiming in to let you know I am aware of this issue. The :editor format module is painfully overdue a rewrite, both to make it LSP-aware, and possibly to replace format-all-the-code with reformatter.el to facilitate a more customizable formatting backend.

I don't yet have time to work on this, however, but I haven't forgotten about it.

Also, @Kaali in #2516 brought up this LSP-unawareness in go-mode. For the time being, the workaround for this is to disable our formatter by adding go-mode to +format-on-save-enabled-modes (which is a negated list, by default, due to its first element being not), then add lsp-format-buffer to that mode's local before-save-hook. e.g.

(add-to-list '+format-on-save-enabled-modes 'go-mode t)

(add-hook! 'go-mode-hook
  (add-hook 'before-save-hook #'lsp-format-buffer nil 'local)
  (add-hook 'before-save-hook #'lsp-organize-imports nil 'local))

[rassie]

@hlissner Thanks for the feedback! Before you replace format-all-the-code, you might be interested in recent developments, which introduces global and buffer-local configurable formatters. Otherwise: don't mind me, I'll be happy if and when it's done, but I'm also quite happy with Doom right now even without it :)

[hlissner]

As of 7472cff, our format commands support LSP (if the running server supports formatting).

This can be disabled globally with

(setq +format-with-lsp nil)

Or on a per-mode basis with

(setq-hook! 'python-mode-hook +format-with-lsp nil)

In any case I'll consider this resolved. Thanks for bringing it to my attention!