doomemacs/modules/completion/company/README.org

completion/company

• Description
  • Module Flags
  • Plugins
• Prerequisites
• Features
  • Code completion
  • Vim-esque omni-completion prefix (C-x)
• Configuration
  • Enable as-you-type code completion
  • Enable company backend(s) in certain modes
• Troubleshooting
  • Code-completion doesn't pop up automatically.
  • X-mode doesn't have code completion support or requires extra setup.
  • No backends (or the incorrect ones) have been registered for X-mode.

Description

This module provides code completion, powered by company-mode. It is required for code completion in many of Doom's :lang modules.

https://assets.doomemacs.org/completion/company/overlay.png

Module Flags

• +auto Enables as-you-type completion.
• +childframe Enables displaying completion candidates in a child frame, rather than an overlay or tooltip (among with other UI enhancements). This requires GUI Emacs 26.1+.

Plugins

• company-mode
• company-dict
• company-prescient
• company-box

Prerequisites

This module has no direct prerequisites.

However, some major modes may require additional setup for code completion to work in them. Some major modes may have no completion support at all. Check that major mode's module's documentation for details.

Features

Code completion

Ccompletion must be triggered manually with the C-SPC key. If you want as-you-type code completion, the +auto module flag will enable it.

Keybind	Description
C-SPC	Invoke code completion manually
C-n	Go to next candidate
C-p	Go to previous candidate
C-j	(evil) Go to next candidate
C-k	(evil) Go to previous candidate
C-h	Display documentation (if available)
C-u	Move to previous page of candidates
C-d	Move to next page of candidates
C-s	Filter candidates
C-S-s	Search candidates with helm/ivy
C-SPC	Complete common
TAB	Complete common or select next candidate
S-TAB	Select previous candidate

Vim-esque omni-completion prefix (C-x)

In the spirit of Vim's omni-completion, the following insert mode keybinds are available to evil users to access specific company backends:

Keybind	Description
C-x C-]	Complete etags
C-x C-f	Complete file path
C-x C-k	Complete from dictionary/keyword
C-x C-l	Complete full line
C-x C-o	Invoke complete-at-point function
C-x C-n	Complete next symbol at point
C-x C-p	Complete previous symbol at point
C-x C-s	Complete snippet
C-x s	Complete spelling suggestions

Configuration

Enable as-you-type code completion

The +auto module flag enables this. You may customize company-idle-delay to control how quickly the popup should appear.

The +company/toggle-auto-completion command is also available to toggle this interactively.

Enable company backend(s) in certain modes

The set-company-backend! function exists for setting company-backends buffer-locally in MODES, which is either a major-mode symbol, a minor-mode symbol, or a list of either. BACKENDS are prepended to company-backends for those modes.

(after! js2-mode
  (set-company-backend! 'js2-mode 'company-tide 'company-yasnippet))

(after! sh-script
  (set-company-backend! 'sh-mode
    '(company-shell :with company-yasnippet)))

(after! cc-mode
  (set-company-backend! 'c-mode
    '(:separate company-irony-c-headers company-irony)))

To unset the backends for a particular mode, pass nil to it:

(after! sh-script
  (set-company-backend! 'sh-mode nil))

Troubleshooting

If code completion isn't working for you, consider the following common causes before you file a bug report:

Code-completion doesn't pop up automatically.

This is by design. The expectation is that you invoke completion manually with C-SPC. This was decided because code-completion backends can be slow, some dreadfully so, and invoking them every time you move your cursor can add pauses and delays while editing.

If, despite that, you still want this functionality, use the +auto flag to enable it.

X-mode doesn't have code completion support or requires extra setup.

There is no guarantee your language mode will have completion support.

Some, like lua-mode, don't have completion support in Emacs at all. Others may requires additional setup to get code completion working. For instance, go-mode requires guru to be installed on your system, and enh-ruby-mode requires that you have a Robe server running (M-x robe-start).

Check the relevant module's documentation for this kind of information.

No backends (or the incorrect ones) have been registered for X-mode.

Doom expects every mode to have an explicit list of company-backends (and as short a list as possible). This may mean you aren't getting all the completion you want or any at all.

Check the value of company-backends (SPC h v company-backends) from that mode to see what backends are available. Check the Configuration section for details on changing what backends are available for that mode.