This is the official Emacs package for Racer.
Table of Contents
racer.el supports code completion of variables, functions and modules.
You can also press F1 to pop up a help buffer for the current completion candidate.
Note that due to a limitation of racer, racer.el cannot offer completion for macros.
racer.el can jump to definition of functions and types.
You can use M-. to go to the definition, and M-, to go back.
racer.el can show a help buffer based on the docstring of the thing at point.
Use M-x racer-describe to open the help buffer.
You will need to use a nightly version of rust. If you're using rustup, run
$ rustup toolchain add nightly
Install Racer and download the source code of Rust:
$ rustup component add rust-src
$ cargo +nightly install racer
Allow Emacs to install packages from MELPA:
(require 'package)
(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/"))
Install the Emacs package for Racer: M-x package-install RET racer RET
Configure Emacs to activate racer when rust-mode starts:
(add-hook 'rust-mode-hook #'racer-mode)
(add-hook 'racer-mode-hook #'eldoc-mode)
For completions, install company with M-x package-install RET company RET
. A sample configuration:
(add-hook 'racer-mode-hook #'company-mode)
(require 'rust-mode)
(define-key rust-mode-map (kbd "TAB") #'company-indent-or-complete-common)
(setq company-tooltip-align-annotations t)
For automatic completions, customize company-idle-delay
and
company-minimum-prefix-length
.
Racer process may be slow to respond for instance when indexing. You can
customize racer-command-timeout
and racer-eldoc-timeout
to avoid rendering
your Emacs session unresponsive. Eldoc timeout should be on the lower side and
defaults to 0.5 seconds. You can probably tweak it down on a fast machine.
Timeout of nil
will wait indefinitely.
To test completion: Open a rust file and try typing use std::io::B
and press TAB.
To test go to definition: Place your cursor over a symbol and press
M-.
to jump to its definition.
Press C-x 4 .
to jump to its definition in another window.
Press C-x 5 .
to jump to its definition in another frame.
Press M-,
to jump back to the previous cursor location.
If it doesn't work, try M-x racer-debug
to see what command was
run and what output was returned.
racer.el includes tests. To run them, you need to install Cask, then:
$ cask install
$ cask exec ert-runner