This is a guide to installing RTags on linux, and then using it in spacemacs

The distro I use in this post is Ubuntu 16.04, but most of the information should be general in nature.

We will install RTags’ dependencies, build and install RTags itself, build an RTags tag database for our project, and then enable the rtags layer in spacemacs.


According to the Installing rtags section of the Readme, we need to have the following dependencies (starred ones are optional):

  • clang-3.3 or higher
  • cmake-2.8 or higher
  • pkg-config*
  • bash-completion*
  • lua*

I am using Ubuntu 16.04, so the default versions offered by the Ubuntu package manager are all sufficient

sudo apt install clang libclang-dev cmake pkg-config bash-completion lua

Download, build and install RTags

cd /tmp
git clone --recursive git@github.com:Andersbakken/rtags.git
cd rtags
mkdir build && cd build
cmake ..
make -j8
sudo make install

Configure a service in systemd

Create a systemd config directory for your user

mkdir -p ~/.config/systemd/user

Create the RTags daemon socket service config

$ vim ~/.config/systemd/user/rdm.socket

Add the following:

Description=RTags daemon socket



Create the RTags daemon service config

$ vim ~/.config/systemd/user/rdm.service

Add the following

Description=RTags daemon


ExecStart=/usr/local/bin/rdm --log-file=%h/.rtags/rdm.log --data-dir=%h/.rtags/rtags-cache --verbose --inactivity-timeout 300

Enable and start the socket service

systemctl --user enable rdm.socket
systemctl --user start rdm.socket

Build an RTags database for your project

Since RTags uses clang to parse your code, it needs to know the compiler flags your project uses.

There are multiple ways to tell RTags what flags you use.

My project uses cmake, so I will use that.

Using cmake we can generate a compile_commands.json file which RTags will use to index the project

cd ~/src/project
mkdir build && cd build

Now we can instruct RTags to index our code

rc -J ./compile_commands.json

This takes a while to complete, we can watch the progress by looking at the log file we configured in ~/.config/systemd/user/rdm.service

tail -f ~/.rtags/rdm.log

Enable RTags in spacemacs

We now need to set up RTags support in emacs, and configure some keybindings.

For this I’m using mineo-rtags

I copied the 2 files packages.el and keybindings.el into a folder in my spacemacs config directory

mkdir ~/.spacemacs.d/mineo-rtags && cd ~/.spacemacs.d/mineo-rtags
wget https://raw.githubusercontent.com/mineo/dotfiles/master/spacemacs/.emacs.d/private/layers/mineo-rtags/packages.el
wget https://raw.githubusercontent.com/mineo/dotfiles/master/spacemacs/.emacs.d/private/layers/mineo-rtags/keybindings.el

For posterity, here is the contents of these two files at the time of writing:


(defconst mineo-rtags-packages

(defun mineo-rtags/init-cmake-ide ()
  (use-package cmake-ide

(defun mineo-rtags/init-rtags ()
  (use-package rtags
    (setq rtags-autostart-diagnostics t
          rtags-completions-enabled t
          rtags-use-helm t)
    (push '(company-rtags)
    (add-hook 'c-mode-common-hook 'rtags-start-process-unless-running))
  (use-package flycheck-rtags
    :ensure rtags))


(defconst mineo-rtags-overrides
  '(("C-]" 'rtags-find-symbol-at-point)
    ("M-." 'rtags-find-symbol-at-point)))

(defun mineo-rtags-set-evil-keys ()
  (dolist (override mineo-rtags-overrides)
    (evil-local-set-key 'normal (car override) (cdr override))))

(add-hook 'c-mode-common-hook 'mineo-rtags-set-evil-keys)

;;; https://github.com/mheathr/spacemacs/blob/develop/contrib/!lang/c-c%2B%2B/packages.el

(dolist (mode '(c-mode c++-mode))
  (evil-leader/set-key-for-mode mode
    "g ." 'rtags-find-symbol-at-point
    "g ," 'rtags-find-references-at-point
    "g v" 'rtags-find-virtuals-at-point
    "g V" 'rtags-print-enum-value-at-point
    "g /" 'rtags-find-all-references-at-point
    "g Y" 'rtags-cycle-overlays-on-screen
    "g >" 'rtags-find-symbol
    "g <" 'rtags-find-references
    "g [" 'rtags-location-stack-back
    "g ]" 'rtags-location-stack-forward
    "g D" 'rtags-diagnostics
    "g G" 'rtags-guess-function-at-point
    "g p" 'rtags-set-current-project
    "g P" 'rtags-print-dependencies
    "g e" 'rtags-reparse-file
    "g E" 'rtags-preprocess-file
    "g R" 'rtags-rename-symbol
    "g M" 'rtags-symbol-info
    "g S" 'rtags-display-summary
    "g O" 'rtags-goto-offset
    "g ;" 'rtags-find-file
    "g F" 'rtags-fixit
    "g L" 'rtags-copy-and-print-current-location
    "g X" 'rtags-fix-fixit-at-point
    "g B" 'rtags-show-rtags-buffer
    "g I" 'rtags-imenu
    "g T" 'rtags-taglist
    "g h" 'rtags-print-class-hierarchy
    "g a" 'rtags-print-source-arguments))

(provide 'keybindings)

Enable mineo-rtags layer in spacemacs

    c-c++-enable-clang-support t

Restart spacemacs and it should install rtags and its dependencies.

The keybindings are available under , g

Written on August 26, 2016