Emacs as C++ IDE

• Build and install RTags using the RTags Quickstart Guide. Alternatively install RTags using your distribution's package manager.
• Install rtags from MELPA and add the following to your emacs init file:

(require 'rtags)
(require 'company-rtags)

(setq rtags-completions-enabled t)
(eval-after-load 'company
  '(add-to-list
    'company-backends 'company-rtags))
(setq rtags-autostart-diagnostics t)
(rtags-enable-standard-keybindings)

To enable Helm integration add:

(require 'rtags-helm)
(setq rtags-use-helm t)

Before using RTags you need to start rdm and index your project. In order to index your project, RTags requires you to export your project's compile commands with cmake.

$ rdm &
$ cd /path/to/project/root
$ cmake . -DCMAKE_EXPORT_COMPILE_COMMANDS=1
$ rc -J .

We'll see how to automate this process with cmake-ide below.

• C-M-f runs forward-sexp, move forward over a balanced expression that can be a pair or a symbol.
• C-M-b runs backward-sexp, move backward over a balanced expression that can be a pair or a symbol.
• C-M-k runs kill-sexp, kill balanced expression forward that can be a pair or a symbol.
• C-M-<SPC> or C-M-@ runs mark-sexp, put mark after following expression that can be a pair or a symbol.
• C-M-a runs beginning-of-defun, which moves point to beginning of a function.
• C-M-e runs end-of-defun, which moves point to end of a function.
• C-M-h runs mark-defun, which put a region around whole current or following function.

• C-c-r . runs rtags-find-symbol-at-point, which jumps to the definition of the symbol under the cursor.

• C-c-r . runs rtags-find-references-at-point, which lists all references to the symbol under the cursor.
• C-c-r < runs rtags-find-references, which prompts for the symbol name and finds all references.
• C-c-r > runs rtags-find-symbol, which prompts for symbol name and finds all references.

• C-c r ; runs rtags-find-file, which prompts for file name to search for out of currently indexed files.

Alternatively, this can be better accomplished with Projectile.

• C-c r [ rtags-location-stack-back Jumps to last visited tag.
• C-c r ] rtags-location-stack-forward Moves forward in location stack.

• Install irony-mode from MELPA and add the following to your emacs init file:

(add-hook 'c++-mode-hook 'irony-mode)
(add-hook 'c-mode-hook 'irony-mode)
(add-hook 'objc-mode-hook 'irony-mode)

(defun my-irony-mode-hook ()
  (define-key irony-mode-map [remap completion-at-point]
    'irony-completion-at-point-async)
  (define-key irony-mode-map [remap complete-symbol]
    'irony-completion-at-point-async))

(add-hook 'irony-mode-hook 'my-irony-mode-hook)
(add-hook 'irony-mode-hook 'irony-cdb-autosetup-compile-options)

NOTE: Like RTags, Irony requires a compilation database. To create one run the following:

$ cd /path/to/project/root
$ cmake . -DCMAKE_EXPORT_COMPILE_COMMANDS=1

The first time you run irony you must install the irony-server by runing the command: M-x irony-install-server

To use company-mode with Irony:

• Install company-irony from melpa and add the following to your emacs init file:

(add-hook 'irony-mode-hook 'company-irony-setup-begin-commands)
(setq company-backends (delete 'company-semantic company-backends))
(eval-after-load 'company
  '(add-to-list
    'company-backends 'company-irony))

If you want to enable tab-completion with no delay use the following:

(setq company-idle-delay 0)
(define-key c-mode-map [(tab)] 'company-complete)
(define-key c++-mode-map [(tab)] 'company-complete)

To add support for completing C++ headers:

• Install company-irony-c-headers from MELPA
• Remove the following to your emacs init file:

(eval-after-load 'company
  '(add-to-list
    'company-backends 'company-irony))

• Add the following to your emacs init file:

(require 'company-irony-c-headers)
(eval-after-load 'company
  '(add-to-list
    'company-backends '(company-irony-c-headers company-irony)))

• Install flycheck from MELPA and add the following to your emacs init file:

(add-hook 'c++-mode-hook 'flycheck-mode)
(add-hook 'c-mode-hook 'flycheck-mode)

To enable RTags and flycheck integration add the following to your emacs init file:

(require 'flycheck-rtags)

(defun my-flycheck-rtags-setup ()
  (flycheck-select-checker 'rtags)
  (setq-local flycheck-highlighting-mode nil) ;; RTags creates more accurate overlays.
  (setq-local flycheck-check-syntax-automatically nil))
;; c-mode-common-hook is also called by c++-mode
(add-hook 'c-mode-common-hook #'my-flycheck-rtags-setup)

• Install flycheck-irony from MELPA and add the following to your emacs init file:

(eval-after-load 'flycheck
  '(add-hook 'flycheck-mode-hook #'flycheck-irony-setup))

• Install cmake-ide from MELPA and add the following to your emacs init file:

(cmake-ide-setup)

To have cmake-ide automatically create a compilation commands file in your project root create a .dir-locals.el containing the following:

((nil . ((cmake-ide-build-dir . "<PATH_TO_PROJECT_BUILD_DIRECTORY>"))))

You can now build your project using M-x cmake-ide-compile. Additionally, cmake-ide will automatically update your RTags index as well.