Irony-Mode

A C/C++ minor mode powered by libclang

irony-mode is an Emacs minor-mode that aims at improving the editing experience for the C, C++ and Objective-C languages. It works by using a combination of an Emacs package and a C++ program (irony-server) that uses libclang.

Features:

Code completion:
- With Emacs' built-in completion-at-point-functions
- With company-mode's backend: company-irony
- With auto-complete' source: ac-irony

Dependencies

Elisp dependencies

These dependencies will be installed automatically when using the standard installation procedure described below.

Package	Comment
cl-lib	Built-in since Emacs 24.3
YASnippet	Optional. Used only when available to provide snippets expansion of completion arguments

Irony-Server prerequisites

irony-server provides the libclang interface to irony-mode. It uses a simple protocol based on S-expression. This server, written in C++ and requires the following packages to be installed on your system:

CMake >= 2.8.3
libclang

Installation

The recommended way to install irony-mode and its dependencies is to use a package manager.

Using MELPA

  M-x package-install RET irony-mode RET

Using el-get

  M-x el-get-install RET irony-mode RET

Configuration

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

;; replace the `completion-at-point' and `complete-symbol' bindings in
;; irony-mode's buffers by irony-mode's function
(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)

Usage

On the first run, irony-mode will ask you to build and install irony-server. To do so, type M-x irony-install-server RET.

To tune irony-mode, use customize:

M-x customize-group RET irony RET

In order to provide context sensitive and accurate information, irony-mode needs to know about the compiler flags used to parse the current buffer. The best way to achieve this is to use a Compilation Database.

Compilation Database

In order to work correctly, irony-mode needs to know the compile flags. irony-cdb aims to provide as automatic as possible compile flags discovery, with minimal user input.

Type M-x irony-cdb-menu RET to display the build configuration menu.

The menu should be self explanatory, it will let you chose amongst a list of compilation databases. It works great with the following ones:

.clang_complete - A file at the root of your project containing the compilation flags, one per line. This is compatible with the with plugin Rip-Rip/clang_complete. If you want to generate the .clang_complete automatically, take a look there: cc_args.py documentation.

FAQ

It's slow, why?

A bug in old version of Clang (at least '3.1-8') caused the completion to fail on the standard library types. To eliminate this bug an optimisation has been disabled in the parsing of a translation unit. This result in a slower parsing.

This only affect old versions of Clang (< 3.2), it is suggested to update your libclang installation if you want to take advantage of the optimizations.

libclang.so: cannot open shared object file...

Compiling irony-server succeed but you have the following message when you try to run the irony-server executable:

'irony-server: error while loading shared libraries: libclang.so: cannot open shared object file: No such file or directory

Maybe it's due to a non-standard location for your installation of libclang. A path such as /usr/local/lib might not be in the path list of the dynamic loader (see ld.so.conf).

To solve this issue you can try to build irony-server with the following command:

cmake -DUSE_RPATH=ON ..

tomekwier/irony-mode