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) exposing libclang.
These dependencies will be installed automatically when using the standard installation procedure described below.
|cl-lib||Built-in since Emacs 24.3|
|json||Built-in since Emacs 23.1|
|YASnippet||Optional. May be used to provide post-completion expansion of function arguments|
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:
The recommended way to install
irony-mode and its dependencies is to use a package manager.
M-x package-install RET irony RET
apton Debian ≥10 and derivatives
sudo apt install elpa-irony
Accessing a newer Clang and LLVM Toolchain on Debian and derivatives
The backports mechanism is the recommended and officially supported method of accessing newer versions than
Debian stable provides.
sudo apt install -t $release_name-backports elpa-irony
If the llvm-toolchain backport is not new enough please use the following repository: LLVM Debian/Ubuntu nightly packages. This repository is maintained by Sylvestre Ledru, who is responsible for the official Debian package. His repository also supports Ubuntu and derivatives. When using this unofficial repository the MELPA package of irony-mode should be used in preference to the
(add-hook 'c++-mode-hook 'irony-mode) (add-hook 'c-mode-hook 'irony-mode) (add-hook 'objc-mode-hook 'irony-mode) (add-hook 'irony-mode-hook 'irony-cdb-autosetup-compile-options)
irony-mode should work fine on Windows but there are some things to take care of first.
libclang.dllis expected to be available in the
PATHor in Emacs'
Emacs >= 24.4 is required. A bug in previous versions makes irony unuseable (Emacs bug #18420).
w32-pipe-read-delaydefault value of
50should be changed. This should not cause any issue on today's version of Windows. The default value of
50may be lowered in mainline Emacs in future versions, until then, I suggest to set it to
w32-pipe-buffer-size, introduced by Emacs 25, can be set to a larger value than the default to improve
irony-servercommunication performances (c.f. https://github.com/Sarcasm/irony-mode/issues/321). The variable to customize is
Windows configuration tweaks to add to your Emacs configuration:
;; Windows performance tweaks ;; (when (boundp 'w32-pipe-read-delay) (setq w32-pipe-read-delay 0)) ;; Set the buffer size to 64K on Windows (from the original 4K) (when (boundp 'w32-pipe-buffer-size) (setq irony-server-w32-pipe-buffer-size (* 64 1024)))
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.
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.
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.
Please refer to
irony-cdb supports the following compilation databases:
JSON Compilation Database - A JSON formatted file generated by various build tools. The file is named
compile_commands.json, it lists the compile options associated to each file in the project.
CMake >= 2.8.5 will generate a compilation database in the build directory when issuing the following command
cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON <...>.
ninja >= 1.2 will generate a JSON Compilation Database when using the
Bear generates a JSON Compilation Database file by "monitoring" the build of a project. The typical usage for a
make-based project will be
bear -- make -B.
.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_completeautomatically, take a look at the cc_args.py documentation.
More detailed information on compilation database is available here:
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...
irony-server succeed but you have the following message when you try to run the
'irony-server: error while loading shared libraries: libclang.so: cannot open shared object file: No such file or directory
libclang is installed in a non-standard location (one that is missing from the path list of the dynamic loader, see ld.so.conf) you can tell CMake to use the rpath when installing the target
irony-server. To enable rpath in CMake use the following command:
cmake -DCMAKE_INSTALL_RPATH_USE_LINK_PATH=ON <args...>
If you're running OS X, you can also use
install_name_tool to explicitly tell
irony-server where an appropriate version of
libclang.dylib lives. For example, Homebrew (with
brew install llvm --with-clang) will install a
libclang.dylib library at
/usr/local/opt/llvm/lib/libclang.dylib; you can instruct
irony-server to use this with something like:
install_name_tool -change @rpath/libclang.dylib /usr/local/opt/llvm/lib/libclang.dylib irony-server