Generates config files for YouCompleteMe (
Python Shell Vim script


This is a script which generates a list of compiler flags from a project with an arbitrary build system. It can be used to:

It works by building the project with a fake toolchain, which simply and filters compiler flags to be stored in the resulting file.

It is reasonably fast, taking ~10 seconds to generate a configuration file for the Linux kernel.


Add NeoBundle 'rdnetto/YCM-Generator' to your vimrc (or the equivalent for your plugin manager).

For vim-plug users, add Plug 'rdnetto/YCM-Generator', { 'branch': 'stable'} to your vimrc.

Alternatively, Arch Linux users can install YCM-Generator using the (unofficial) AUR package.


Run ./ PROJECT_DIRECTORY, where PROJECT_DIRECTORY is the root directory of your project's build system (i.e. the one containing the root Makefile, etc.)

You can also invoke it from within Vim using the :YcmGenerateConfig or :CCGenerateConfig commands to generate a config file for the current directory. These commands accept the same arguments as ./, but do not require the project directory to be specified (it defaults to the current working directory).

Requirements and Limitations

  • Requirements:

    • Python 2
    • Clang
  • Supported build systems:

    • make
    • cmake
    • qmake
    • autotools

Your build system should support specifying the compiler through the CC/CXX environment variables, or not use an absolute path to the compiler.

Some flags present in the resulting configuration file may be mutually exclusive with each other - reading the generated file prior to use is recommended.

The script assumes that executables with the names clang and clang++ exist in your PATH. This has been known to cause issues under Ubuntu, where the C++ compiler may be called clang++-3.6 (see #50).

Documentation & Support

  • run ./ --help to see the complete list of supported options.
  • if you receive the error message ERROR: No commands were logged to the build logs, try using the --verbose flag to see any error messages
    • some build systems require certain environment variables to be set. Note that these will not be used by YCM-Generator by default, unless --preserve-environment is used
    • if you open an issue regarding this error message, please include the output when running with --verbose and a link to the project repo (if possible)


Patches are welcome. Please submit pull requests against the develop branch.

Windows support

The script is currently supported under Unices (Linux, NixOS[1], BSD, OS X) only. Implementing Windows support consists of porting the contents of fake-toolchain/Unix. If you are interested in implementing/testing this, please open a pull request.

[1] May require --preserve-environment - see #19

Test Cases

The following projects are used for testing:

Project Build system Notes
Linux kernel Kbuild (Make)
Vim-qt Autotools
Clementine Cmake
ExtPlane Qmake Should be tested with both versions of Qt.
OpenFOAM wmake


YCM-Generator is published under the GNU GPLv3.