xunused

xunused is a tool to find unused C/C++ functions and methods across source files in the whole project. It is built upon clang to parse the source code (in parallel). It then shows all functions that had a definition but no use. Templates, virtual functions, constructors, functions with static linkage are all taken into account. If you find an issue, please open a issue on https://github.com/mgehre/xunused or file a pull request.

xunused is compatible with LLVM and Clang versions 14 to 18.

Building and Installation

First download or build the necessary versions of LLVM and Clang with development headers. On Debian and Ubuntu, this can easily be done via http://apt.llvm.org and apt install llvm-18-dev libclang-18-dev. Then build via

mkdir build
cd build
cmake ..
make

If you'd like to build xunused as part of the LLVM build system, make sure to add -DLLVM_EXTERNAL_PROJECTS=xunused -DLLVM_EXTERNAL_XUNUSED_SOURCE_DIR=/path/to/xunused to the cmake options.

Run it

To run the tool, provide a compilation database. By default, it will analyze all files that are mentioned in it.

cd build
./xunused /path/to/your/project/compile_commands.json

You can specify the option -filter together with a regular expressions. Only files who's path is matching the regular expression will be analyzed. You might want to exclude your test's source code to find functions that are only used by tests but not any other code.

If xunused complains about missing include files such as stddef.h, try adding -extra-arg=-I/usr/include/clang/17/include (or similar) to the arguments.

Development

Running Tests

xunused includes a test suite using LLVM's lit testing framework. To run the tests:

cmake --build build --target check

For more information on running and writing tests, see tests/README.md.