Building from source

Prebuilt Linux, macOS, and Windows binaries are published on the releases page (the fastest install on Linux/macOS is curl https://cx-language.github.io/cx/install.sh | bash). To compile cx yourself instead (required on platforms without a prebuilt binary, such as Intel Macs), you need a C++20 compiler, CMake 3.16 or newer, and LLVM/Clang 23.

On Linux and macOS, the cx and cx-lsp binaries end up directly in the build directory.

Linux

On Ubuntu/Debian, install the prerequisites with:

wget https://apt.llvm.org/llvm.sh
chmod +x llvm.sh
sudo ./llvm.sh 23 all
sudo apt-get install -y cmake g++ python3-pip

On other distributions, install CMake and a C++ compiler with your package manager, then download and extract the pre-built LLVM/Clang 23 binaries (replace X64 with ARM64 on ARM):

curl -L -O https://github.com/llvm/llvm-project/releases/download/llvmorg-23.1.1/LLVM-23.1.1-Linux-X64.tar.xz
tar -xf LLVM-23.1.1-Linux-X64.tar.xz

Then run the following commands, with <llvm dir> set to /usr/lib/llvm-23 for apt installs or the extracted directory for tarball installs:

mkdir build && cd build
cmake .. -DCMAKE_PREFIX_PATH="<llvm dir>"
cmake --build .

macOS

brew install llvm@23 cmake

Then run the following commands:

mkdir build && cd build
cmake .. -DCMAKE_PREFIX_PATH="$(brew --prefix llvm@23)"
cmake --build .

Windows

Download and extract LLVM/Clang 23 pre-built binaries from https://github.com/llvm/llvm-project/releases.

Run the commands below from an x64 Native Tools Command Prompt for Visual Studio (or any prompt with the VS environment loaded): it puts the Visual Studio bundled CMake, Ninja, and the MSVC compiler on PATH. A cmake.org install works too, but not the MSYS2 CMake, which generates Unix-style paths that break the build.

Before configuring, check the environment:

• Keep MSYS2 off PATH entirely, not just its CMake: CMake may otherwise pick up MSYS2's LibXml2 and leak its GCC-specific headers into the MSVC build (100+ errors mentioning __asm__ or __UINTPTR_TYPE__). If the errors already happened, strip every MSYS2 entry from PATH and configure in a fresh build directory.
• Install Python 3 (the python.org installer provides the py launcher), then install the test runner with py -m pip install lit psutil (python -m pip ... works too; stock Windows provides no python3 alias). The test suite locates the interpreter itself, but the lit executable that pip installs must be on PATH.

mkdir build
cd build
cmake .. -DCMAKE_PREFIX_PATH="C:\path\to\llvm" -DCMAKE_GENERATOR_PLATFORM=x64 -Thost=x64
cmake --build . --config Release

LLVM's Windows binaries require zlib and zstd at configure time. CMake uses system/vcpkg copies when findable (add their install prefix to CMAKE_PREFIX_PATH), and otherwise builds them from source automatically.

The cx and cx-lsp binaries end up in build\Release (build\Debug when built without --config Release). For the fastest clean build of just the compiler, configure with -G Ninja -DCMAKE_BUILD_TYPE=Debug -DCMAKE_UNITY_BUILD=ON and run cmake --build . --target cx.

Offline builds

cmake .. -DFETCHCONTENT_SOURCE_DIR_ZLIB=/path/to/zlib -DFETCHCONTENT_SOURCE_DIR_ZSTD=/path/to/zstd

Where to go next

• Getting started to write your first program.
• Editor setup (cx-lsp is built alongside cx).