Installation

WeaveC currently ships source releases. Build it against an LLVM/Clang development installation, and keep that LLVM installation available at run time: weavec-cc uses its Clang resources and linker. The CI-tested platforms are macOS and Linux. The runtime that weavec-cc links into the programs it builds supports 64-bit macOS and Linux targets; for any other target weavec-cc builds without it.

1. Install the toolchain

You need CMake 3.25 or newer for the supplied presets, Ninja, a C++20 compiler, and the LLVM/Clang development libraries. LLVM 23.x is recommended; the project supports LLVM 20 and newer. Tests also require lit and LLVM’s FileCheck.

macOS

brew install cmake llvm ninja lit
export WEAVEC_LLVM_PREFIX="$(brew --prefix llvm)"

Apple’s system Clang can compile WeaveC, but the development libraries come from Homebrew’s LLVM package. Xcode does not include them.

Ubuntu / Debian

Install LLVM from the official LLVM packages for your distribution. Review the installer before running it with elevated privileges:

wget https://apt.llvm.org/llvm.sh
less llvm.sh
sudo bash llvm.sh 23 all
sudo apt-get install -y cmake ninja-build python3-venv
python3 -m venv .venv
. .venv/bin/activate
pip install lit==23.1.0
export WEAVEC_LLVM_PREFIX=/usr/lib/llvm-23
export CC=clang-23 CXX=clang++-23

Check cmake --version; older distributions may need a newer CMake installation to use the presets.

2. Get a release

Download the source archive and SHA256SUMS from GitHub Releases into the same directory. Verify the archive with one of:

shasum -a 256 -c SHA256SUMS  # macOS
sha256sum -c SHA256SUMS     # Linux

Extract weavec-X.Y.Z-source.tar.gz, replacing X.Y.Z with the downloaded version, and enter its weavec-X.Y.Z directory.

For development, you can instead clone the current source:

git clone https://github.com/weavefoundry/weavec.git
cd weavec

3. Build, test, and install

Run these commands from the source directory:

cmake --preset release -DWEAVEC_VERSION_SUFFIX=""
cmake --build --preset release
ctest --preset release
cmake --install build/release --prefix "$HOME/.local"
export PATH="$HOME/.local/bin:$PATH"

The install puts weavec-cc in bin/, and weavec.h (under lib/weavec/include/) and the runtime archives (libweavec_rt.a, libweavec_alloc.a) under lib/weavec/. It also installs WeaveC’s C++ libraries, their headers and a CMake package, which compiling C programs does not need. weavec-cc finds the archives relative to its own location, so move the prefix as a whole. Add the PATH export to your shell configuration to retain it in new terminals. Use the developer guide for debug builds, alternative LLVM installations, and build options.

4. Verify the installation

weavec-cc --version

It prints Clang’s version, then weavec-cc version X.Y.Z and the LLVM version it was built with. To check that the runtime links, compile and run an empty program:

printf 'int main(void) { return 0; }\n' > empty.c
weavec-cc empty.c -o empty && ./empty && echo ok

It should print ok with no note about building without the WeaveC runtime. If Clang resources or shared libraries cannot be found, check installation troubleshooting.

Next: Run your first check.