Refusing to link macOS provided/shadowed software: llvm If you need to have llvm first in your PATH, run: echo 'export PATH="/usr/local/opt/llvm/bin:$PATH"' >> /Users/runner/.bash_profile For compilers to find llvm you may need to set: export LDFLAGS="-L/usr/local/opt/llvm/lib" export CPPFLAGS="-I/usr/local/opt/llvm/include" For cmake to find llvm you may need to set: export CMAKE_PREFIX_PATH="/usr/local/opt/llvm"