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"