With much persistence, I've been able to get msc-generator built on a new Macbook Pro running MacOS 10.15.6 Catalina. Below is what I did (I hope I captured it all). Some of it may not have been necessary, but, hey, it worked. Finally! Here's the sequence: ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" Run Xcode.app Let it install whatever it asks about brew install pkg-config brew install zlib brew install graphviz brew install cairo brew install bison...