The llvm hacking guide has answers to some of these questions: https://clang.llvm.org/hacking.html https://clang.llvm.org/hacking.html There is more information

The llvm hacking guide has answers to some of these questions: https://clang.llvm.org/hacking.html https://clang.llvm.org/hacking.html There is more information in the llvm docs as well. I don't know about a watch mode, but I'm not sure how much that would save you as you'd constantly be relinking a very large project. It might even be counter productive. As for tooling and editors, the build system is well integrated with visual studio on Windows, and I think xcode on mac os. For linting the llvm project has clang-format and clang-tidy which are excellent tools for any C++ project. I believe there is an extensive system test suite written in Python described in the hacking docs.