For those building LLVM. I haven't included any of the other associated packages that you may be building at the same time here>
First, you need to get from the LLVM GitHub the releases for 3 packages, not just the normal 2:
* LLVM 15.0.0
* Clang 15.0.0
* CMake 15.0.0 - this last one is NOT the source to 'cmake' but rather
the 'cmake package' that contains common information LLVM's use of CMake
requires to build. Therefore users need to be warned there will be two
different tarballs with the name cmake as a result - one for building CMake -
one for being part of the build of LLVM.
Have fun!