The current behavior is to enforce CMAKE_BUILD_TYPE='RelWithDebInfo' in all cases, no way to override this to build a 'Debug' version of sys-devel/lvvm to investigate crashes :( Of course, the generated CMakeCache.txt files can be manually edited afterwards but it would be more convenient to not do that.
Does MYCMAKEARGS="-DCMAKE_BUILD_TYPE=Debug" work for you as an environment variable?
Your suggestion is working :) -- <<< Gentoo configuration >>> Build type Debug Install path /usr/lib/llvm/16 Let's close this bug, nothing more to do.