I solved this in a method I quite like: profiles and composition. This enables nearly the same flexibility, albeit in a different format, as CMake. We also get

I solved this in a method I quite like: profiles and composition. This enables nearly the same flexibility, albeit in a different format, as CMake. We also get to avoid debugging complex CMake scripts. So you can have a debug a debug profile and asan profile and compose them into a "debug + asan" profile. Catalyst also has hooks, to address the issue you mentioned about needing external scripts.