I misunderstood, but what you're actually advocating has all the problems I mentioned only even more so. Any tool that you want to apply to your codebase will have to understand not just a macro, but your build configuration.
How would you do it without using the preprocessor? Honest question. You could leverage the build system to do that instead but that seems even worse to me... You are effectively hoisting an implementation detail up into the build system.
Like the other commenter said, I'd rather do simple, virtual calls and then fix it using LTO.
