Is anything new really needed here? The problem that the kernel etc. solves with ifdefs and function pointers doesn't seem that different than what one can do w

Is anything new really needed here? The problem that the kernel etc. solves with ifdefs and function pointers doesn't seem that different than what one can do with interface inheritance in just about any OO language. With smart inlining and LTO it can even be efficient. The problem is how to do those platform/feature checks at build time instead of run time, but I'd say that's the build system's problem ('make' or equivalent) not the language's. Ifdef there makes a lot more sense, even for languages that use modules.