'prop up'? I don't follow your reasoning, GCC does not exist for Linux. As for Linux relying on GCC, Linux relies on lots of GCC compiler extensions, many exte

'prop up'? I don't follow your reasoning, GCC does not exist for Linux. As for Linux relying on GCC, Linux relies on lots of GCC compiler extensions, many extensions which exists as a direct result of requests from kernel developers. You need to patch both Linux and Clang/LLVM to be able to even compile Linux with Clang/LLVM, and the result is unstable, so it's not as if Linux is a 'holdout' by any measure.