It's true that if this project succeeds, that would be an outcome, but it's probably worth noting that you'd really only have to add support for the GCC backend

It's true that if this project succeeds, that would be an outcome, but it's probably worth noting that you'd really only have to add support for the GCC backend to do that, and not reimplement the frontend as well (parsing, type checking, lifetime checking, etc.). There's an unrelated project working to do that: https://github.com/antoyo/rustc_codegen_gcc https://github.com/antoyo/rustc_codegen_gcc that would likely yield those same benefits for less effort.