The closest thing i am aware of is mrustc: https://github.com/thepowersgang/mrustc https://github.com/thepowersgang/mrustc But AIUI that is not aimed at being

The closest thing i am aware of is mrustc: https://github.com/thepowersgang/mrustc https://github.com/thepowersgang/mrustc But AIUI that is not aimed at being a Rust compiler you would actually use day-to-day, just at being a way to bootstrap a Rust toolchain without needing a Rust compiler.