Since February, the mrustc project [0] has been capable of bootstrapping a relatively-recent Rust compiler from C++. (It currently takes another 8 Rust-to-Rust

Since February, the mrustc project [0] has been capable of bootstrapping a relatively-recent Rust compiler from C++. (It currently takes another 8 Rust-to-Rust steps to reach the latest stable version.) I've personally tested it on my x86_64-linux-gnu machine, but I don't know how tough it would be to get it to support new targets. [0] https://github.com/thepowersgang/mrustc https://github.com/thepowersgang/mrustc