std::uv ? lightweight threads similar to go-routines, greenlets of gevent (Python), or Node.js.

EDIT: Mea culpa, it used to have. (ref. http://stackoverflow.com/questions/29428318/why-did-rust-rem...)

Well, you can always build your own interfaces to achieve a similar result. But why do you need go-routines ?

By the way, at least, Rust tries to handle concurrency the most he can (by analyzing if data race can occur, at compile-time for example).

What do you need more ?