Procedural macro for the #[async] attribute.
This crate is an implementation of the #[async] attribute as a procedural
macro. This is nightly-only for now as it's using the unstable features of
procedural macros. Furthermore it's generating code that's using a new
keyword, yield, and a new construct, generators, both of which are also
unstable.
Currently this crate depends on syn and quote to do all the heavy
lifting, this is just a very small shim around creating a closure/future out
of a generator.