Include crates recommended as part of the compiler output #718
Description
If you grep https://crates.io/crates/ in *.stderr files in Rust compiler's source code, you will find there are two crates currently mentioned: async-trait and async-recursion, which are useful crates to workaround some of annoying restrictions Rust currently has.
async-trait has already been included, and I think it would be good to include async-recursion as well, so that people can try out it when the compiler asks them to.