Just to expand on the editions things, editions are local to the crate. A Rust 2015 crate can freely use a Rust 2018 crate and the reverse. So davidcuddeback is

Just to expand on the editions things, editions are local to the crate. A Rust 2015 crate can freely use a Rust 2018 crate and the reverse. So davidcuddeback isn't being locked out of using up to date dependencies either.