Rust 2018

RFC#2052, which also proposed the Edition system
Release version1.31.0

The edition system was created for the release of Rust 2018. The release of the Rust 2018 edition coincided with a number of other features all coordinated around the theme of productivity. The majority of those features were backwards compatible and are now available on all editions; however, some of those changes required the edition mechanism (most notably the module system changes).