The 2018 Edition will be the next edition of Rust. The current, and only, Rust edition is 2015. What are Editions? explains that Rust editions are like fuzzy major version numbers, released every two or three years, independent of the actual Rust version number.
Works well in the Ada and SPARK camp. Both had 83 -> 95 -> 2005. Then, Ada 2012 and SPARK 2014 followed.
Sadly the Rust Edition Guide seems broken on iPad (and other mobile devices?) so it’s hard to learn more about these changes.