This issue has been greatly reduce since Rust 1.0 came out as more language features are stabilized. Just in 2017, Diesel (ORM) and Serde (serialization) have s

This issue has been greatly reduce since Rust 1.0 came out as more language features are stabilized. Just in 2017, Diesel (ORM) and Serde (serialization) have started being fully functional on stable Rust. Rocket is one of a rapidly shrinking set of libraries that relies on unstable features. As long as Rocket doesn't add a dependency on more unstable features, it too will join the ranks of stable-compatible crates soon.