(Rust’s epochs we’re renamed “editions” before release. They’re per package, not per file. Projects can use packages from any edition, but all files in a given

(Rust’s epochs we’re renamed “editions” before release. They’re per package, not per file. Projects can use packages from any edition, but all files in a given package have the same edition. This is at least partially because “file” is not really a coherent boundary in Rust.)