- Broad language overhaul: new macro syntax, token‑based quasi‑quoters, tuple structs, automatic move semantics, expanded self‑argument forms, trait inheritance with default methods, and merged module/type namespaces.
- Standard library boost: Timsort, priority‑queue, pipe and serialization overhaul, condition handling, futures moved into std, and many pure functions.
- Tooling and compatibility changes: rustdoc and cargo are now libraries, a REPL added, license switched to dual MIT/APL2, and removal of old .rc crate language and fixed‑length vector syntax.