- Breaking changes introduced to type soundness and associated types, line iteration handling, static‑lifetime loan scope, str::parse rounding behavior, and use‑statement renaming, with some warnings becoming errors in the next release.
- Hundreds of new stable APIs added to the standard library (e.g., Box<str>, Arc, CString, TcpStream timeouts, Vec::append, HashMap/HashSet Extend, etc.) and several older APIs deprecated (BTreeMap/Set with_b, Option/Result slice helpers, ...
- Bug fixes and performance enhancements including fixed VecDeque zero‑size panic, faster string searching, O(1) iterator count/nth/last, improved compiler stack handling, and new Windows MSVC 64‑bit support.
Rust 1.4.0
Official Rust changelog summary with source attribution, release tags, and community reactions.
Track this Rust release note alongside related changelog updates, risky changes, and weekly digest signals from the developer community.
Verify the original release note
Every summary should remain traceable to the original changelog or release source.
Follow this in context
Turn this Rust release note into a weekly digest for the tools you actually use.
Create digestMore Rust changelog updates
Language: allow shortening lifetimes of &mut during unsize coercions and introduce new lints for invalid runtime symbols and c void return types.