Rustacean Station What's New in the Rust 2024 Edition
Jan 23, 2026
A lively tour of the Rust 2024 Edition's biggest language and tooling changes. They hit RPIT lifetime capture rules, let-chain and temporary drop behavior, and match ergonomics restrictions. Unsafe-related shifts get lots of attention, from extern blocks to newly unsafe std functions. Cargo and rustdoc updates, macro fragment changes, and a reserved gen keyword round out the conversation.
AI Snips
Chapters
Transcript
Episode notes
Simpler RPIT Lifetime Capture Rules
- RPIT (return-position impl trait) now captures all in-scope generic and lifetime parameters by default, making lifetime behavior consistent across async, traits, and normal functions.
- Use the new +use<> syntax to opt out and explicitly control which lifetimes or generics are captured.
Temporaries Get Shorter, More Intuitive Lifetimes
- The 2024 edition shortens temporary lifetimes for if-let, let-chains, and tail expressions to match intuitive drop points and fix mismatches from desugaring to match.
- This reduces surprises but can break code relying on previous temporary lifetimes, especially around mutex guards and drop timing.
Bind Temporaries When Drop Timing Matters
- Avoid relying on implicit temporary drop order; create explicit bindings when you need a value to live longer.
- Use named let bindings to control destructor timing and prevent deadlocks with mutex guards.