Rust 1.65 Released: Generic Associated Types and let-else

What happened

Rust 1.65.0 was released on November 3, 2022, per the official Rust blog. Its headline feature, generic associated types, had been in development for more than six years, making its stabilisation a landmark for the language.

Generic associated types

Generic associated types, or GATs, allow lifetime, type and const generics to be defined on associated types within a trait. This unlocks patterns that were previously impossible to express in stable Rust, such as a lending iterator whose items can borrow from the iterator itself, or a trait that is generic over smart-pointer types like Rc or Arc. The Rust team noted it is hard to overstate how useful GATs are, while also documenting the known limitations of the initial stabilisation.

let-else and labeled blocks

Rust 1.65 added let-else statements, a new kind of let with a refutable pattern and a diverging else block that runs when the pattern does not match, letting code bind variables in the surrounding scope or else return, break or panic. The release also allowed break from labeled plain blocks, so a multi-statement block can exit early with a value, replacing the old idiom of a loop that runs only once. On Linux, split debuginfo became stable, which can speed up link times.

Why it mattered

GATs were one of the most anticipated additions to Rust's type system, enabling library authors to express abstractions, like lending iterators, that the language previously could not. Combined with the ergonomic let-else statement, Rust 1.65 was a substantial step forward for both library design and everyday code.

Related on Skillo

See also: Rust 1.56 and the Rust 2021 edition, Rust 1.85 and the Rust 2024 edition.

Sources

• Announcing Rust 1.65.0 (official Rust blog)

Published date reflects the original event date (2022-11-03). This article is original Skillo editorial written from the sources above; facts were verified in September 2026.