Async fn in traits

The Rust language capability (built on return-position impl-Trait-in-traits) that lets trait methods be declared `async`, enabling libraries to abstract over asynchronous behavior behind trait interfaces without external macros or boxing.

grounded in: Trend theme: 'Deep Rust ecosystem debates about async concurrency and language editions are drawing sustained interest'; grounded in the established Rust async trait-abstraction milestone.

Connected concepts

Function coloring, Async runtime, Trait-based polymorphism, Rust editions, Poll-based futures