Rust editions
Rust's edition mechanism lets the language ship opt-in, backward-incompatible idiom changes on a per-crate basis (2015/2018/2021/2024) so crates on different editions still interoperate without splitting the ecosystem.
grounded in: trends theme 'Rust systems-programming refinement: Front-page debate keeps returning to Rust idioms, editions, and its concurrency model' + this system's Rust/Yew/Cargo stack