## Rust 2021 Edition nikomatsakis, m-ou-se --- ### [Rust 2021 is coming!](https://blog.rust-lang.org/2021/05/11/edition-2021.html)  --- ### Rust 2021 is different * Focused on a few discrete changes * Not meant as an overview of the last 3 years --- ### Prelude additions ```rust let rust = Vec::from_iter(...); let is = really.try_from(); let great = huzzah.try_into(); ``` --- ### Cargo resolver The new feature resolver no longer merges all requested features for crates that are depended on in multiple ways. --- ### IntoIterator for arrays ```rust // *All* editions (Rust 1.53): for x in [1, 2, 3] { .. } // Only in Rust 2021: let mut it = [1, 2, 3].into_iter(); it.next().unwrap() // this is an i32, not &i32! ``` --- ### Disjoint capture This compiles: ```rust self.vector.retain(|elem| value > self.threshold) // -------------- // // Closure captures `self.threshold`, not `self`. ``` --- ### Panic macro consistency Panic is the same on std/core, and formatting works. ```rust panic!("{}", foo); // works panic!("{}"); // error panic!("") panic_any!("{}"); // panics w/ the string `{}` ``` Enables upcoming `{foo}` notation: ```rust println!("{foo}"); // Any edition panic!("{foo}"); // Only Rust 2021 ``` --- ### Reserved syntax Unknown prefixes now error in the lexer: * on identifiers, e.g. `foo#bar` * on strings, e.g. `f#"..."` * on numbers, e.g. `k33` --- ### How can I help? Our [project board](https://github.com/orgs/rust-lang/projects/7) contains remaining blockers --- ### Thanks! Too many people to thank! Some major contributors: * rylev * ehuss * cuviper * arora-aman and RFC 2229 project group * simulacrum * bstrie * mark-i-m * hi-rustin * djc