Define compiler intermediate representation usable by external tools

Working on refactoring unsafety checking to operate on THIR

Improving rustc compilation performance (build times)

Soundly expanding the capabilities of compile-time function evaluation in Rust

Providing users with a great experience when debugging Rust code

Aiming to make rustc better at telling the user why the compiler isn't smart enough to understand their code yet

Improving incremental compilation in rustc

Working with LLVM upstream to represent Rust in its development

Organizing and managing the Rust compiler team

Writing MIR optimizations and refactoring the MIR to be more optimizable

Implementing the new MIR-based borrow checker and non-lexical lifetimes in Rust

Making parallel compilation the default for rustc

Sharing the parser between rustc and rust-analyzer

Implementing profile-guided optimization for rustc

Working on an experimental new borrow-checker implementation

Implementing polymorphization to reduce unnecessary monomorphisation in rustc

Triaging bugs, mainly deciding if bugs are critical (potential release blockers) or not

Improving the behavior of closure-capture, and improving the documentation on closures

Experimenting with a new compiler architecture tailored for IDEs

Making the compiler easier to learn by maintaining and improving the Rustc Dev Guide

Helping new and experienced contributors learn more about rustc

Improving the -Z self-profile feature of the Rust compiler

Improving the trait checker and related language features