tl;dr: Rust is now a Tier-1 language at Microsoft, receiving the same internal engineering support as C++, C#, and TypeScript. To enable this, Microsoft built `rustc_codegen_utc`, an alternative rustc backend that plugs into MSVC's code generator ("UTC"), giving Rust access to Windows ABI compatibility, security hardening, hotpatching, debugging tools, and cross-language optimization with C++. It's been self-hosted since Rust 1.90 and is used by 100+ internal Microsoft repos, providing a unified codegen foundation for hybrid Rust/C++ projects on Windows.