Comment by devy

Aight! Fable 5.1 summary says this is about Microsoft built, self-hosts, and runs in production a proprietary-backend codegen for rustc that bypasses LLVM on Windows. The vehicle is rustc_codegen_utc, an alternative rustc backend in the same family as the LLVM, GCC, and Cranelift backends, wired to the MSVC backend ("UTC").