Unless you're using one of the gcc rust compiler reimplementations it only ever uses LLVM. MSVC can't compile rust, and the rust compiler can't use MSVC to comp

Unless you're using one of the gcc rust compiler reimplementations it only ever uses LLVM. MSVC can't compile rust, and the rust compiler can't use MSVC to compile things. What rust & LLVM support is various ABIs on windows, meaning your rust code can link windows libraries (and the other way around).