Rust doesn't make much use of libc on Windows; it mostly bypasses libc and makes direct calls to the Windows API. AFAIK it only uses a few functions like memcpy

Rust doesn't make much use of libc on Windows; it mostly bypasses libc and makes direct calls to the Windows API. AFAIK it only uses a few functions like memcpy, memset, memcmp (LLVM itself emits calls to these) and the math library (sin, atan2 etc.) from the Microsoft libc.