It doesn't. Indeed, when it comes to libc and other system libraries (or really most C libraries in general), the Rust ecosystem relies on hardcoding the ABI o

It doesn't. Indeed, when it comes to libc and other system libraries (or really most C libraries in general), the Rust ecosystem relies on hardcoding the ABI of every supported platform. It's theoretically possible to use bindgen (which parses C headers) as a build step, but this is rarely done.