You use a "build script" to hook into the compilation process and have it invoke the build of whatever it is you're trying to additionally build. And if it's n

You use a "build script" to hook into the compilation process and have it invoke the build of whatever it is you're trying to additionally build. And if it's not that big, say, a single C file, you can just invoke the C compiler. An example: https://crates.io/crates/cc https://crates.io/crates/cc