Rust call C

foo.c

void* hello_world() {
  printf("hello, world");
}

main.rs

#[link(name = "foo")]
extern "C" {
    fn hello_world() -> ();
}

fn main() {
    unsafe { hello_world(); }
}

Makefile

default:
	gcc -g -c foo.c -o foo.o
	ar rcs libfoo.a foo.o
	rustc main.rs -L .