Rust-ABI calls across dynamic libraries

eggman.rs

#![crate_type="dylib"]

#[no_mangle]
pub fn foo(x: std::fmt::Arguments) -> i32 {
    println!("{:?}", x);
    3
}

walrus.rs

#[link(name="dl")]
extern {
    fn dlopen(filename: *const u8, flags: isize) -> *const u8;
    fn dlsym(handle: *const u8, symbol: *const u8) -> *const u8;
}

fn main() {
    let eggman = unsafe { dlopen(b"${ORIGIN}/libeggman.so\0" as *const _, 2) };
    let foo: fn(x: std::fmt::Arguments) -> i32 = unsafe {
        std::mem::transmute(dlsym(eggman, b"foo\0" as *const _))
    };
    println!("{}", foo(format_args!("{}", 17)));
}