Bad Rust

nasty.rs

struct A {
    value: *mut i64,
}

impl A {
    fn new() -> A {
	A{value: std::ptr::null_mut()}
    }
}

fn dostuff(val: &i64, ia: &A) {
    unsafe {
	let a = val as *const i64 as *mut i64;
	let b = ia as *const A as *mut A;
	*a = 100;
	(*b).value = a;
    }
}

fn main() {
    let ia = A::new();
    let a = 10;
    dostuff(&a, &ia);
    unsafe {
	println!("{}", *(ia.value));
    }
}