#[repr(align(16))]
struct Unsigned8 {
    v: u8,
}
#[repr(align(16))]
struct Foo {
    a: Unsigned8,
    b: Unsigned8
}



fn main() {
    use std::mem;

    let foo = unsafe { mem::uninitialized::<Foo>() };

    let foo_ptr : *const u8 = unsafe { mem::transmute(&foo) };
    let a_ptr : *const u8 = unsafe { mem::transmute(&foo.a) };
    let b_ptr : *const u8 = unsafe { mem::transmute(&foo.b) };

    let offset_a = (a_ptr as usize) - (foo_ptr as usize);
    let offset_b = (b_ptr as usize) - (foo_ptr as usize);

    println!("a={}, b={}", offset_a, offset_b);
}