Repr packed Rust example

repr_packed.rs

#[repr(packed)]
#[derive(Debug, Copy, Clone)]
struct Foo {
  tiny: bool,
  normal: u32,
  small: u8,
  long: u64,
  short: u16,
}

macro_rules! raw_dbg {(
    $expr:expr
) => (match $expr { expr => {
    eprintln!("{:#?} = {:#x?}", expr, unsafe {
        ::core::slice::from_raw_parts(
            &expr as *const _ as *const ::std::sync::atomic::AtomicU8,
            ::core::mem::size_of_val(&expr),
        )
    });
    expr
}})}

fn main ()
{
    raw_dbg!(
        Foo {
            tiny: true,
            normal: 2,
            small: 1,
            long: 3,
            short: 4,
        }
    );
}