src/test/ui/union/union-align.rs

   1 // run-pass
   2 #![allow(dead_code)]
   3
   4 use std::mem::{size_of, size_of_val, align_of, align_of_val};
   5
   6 #[repr(align(16))]
   7 pub union U16 {
   8     a: u8,
   9     b: u32
  10 }
  11
  12 fn main() {
  13     assert_eq!(align_of::<U16>(), 16);
  14     assert_eq!(size_of::<U16>(), 16);
  15     let u = U16 { a: 10 };
  16     unsafe {
  17         assert_eq!(align_of_val(&u.a), 1);
  18         assert_eq!(size_of_val(&u.a), 1);
  19         assert_eq!(u.a, 10);
  20     }
  21
  22     let u = U16 { b: 11 };
  23     unsafe {
  24         assert_eq!(align_of_val(&u.b), 4);
  25         assert_eq!(size_of_val(&u.b), 4);
  26         assert_eq!(u.b, 11);
  27     }
  28
  29     hybrid::check_hybrid();
  30 }
  31
  32 mod hybrid {
  33     use std::mem::{size_of, align_of};
  34
  35     #[repr(align(16))]
  36     #[derive(Copy, Clone)]
  37     struct S1 {
  38         a: u16,
  39         b: u8,
  40     }
  41
  42     #[repr(align(32))]
  43     union U {
  44         s: S1,
  45         c: u16,
  46     }
  47
  48     #[repr(align(64))]
  49     struct S2 {
  50         d: u8,
  51         u: U,
  52     }
  53
  54     pub fn check_hybrid() {
  55         assert_eq!(align_of::<S1>(), 16);
  56         assert_eq!(size_of::<S1>(), 16);
  57         assert_eq!(align_of::<U>(), 32);
  58         assert_eq!(size_of::<U>(), 32);
  59         assert_eq!(align_of::<S2>(), 64);
  60         assert_eq!(size_of::<S2>(), 64);
  61     }
  62 }