tests/ui/union/union-align.rs

   1 // run-pass
   2 // revisions: mirunsafeck thirunsafeck
   3 // [thirunsafeck]compile-flags: -Z thir-unsafeck
   4
   5 #![allow(dead_code)]
   6
   7 use std::mem::{size_of, size_of_val, align_of, align_of_val};
   8
   9 #[repr(align(16))]
  10 pub union U16 {
  11     a: u8,
  12     b: u32
  13 }
  14
  15 fn main() {
  16     assert_eq!(align_of::<U16>(), 16);
  17     assert_eq!(size_of::<U16>(), 16);
  18     let u = U16 { a: 10 };
  19     unsafe {
  20         assert_eq!(align_of_val(&u.a), 1);
  21         assert_eq!(size_of_val(&u.a), 1);
  22         assert_eq!(u.a, 10);
  23     }
  24
  25     let u = U16 { b: 11 };
  26     unsafe {
  27         assert_eq!(align_of_val(&u.b), 4);
  28         assert_eq!(size_of_val(&u.b), 4);
  29         assert_eq!(u.b, 11);
  30     }
  31
  32     hybrid::check_hybrid();
  33 }
  34
  35 mod hybrid {
  36     use std::mem::{size_of, align_of};
  37
  38     #[repr(align(16))]
  39     #[derive(Copy, Clone)]
  40     struct S1 {
  41         a: u16,
  42         b: u8,
  43     }
  44
  45     #[repr(align(32))]
  46     union U {
  47         s: S1,
  48         c: u16,
  49     }
  50
  51     #[repr(align(64))]
  52     struct S2 {
  53         d: u8,
  54         u: U,
  55     }
  56
  57     pub fn check_hybrid() {
  58         assert_eq!(align_of::<S1>(), 16);
  59         assert_eq!(size_of::<S1>(), 16);
  60         assert_eq!(align_of::<U>(), 32);
  61         assert_eq!(size_of::<U>(), 32);
  62         assert_eq!(align_of::<S2>(), 64);
  63         assert_eq!(size_of::<S2>(), 64);
  64     }
  65 }