src/test/ui/repr_c_int_align.rs

   1 // run-pass
   2 // compile-flags: -O
   3
   4 #![allow(dead_code)]
   5
   6 #[repr(C, u8)]
   7 enum ReprCu8 {
   8     A(u16),
   9     B,
  10 }
  11
  12 #[repr(u8)]
  13 enum Repru8 {
  14     A(u16),
  15     B,
  16 }
  17
  18 #[repr(C)]
  19 struct ReprC {
  20     tag: u8,
  21     padding: u8,
  22     payload: u16,
  23 }
  24
  25 fn main() {
  26     // Test `repr(C, u8)`.
  27     let r1 = ReprC { tag: 0, padding: 0, payload: 0 };
  28     let r2 = ReprC { tag: 0, padding: 1, payload: 1 };
  29
  30     let t1: &ReprCu8 = unsafe { std::mem::transmute(&r1) };
  31     let t2: &ReprCu8 = unsafe { std::mem::transmute(&r2) };
  32
  33     match (t1, t2) {
  34         (ReprCu8::A(_), ReprCu8::A(_)) => (),
  35         _ => assert!(false)
  36     };
  37
  38     // Test `repr(u8)`.
  39     let t1: &Repru8 = unsafe { std::mem::transmute(&r1) };
  40     let t2: &Repru8 = unsafe { std::mem::transmute(&r2) };
  41
  42     match (t1, t2) {
  43         (Repru8::A(_), Repru8::A(_)) => (),
  44         _ => assert!(false)
  45     };
  46 }