src/test/ui/union/union-pat-refutability.rs

   1 // run-pass
   2 // revisions: mirunsafeck thirunsafeck
   3 // [thirunsafeck]compile-flags: -Z thir-unsafeck
   4
   5 #![allow(dead_code)]
   6 #![allow(illegal_floating_point_literal_pattern)]
   7
   8 #[repr(u32)]
   9 enum Tag { I, F }
  10
  11 #[repr(C)]
  12 union U {
  13     i: i32,
  14     f: f32,
  15 }
  16
  17 #[repr(C)]
  18 struct Value {
  19     tag: Tag,
  20     u: U,
  21 }
  22
  23 fn is_zero(v: Value) -> bool {
  24     unsafe {
  25         match v {
  26             Value { tag: Tag::I, u: U { i: 0 } } => true,
  27             Value { tag: Tag::F, u: U { f: 0.0 } } => true,
  28             _ => false,
  29         }
  30     }
  31 }
  32
  33 union W {
  34     a: u8,
  35     b: u8,
  36 }
  37
  38 fn refut(w: W) {
  39     unsafe {
  40         match w {
  41             W { a: 10 } => {
  42                 panic!();
  43             }
  44             W { b } => {
  45                 assert_eq!(b, 11);
  46             }
  47         }
  48     }
  49 }
  50
  51 fn main() {
  52     let v = Value { tag: Tag::I, u: U { i: 1 } };
  53     assert_eq!(is_zero(v), false);
  54
  55     let w = W { a: 11 };
  56     refut(w);
  57 }