src/test/run-pass/ctfe/union-ice.rs

   1 // Copyright 2018 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 #![feature(const_fn)]
  12
  13 type Field1 = i32;
  14 type Field2 = f32;
  15 type Field3 = i64;
  16
  17 union DummyUnion {
  18     field1: Field1,
  19     field2: Field2,
  20     field3: Field3,
  21 }
  22
  23 const FLOAT1_AS_I32: i32 = 1065353216;
  24 const UNION: DummyUnion = DummyUnion { field1: FLOAT1_AS_I32 };
  25
  26 const fn read_field1() -> Field1 {
  27     const FIELD1: Field1 = unsafe { UNION.field1 };
  28     FIELD1
  29 }
  30
  31 const fn read_field2() -> Field2 {
  32     const FIELD2: Field2 = unsafe { UNION.field2 };
  33     FIELD2
  34 }
  35
  36 const fn read_field3() -> Field3 {
  37     const FIELD3: Field3 = unsafe { UNION.field3 };
  38     FIELD3
  39 }
  40
  41 fn main() {
  42     assert_eq!(read_field1(), FLOAT1_AS_I32);
  43     assert_eq!(read_field2(), 1.0);
  44     assert_eq!(read_field3(), unsafe { UNION.field3 });
  45 }