| // Copyright 2018 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| #![feature(const_fn)] |
| |
| type Field1 = i32; |
| type Field2 = f32; |
| type Field3 = i64; |
| |
| union DummyUnion { |
| field1: Field1, |
| field2: Field2, |
| field3: Field3, |
| } |
| |
| const FLOAT1_AS_I32: i32 = 1065353216; |
| const UNION: DummyUnion = DummyUnion { field1: FLOAT1_AS_I32 }; |
| |
| const fn read_field1() -> Field1 { |
| const FIELD1: Field1 = unsafe { UNION.field1 }; |
| FIELD1 |
| } |
| |
| const fn read_field2() -> Field2 { |
| const FIELD2: Field2 = unsafe { UNION.field2 }; |
| FIELD2 |
| } |
| |
| const fn read_field3() -> Field3 { |
| const FIELD3: Field3 = unsafe { UNION.field3 }; //~ ERROR cannot be used |
| FIELD3 |
| } |
| |
| fn main() { |
| assert_eq!(read_field1(), FLOAT1_AS_I32); |
| assert_eq!(read_field2(), 1.0); |
| assert_eq!(read_field3(), unsafe { UNION.field3 }); |
| } |