| // run-pass |
| // To work around #46855 |
| // compile-flags: -Z mir-opt-level=0 |
| // Regression test for the inhabitedness of unions with uninhabited variants, issue #46845 |
| |
| use std::mem; |
| |
| #[derive(Copy, Clone)] |
| enum Never { } |
| |
| // A single uninhabited variant shouldn't make the whole union uninhabited. |
| union Foo { |
| a: u64, |
| _b: Never |
| } |
| |
| // If all the variants are uninhabited, however, the union should be uninhabited. |
| // NOTE(#49298) the union being uninhabited shouldn't change its size. |
| union Bar { |
| _a: (Never, u64), |
| _b: (u64, Never) |
| } |
| |
| fn main() { |
| assert_eq!(mem::size_of::<Foo>(), 8); |
| // See the note on `Bar`'s definition for why this isn't `0`. |
| assert_eq!(mem::size_of::<Bar>(), 8); |
| |
| let f = [Foo { a: 42 }, Foo { a: 10 }]; |
| println!("{}", unsafe { f[0].a }); |
| assert_eq!(unsafe { f[1].a }, 10); |
| } |
