// only-x86_64 type Field1 = i32; type Field2 = f32; type Field3 = i64; #[repr(C)] 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 evaluation of constant value failed //~| uninitialized FIELD3 } fn main() { assert_eq!(read_field1(), FLOAT1_AS_I32); assert_eq!(read_field2(), 1.0); assert_eq!(read_field3(), unsafe { UNION.field3 }); }