4 #![feature(untagged_unions)]
6 use std::mem::ManuallyDrop;
8 union MaybeItem<T: Iterator> {
9 elem: ManuallyDrop<T::Item>,
13 union U<A, B> where A: Copy, B: Copy {
18 unsafe fn union_transmute<A, B>(a: A) -> B where A: Copy, B: Copy {
24 let b = union_transmute::<(u8, u8), u16>((1, 1));
25 assert_eq!(b, (1 << 8) + 1);
27 let v: Vec<u8> = vec![1, 2, 3];
30 let mi = MaybeItem::<std::slice::Iter<_>> { elem: ManuallyDrop::new(i.next().unwrap()) };
31 assert_eq!(**mi.elem, 2);