35 lines
729 B
Rust
35 lines
729 B
Rust
// run-pass
|
|
// revisions: mirunsafeck thirunsafeck
|
|
// [thirunsafeck]compile-flags: -Z thir-unsafeck
|
|
|
|
#![allow(dead_code)]
|
|
|
|
use std::mem::ManuallyDrop;
|
|
|
|
union MaybeItem<T: Iterator> {
|
|
elem: ManuallyDrop<T::Item>,
|
|
none: (),
|
|
}
|
|
|
|
union U<A, B> where A: Copy, B: Copy {
|
|
a: A,
|
|
b: B,
|
|
}
|
|
|
|
unsafe fn union_transmute<A, B>(a: A) -> B where A: Copy, B: Copy {
|
|
U { a }.b
|
|
}
|
|
|
|
fn main() {
|
|
unsafe {
|
|
let b = union_transmute::<(u8, u8), u16>((1, 1));
|
|
assert_eq!(b, (1 << 8) + 1);
|
|
|
|
let v: Vec<u8> = vec![1, 2, 3];
|
|
let mut i = v.iter();
|
|
i.next();
|
|
let mi = MaybeItem::<std::slice::Iter<_>> { elem: ManuallyDrop::new(i.next().unwrap()) };
|
|
assert_eq!(**mi.elem, 2);
|
|
}
|
|
}
|