static mut DROP_RAN: isize = 0; struct Foo; impl Drop for Foo { fn drop(&mut self) { unsafe { DROP_RAN += 1; } } } struct Fat<T: ?Sized> { f: T } pub fn main() { { let _x: Box<Fat<[Foo]>> = Box::<Fat<[Foo; 3]>>::new(Fat { f: [Foo, Foo, Foo] }); } unsafe { assert_eq!(DROP_RAN, 3); } }