use std::mem::ManuallyDrop; union Foo<T: ?Sized> { value: ManuallyDrop<T>, //~^ ERROR the size for values of type } struct Foo2<T: ?Sized> { value: ManuallyDrop<T>, //~^ ERROR the size for values of type t: u32, } enum Foo3<T: ?Sized> { Value(ManuallyDrop<T>), //~^ ERROR the size for values of type } fn main() {}