Error code E0328

The Unsize trait should not be implemented directly. All implementations of Unsize are provided automatically by the compiler.

Erroneous code example:

#![allow(unused)] #![feature(unsize)] fn main() { use std::marker::Unsize; pub struct MyType; impl<T> Unsize<T> for MyType {} }

If you are defining your own smart pointer type and would like to enable conversion from a sized to an unsized type with the DST coercion system, use CoerceUnsized instead.

#![allow(unused)] #![feature(coerce_unsized)] fn main() { use std::ops::CoerceUnsized; pub struct MyType<T: ?Sized> { field_with_unsized_type: T, } impl<T, U> CoerceUnsized<MyType<U>> for MyType<T> where T: CoerceUnsized<U> {} }