error[E0599]: no method named `clone` found for struct `Box<dyn Foo>` in the current scope
  --> $DIR/unique-object-noncopyable.rs:24:16
   |
LL | trait Foo {
   | ---------
   | |
   | doesn't satisfy `dyn Foo: Clone`
   | doesn't satisfy `dyn Foo: Sized`
...
LL |     let _z = y.clone();
   |                ^^^^^ method not found in `Box<dyn Foo>`
   | 
  ::: $SRC_DIR/alloc/src/boxed.rs:LL:COL
   |
LL | pub struct Box<T: ?Sized>(Unique<T>);
   | ------------------------------------- doesn't satisfy `Box<dyn Foo>: Clone`
   | 
  ::: $SRC_DIR/core/src/clone.rs:LL:COL
   |
LL |     fn clone(&self) -> Self;
   |        -----
   |        |
   |        the method is available for `Arc<Box<dyn Foo>>` here
   |        the method is available for `Rc<Box<dyn Foo>>` here
   |
   = note: the method `clone` exists but the following trait bounds were not satisfied:
           `dyn Foo: Sized`
           which is required by `Box<dyn Foo>: Clone`
           `dyn Foo: Clone`
           which is required by `Box<dyn Foo>: Clone`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0599`.