error[E0599]: no method named `clone` found for struct `std::boxed::Box<dyn Foo>` in the current scope
  --> $DIR/unique-object-noncopyable.rs:24:16
   |
LL | trait Foo {
   | ---------
   | |
   | doesn't satisfy `dyn Foo: std::clone::Clone`
   | doesn't satisfy `dyn Foo: std::marker::Sized`
...
LL |     let _z = y.clone();
   |                ^^^^^ method not found in `std::boxed::Box<dyn Foo>`
   | 
  ::: $SRC_DIR/liballoc/boxed.rs:LL:COL
   |
LL | pub struct Box<T: ?Sized>(Unique<T>);
   | ------------------------------------- doesn't satisfy `std::boxed::Box<dyn Foo>: std::clone::Clone`
   |
   = note: the method `clone` exists but the following trait bounds were not satisfied:
           `dyn Foo: std::marker::Sized`
           which is required by `std::boxed::Box<dyn Foo>: std::clone::Clone`
           `dyn Foo: std::clone::Clone`
           which is required by `std::boxed::Box<dyn Foo>: std::clone::Clone`
   = help: items from traits can only be used if the trait is implemented and in scope
   = note: the following trait defines an item `clone`, perhaps you need to implement it:
           candidate #1: `std::clone::Clone`

error: aborting due to previous error

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