error[E0382]: borrow of moved value: `x`
  --> $DIR/borrowck-loan-in-overloaded-op.rs:21:20
   |
LL |     let x = Foo(box 3);
   |         - move occurs because `x` has type `Foo`, which does not implement the `Copy` trait
LL |     let _y = {x} + x.clone(); // the `{x}` forces a move to occur
   |               -    ^ value borrowed here after move
   |               |
   |               value moved here

error: aborting due to previous error

For more information about this error, try `rustc --explain E0382`.