error[E0277]: the trait bound `Self: std::cmp::Eq` is not satisfied
  --> $DIR/wf-trait-default-fn-arg.rs:21:5
   |
LL | /     fn bar(&self, x: &Bar<Self>) {
LL | |         //~^ ERROR E0277
LL | |         //
LL | |         // Here, Eq ought to be implemented.
LL | |     }
   | |_____^ the trait `std::cmp::Eq` is not implemented for `Self`
   |
   = help: consider adding a `where Self: std::cmp::Eq` bound
note: required by `Bar`
  --> $DIR/wf-trait-default-fn-arg.rs:18:1
   |
LL | struct Bar<T:Eq+?Sized> { value: Box<T> }
   | ^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.