error[E0277]: the trait bound `Bar: std::hash::Hash` is not satisfied
  --> $DIR/issue-21160.rs:8:12
   |
LL | struct Foo(Bar);
   |            ^^^ the trait `std::hash::Hash` is not implemented for `Bar`
   |
   = note: required by `std::hash::Hash::hash`

error: aborting due to previous error

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