error[E0277]: the trait bound `foo::issue_1920::S: std::clone::Clone` is not satisfied
  --> $DIR/issue-1920-1.rs:12:5
   |
LL | fn assert_clone<T>() where T : Clone { }
   | ------------------------------------ required by `assert_clone`
...
LL |     assert_clone::<foo::issue_1920::S>();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::clone::Clone` is not implemented for `foo::issue_1920::S`

error: aborting due to previous error

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