error[E0277]: the trait bound `U: std::marker::Copy` is not satisfied
  --> $DIR/wf-fn-where-clause.rs:8:24
   |
LL | trait ExtraCopy<T:Copy> { }
   |                   ---- required by this bound in `ExtraCopy`
LL | 
LL | fn foo<T,U>() where T: ExtraCopy<U>
   |                        ^^^^^^^^^^^^ the trait `std::marker::Copy` is not implemented for `U`
   |
help: consider further restricting type parameter `U`
   |
LL | fn foo<T,U>() where T: ExtraCopy<U>, U: std::marker::Copy
   |                                    ^^^^^^^^^^^^^^^^^^^^^^

error[E0277]: the size for values of type `(dyn std::marker::Copy + 'static)` cannot be known at compilation time
  --> $DIR/wf-fn-where-clause.rs:12:16
   |
LL | fn bar() where Vec<dyn Copy>:, {}
   |                ^^^^^^^^^^^^^ doesn't have a size known at compile-time
...
LL | struct Vec<T> {
   |            - required by this bound in `Vec`
   |
   = help: the trait `std::marker::Sized` is not implemented for `(dyn std::marker::Copy + 'static)`
   = note: to learn more, visit <https://doc.rust-lang.org/book/ch19-04-advanced-types.html#dynamically-sized-types-and-the-sized-trait>
help: you could relax the implicit `Sized` bound on `T` if it were used through indirection like `&T` or `Box<T>`
  --> $DIR/wf-fn-where-clause.rs:16:12
   |
LL | struct Vec<T> {
   |            ^ this could be changed to `T: ?Sized`...
LL |     t: T,
   |        - ...if indirection was used here: `Box<T>`

error[E0038]: the trait `std::marker::Copy` cannot be made into an object
  --> $DIR/wf-fn-where-clause.rs:12:16
   |
LL | fn bar() where Vec<dyn Copy>:, {}
   |                ^^^^^^^^^^^^^ the trait `std::marker::Copy` cannot be made into an object
   |
   = note: the trait cannot be made into an object because it requires `Self: Sized`

error: aborting due to 3 previous errors

Some errors have detailed explanations: E0038, E0277.
For more information about an error, try `rustc --explain E0038`.