error: concrete type differs from previous defining opaque type use
  --> $DIR/generic_duplicate_param_use8.rs:13:1
   |
LL | / fn three<T: Debug, U: Debug>(_: T, u: U) -> Two<T, U> {
LL | |
LL | |     (u, 4u32)
LL | | }
   | |_^ expected `(T, u32)`, got `(U, u32)`
   |
note: previous use here
  --> $DIR/generic_duplicate_param_use8.rs:9:1
   |
LL | / fn two<T: Debug, U: Debug>(t: T, _: U) -> Two<T, U> {
LL | |     (t, 4u32)
LL | | }
   | |_^

error: aborting due to previous error