Test more related cases

Author: oli-obk

src/test/ui/existential_types/generic_duplicate_param_use7.rs

@@ -14,3 +14,12 @@ fn two<T: Debug + Copy, U>(t: T, u: U) -> Two<T, U> {
 fn three<T: Debug, U>(t: T, t2: T, u: U) -> Two<T, U> {
     (t, t2)
 }
+
+fn four<T: Debug, U, V>(t: T, t2: T, u: U, v: V) -> Two<T, U> {
+    (t, t2)
+}
+
+fn five<X, Y: Debug>(x: X, y: Y, y2: Y) -> Two<Y, X> {
+    (y, y2)
+}
+