+check_pred_ty _ (ClassSCCtxt _) (EqPred _ _)
+ = -- We do not yet support superclass equalities.
+ failWithTc $
+ sep [ ptext (sLit "The current implementation of type families does not")
+ , ptext (sLit "support equality constraints in superclass contexts.")
+ , ptext (sLit "They are planned for a future release.")
+ ]
+