ppr_co :: TyPrec -> TcCoercion -> SDoc
ppr_co _ (TcRefl r ty) = angleBrackets (ppr ty) <> ppr_role r
ppr_co :: TyPrec -> TcCoercion -> SDoc
ppr_co _ (TcRefl r ty) = angleBrackets (ppr ty) <> ppr_role r
ppr_co _ (TcRefl r ty) = angleBrackets (ppr ty) <> ppr_role r