src/Pure/Isar/class.ML

         |> add_class_const_def (class, ((c', (rhs, typidx)), def'))
       end;
   in
     thy
     |> Sign.add_path prfx
-    |> Sign.add_consts_authentic [(c, ty', syn')]
+    |> Sign.add_consts_authentic [] [(c, ty', syn')]
     |> Sign.parent_path
     |> Sign.sticky_prefix prfx
     |> PureThy.add_defs_i false [(def, [])]
     |-> (fn [def] => interpret def)
     |> Sign.add_const_constraint (c', SOME ty'')