src/Pure/codegen.ML

           in x ^ " called by " ^ y ^ "\n" ^ string_of_cycle (b :: cs) end
       | string_of_cycle _ = ""
   in
     if module = "" then
       let
-        val modules = distinct (map (#2 o snd) code);
+        val modules = gen_distinct (op =) (map (#2 o snd) code);
         val mod_gr = foldr (uncurry Graph.add_edge_acyclic)
           (foldr (uncurry (Graph.new_node o rpair ())) Graph.empty modules)
           (List.concat (map (fn (s, (_, module, _)) => map (pair module)
             (filter_out (equal module) (map (#2 o Graph.get_node gr)
               (Graph.imm_succs gr s)))) code));