src/Tools/Code/code_printer.ML

     fun fillup_param _ (_, SOME v) = v
       | fillup_param x (i, NONE) = x ^ string_of_int i;
     val fished1 = fold (map2 fish_param) lhss (replicate (length (hd lhss)) NONE);
     val x = singleton (Name.variant_list (map_filter I fished1)) "x";
     val fished2 = map_index (fillup_param x) fished1;
-    val (fished3, _) = fold_map Name.variant fished2 Name.context;
+    val fished3 = Name.variants Name.context fished2;
     val vars' = intro_vars fished3 vars;
   in map (lookup_var vars') fished3 end;
 
 fun intro_base_names no_syntax deresolve =
   map_filter (fn name => if no_syntax name then