src/Tools/Code/code_target.ML

     val width = the_default default_width some_width;
   in (fn program => prepared_serializer program width, prepared_program) end;
 
 fun invoke_serializer thy target some_width module_name args naming program names =
   let
+    val check = if module_name = "" then I else check_name true;
     val (mounted_serializer, prepared_program) = mount_serializer thy
-      target some_width module_name args naming program names;
+      target some_width (check module_name) args naming program names;
   in mounted_serializer prepared_program end;
 
 fun assert_module_name "" = error "Empty module name not allowed here"
   | assert_module_name module_name = module_name;