bool sys_var_pluginvar::do_check(THD *thd, set_var *var)
{
  st_item_value_holder value;
  DBUG_ASSERT(!is_readonly());
  DBUG_ASSERT(plugin_var->check);

  value.value_type= item_value_type;
  value.val_str= item_val_str;
  value.val_int= item_val_int;
  value.val_real= item_val_real;
  value.is_unsigned= item_is_unsigned;
  value.item= var->value;

  return plugin_var->check(thd, plugin_var, &var->save_result, &value);
}