sc_event_or_list compile error in systemC 2.3

I'm using the follwing function. but there is a compile error in systemC 2.3. How to fix it?

struct M: sc_module
{
  sc_port<i_f, 0> p; // Multiport

  sc_event_or_list& all_events() {
    sc_event_or_list& or_list = p[0]->event() | p[0]->event();
    for (int i = 1; i < p.size(); i++)
      or_list | p[i]->event();
    return or_list;
  }
  ...
  wait(all_events());
  ...
 

The compile error is

"error: invalid initialization of non-const reference of type ?sc_core::sc_event_or_list&? from a temporary of type ?sc_core::sc_event_or_expr?"

Thanks,