anchor.diff:  
   t_shutdown_async(Config) when is_list(Config) ->
       {OS, _} = os:type(),
  -    {ok, L} = gen_tcp:listen(0, [{sndbuf, 4096}]),
  +    {ok, L} = gen_tcp:listen(0, ?INET_BACKEND_OPTS(Config) ++ [{sndbuf, 4096}]),
       {ok, Port} = inet:port(L),
       {ok, Client} = gen_tcp:connect(localhost, Port,
  -				   [{recbuf, 4096},
  -				    {active, false}]),
  +				   ?INET_BACKEND_OPTS(Config) ++
  +                                       [{recbuf, 4096},
  +                                        {active, false}]),
       {ok, S} = gen_tcp:accept(L),
       PayloadSize = 1024 * 1024,
       Payload = lists:duplicate(PayloadSize, $.),
  
positive.code: 
  all() -> 
      [
       {group, t_accept},
       {group, t_connect},
       {group, t_recv},
       {group, t_shutdown},
       t_fdopen, t_fdconnect, t_implicit_inet6, t_accept_inet6_tclass,
       {group, t_local},
       {group, s_misc}
      ].
  
  groups() -> 
      [
       {t_accept,   [], t_accept_cases()},
       {t_connect,  [], t_connect_cases()},
       {t_recv,     [], t_recv_cases()},
       {t_shutdown, [], t_shutdown_cases()},
       {t_local,    [], t_local_cases()},
       {s_misc,     [], s_misc_cases()}
      ].
  
  t_accept_cases() ->
      [
  
negative.code: 
  %% Test that gen_tcp:accept/2 (with timeout) works.
  t_accept_timeout(Config) when is_list(Config) ->
      {ok, L} = gen_tcp:listen(0, ?INET_BACKEND_OPTS(Config)),
      timeout({gen_tcp, accept, [L, 200]}, 0.2, 1.0).
  
  %%% gen_tcp:connect/X
  