marxin@marxinbox:/tmp> cat dns-stuff.i
struct dns_options {
  struct {
    void *a;
    int b;
  };
  int *socks_host;
  char *socks_user;
  char *socks_password;
};
static char tor_socks_user[1], tor_socks_password[1];
struct {
  int socks_host;
} libdns;
int d;
int *c();
int ax() {
  int *az;
  int ba;
  az = c((&__extension__({
           (struct dns_options){{0, 0},
                                0,
                                0,
                                .socks_host = &libdns.socks_host,
                                .socks_user = tor_socks_user,
                                .socks_password = tor_socks_password};
         })),
         &ba);
  d = *az;
  return 0;
}
marxin@marxinbox:/tmp> gcc dns-stuff.i
dns-stuff.i: In function ‘ax’:
dns-stuff.i:19:11: error: lvalue required as unary ‘&’ operand
   19 |   az = c((&__extension__({
      |           ^