View Compilation Error

0_0_36898707_16549.cpp:14:22: error: 'getnext' function uses 'auto' type specifier without trailing return type
  auto getnext(node* p) { return !flag ? p->next : p->prev; }
                      ^
0_0_36898707_16549.cpp:14:22: note: deduced return type only available with -std=c++1y or -std=gnu++1y