1 //===----------------------------------------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 // <optional> 11 12 // A program that necessitates the instantiation of template optional for 13 // (possibly cv-qualified) null_opt_t is ill-formed. 14 15 #include <experimental/optional> 16 main()17int main() 18 { 19 #if _LIBCPP_STD_VER > 11 20 using std::experimental::optional; 21 using std::experimental::nullopt_t; 22 using std::experimental::nullopt; 23 24 optional<nullopt_t> opt; 25 #else 26 #error 27 #endif // _LIBCPP_STD_VER > 11 28 } 29