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 a 13// reference type is ill-formed. 14 15#include <experimental/optional> 16 17int main() 18{ 19#if _LIBCPP_STD_VER > 11 20 using std::experimental::optional; 21 22 optional<int&> opt; 23#else 24#error 25#endif // _LIBCPP_STD_VER > 11 26} 27