101afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant//===----------------------------------------------------------------------===//
201afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant//
301afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant//                     The LLVM Compiler Infrastructure
401afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant//
501afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant// This file is dual licensed under the MIT and the University of Illinois Open
601afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant// Source Licenses. See LICENSE.TXT for details.
701afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant//
801afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant//===----------------------------------------------------------------------===//
901afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant
1001afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant// <optional>
1101afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant
1201afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant// constexpr const T& optional<T>::value() const;
1301afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant
140cdbe6048173c1f05628dbc85430acf191a3e173Marshall Clow#include <experimental/optional>
1501afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant#include <type_traits>
1601afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant#include <cassert>
1701afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant
1801afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant#if _LIBCPP_STD_VER > 11
1901afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant
200cdbe6048173c1f05628dbc85430acf191a3e173Marshall Clowusing std::experimental::optional;
210cdbe6048173c1f05628dbc85430acf191a3e173Marshall Clow
2201afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnantstruct X
2301afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant{
2401afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant    constexpr int test() const {return 3;}
2501afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant    int test() {return 4;}
2601afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant};
2701afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant
2801afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant#endif  // _LIBCPP_STD_VER > 11
2901afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant
3001afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnantint main()
3101afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant{
3201afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant#if _LIBCPP_STD_VER > 11
3301afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant    {
340cdbe6048173c1f05628dbc85430acf191a3e173Marshall Clow        constexpr optional<X> opt;
3501afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant        static_assert(opt.value().test() == 3, "");
3601afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant    }
3701afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant#else
3801afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant#error
3901afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant#endif  // _LIBCPP_STD_VER > 11
4001afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant}
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