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// A program that necessitates the instantiation of template optional for
1301afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant// (possibly cv-qualified) null_opt_t is ill-formed.
1401afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant
150cdbe6048173c1f05628dbc85430acf191a3e173Marshall Clow#include <experimental/optional>
1601afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant
1701afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnantint main()
1801afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant{
1901afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant#if _LIBCPP_STD_VER > 11
200cdbe6048173c1f05628dbc85430acf191a3e173Marshall Clow    using std::experimental::optional;
210cdbe6048173c1f05628dbc85430acf191a3e173Marshall Clow    using std::experimental::nullopt_t;
220cdbe6048173c1f05628dbc85430acf191a3e173Marshall Clow    using std::experimental::nullopt;
230cdbe6048173c1f05628dbc85430acf191a3e173Marshall Clow
240cdbe6048173c1f05628dbc85430acf191a3e173Marshall Clow    optional<nullopt_t> opt;
2501afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant#else
2601afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant#error
2701afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant#endif  // _LIBCPP_STD_VER > 11
2801afa5c6e407e985d9643707d7b7ab1384bd9317Howard Hinnant}
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