1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___FWD_OPTIONAL_H
10#define _LIBCPP___FWD_OPTIONAL_H
11
12#include <__config>
13
14#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
15# pragma GCC system_header
16#endif
17
18_LIBCPP_PUSH_MACROS
19#include <__undef_macros>
20
21#if _LIBCPP_STD_VER >= 17
22
23_LIBCPP_BEGIN_NAMESPACE_STD
24
25template <class _Tp>
26class optional;
27
28# if _LIBCPP_STD_VER >= 26
29template <class _Tp>
30class optional<_Tp&>;
31# endif
32
33template <class _Tp>
34optional(_Tp) -> optional<_Tp>;
35
36_LIBCPP_END_NAMESPACE_STD
37
38#endif // _LIBCPP_STD_VER >= 17
39
40_LIBCPP_POP_MACROS
41
42#endif // _LIBCPP___FWD_OPTIONAL_H
43