1// -*- C++ -*- 2//===----------------------------------------------------------------------===// 3// 4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5// See https://llvm.org/LICENSE.txt for license information. 6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7// 8//===----------------------------------------------------------------------===// 9 10#ifndef _LIBCPP___ITERATOR_UNREACHABLE_SENTINEL_H 11#define _LIBCPP___ITERATOR_UNREACHABLE_SENTINEL_H 12 13#include <__config> 14#include <__iterator/concepts.h> 15 16#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 17# pragma GCC system_header 18#endif 19 20_LIBCPP_BEGIN_NAMESPACE_STD 21 22#if _LIBCPP_STD_VER >= 20 23 24struct unreachable_sentinel_t { 25 template <weakly_incrementable _Iter> 26 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(unreachable_sentinel_t, const _Iter&) noexcept { 27 return false; 28 } 29}; 30 31inline constexpr unreachable_sentinel_t unreachable_sentinel{}; 32 33#endif // _LIBCPP_STD_VER >= 20 34 35_LIBCPP_END_NAMESPACE_STD 36 37#endif // _LIBCPP___ITERATOR_UNREACHABLE_SENTINEL_H 38