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 24 struct 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 31 inline 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