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___COMPARE_COMPARE_THREE_WAY_RESULT_H 10 #define _LIBCPP___COMPARE_COMPARE_THREE_WAY_RESULT_H 11 12 #include <__config> 13 #include <__type_traits/make_const_lvalue_ref.h> 14 #include <__utility/declval.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 template <class, class, class> 25 struct _LIBCPP_HIDE_FROM_ABI __compare_three_way_result {}; 26 27 template <class _Tp, class _Up> 28 struct _LIBCPP_HIDE_FROM_ABI __compare_three_way_result< 29 _Tp, 30 _Up, 31 decltype(std::declval<__make_const_lvalue_ref<_Tp>>() <=> std::declval<__make_const_lvalue_ref<_Up>>(), void())> { 32 using type = decltype(std::declval<__make_const_lvalue_ref<_Tp>>() <=> std::declval<__make_const_lvalue_ref<_Up>>()); 33 }; 34 35 template <class _Tp, class _Up = _Tp> 36 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_NO_SPECIALIZATIONS compare_three_way_result 37 : __compare_three_way_result<_Tp, _Up, void> {}; 38 39 template <class _Tp, class _Up = _Tp> 40 using compare_three_way_result_t = typename compare_three_way_result<_Tp, _Up>::type; 41 42 #endif // _LIBCPP_STD_VER >= 20 43 44 _LIBCPP_END_NAMESPACE_STD 45 46 #endif // _LIBCPP___COMPARE_COMPARE_THREE_WAY_RESULT_H 47