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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___COMPARE_SYNTH_THREE_WAY_H
#define _LIBCPP___COMPARE_SYNTH_THREE_WAY_H
#include <__compare/ordering.h>
#include <__compare/three_way_comparable.h>
#include <__concepts/boolean_testable.h>
#include <__config>
#include <__utility/declval.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER > 17
// [expos.only.func]
_LIBCPP_HIDE_FROM_ABI inline constexpr auto __synth_three_way =
[]<class _Tp, class _Up>(const _Tp& __t, const _Up& __u)
requires requires {
{ __t < __u } -> __boolean_testable;
{ __u < __t } -> __boolean_testable;
}
{
if constexpr (three_way_comparable_with<_Tp, _Up>) {
return __t <=> __u;
} else {
if (__t < __u) return weak_ordering::less;
if (__u < __t) return weak_ordering::greater;
return weak_ordering::equivalent;
}
};
template <class _Tp, class _Up = _Tp>
using __synth_three_way_result = decltype(std::__synth_three_way(std::declval<_Tp&>(), std::declval<_Up&>()));
#endif // _LIBCPP_STD_VER > 17
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___COMPARE_SYNTH_THREE_WAY_H
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