--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libcxx/include/__algorithm/in_in_result.h	Wed Nov 09 17:45:10 2022 +0900
@@ -0,0 +1,53 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// 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___ALGORITHM_IN_IN_RESULT_H
+#define _LIBCPP___ALGORITHM_IN_IN_RESULT_H
+
+#include <__concepts/convertible_to.h>
+#include <__config>
+#include <__utility/move.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 17
+
+namespace ranges {
+
+template <class _InIter1, class _InIter2>
+struct in_in_result {
+  _LIBCPP_NO_UNIQUE_ADDRESS _InIter1 in1;
+  _LIBCPP_NO_UNIQUE_ADDRESS _InIter2 in2;
+
+  template <class _InIter3, class _InIter4>
+    requires convertible_to<const _InIter1&, _InIter3> && convertible_to<const _InIter2&, _InIter4>
+   _LIBCPP_HIDE_FROM_ABI constexpr
+   operator in_in_result<_InIter3, _InIter4>() const & {
+    return {in1, in2};
+  }
+
+  template <class _InIter3, class _InIter4>
+    requires convertible_to<_InIter1, _InIter3> && convertible_to<_InIter2, _InIter4>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  operator in_in_result<_InIter3, _InIter4>() && {
+    return {std::move(in1), std::move(in2)};
+  }
+};
+
+} // namespace ranges
+
+#endif // _LIBCPP_STD_VER > 17
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___ALGORITHM_IN_IN_RESULT_H