Upgrade to 2022-era LLVM LIBCXX

third_party/libcxx/__iterator/projected.h

@@ -0,0 +1,41 @@
+// -*- 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___ITERATOR_PROJECTED_H
+#define _LIBCPP___ITERATOR_PROJECTED_H
+
+#include <__config>
+#include <__iterator/concepts.h>
+#include <__iterator/incrementable_traits.h>
+#include <__type_traits/remove_cvref.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 20
+
+template<indirectly_readable _It, indirectly_regular_unary_invocable<_It> _Proj>
+struct projected {
+  using value_type = remove_cvref_t<indirect_result_t<_Proj&, _It>>;
+  indirect_result_t<_Proj&, _It> operator*() const; // not defined
+};
+
+template<weakly_incrementable _It, class _Proj>
+struct incrementable_traits<projected<_It, _Proj>> {
+  using difference_type = iter_difference_t<_It>;
+};
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___ITERATOR_PROJECTED_H