From 145449b1e420787bb99721a429341fa6be3adfb6 Mon Sep 17 00:00:00 2001
From: Dimitry Andric <dim@FreeBSD.org>
Date: Sun, 3 Jul 2022 16:10:23 +0200
Subject: Vendor import of llvm-project main
 llvmorg-15-init-15358-g53dc0f107877.

---
 libcxx/include/__algorithm/unwrap_iter.h | 34 ++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

(limited to 'libcxx/include/__algorithm/unwrap_iter.h')

diff --git a/libcxx/include/__algorithm/unwrap_iter.h b/libcxx/include/__algorithm/unwrap_iter.h
index 35765330bb7f..7d1807b7bbf9 100644
--- a/libcxx/include/__algorithm/unwrap_iter.h
+++ b/libcxx/include/__algorithm/unwrap_iter.h
@@ -10,12 +10,12 @@
 #define _LIBCPP___ALGORITHM_UNWRAP_ITER_H
 
 #include <__config>
+#include <__iterator/iterator_traits.h>
 #include <__memory/pointer_traits.h>
-#include <iterator>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#pragma GCC system_header
+#  pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
@@ -43,7 +43,7 @@ struct __unwrap_iter_impl {
     }
 };
 
-#if _LIBCPP_DEBUG_LEVEL < 2
+#ifndef _LIBCPP_ENABLE_DEBUG_MODE
 
 template <class _Iter>
 struct __unwrap_iter_impl<_Iter, true> {
@@ -53,7 +53,7 @@ struct __unwrap_iter_impl<_Iter, true> {
     }
 };
 
-#endif // _LIBCPP_DEBUG_LEVEL < 2
+#endif // !_LIBCPP_ENABLE_DEBUG_MODE
 
 template<class _Iter, class _Impl = __unwrap_iter_impl<_Iter> >
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
@@ -63,20 +63,34 @@ __unwrap_iter(_Iter __i) _NOEXCEPT
     return _Impl::__apply(__i);
 }
 
+template <class _OrigIter, class _UnwrappedIter>
+struct __rewrap_iter_impl {
+  static _LIBCPP_CONSTEXPR _OrigIter __apply(_OrigIter __first, _UnwrappedIter __result) {
+    // Precondition: __result is reachable from __first
+    // Precondition: _OrigIter is a contiguous iterator
+    return __first + (__result - std::__unwrap_iter(__first));
+  }
+};
+
+template <class _OrigIter>
+struct __rewrap_iter_impl<_OrigIter, _OrigIter> {
+  static _LIBCPP_CONSTEXPR _OrigIter __apply(_OrigIter, _OrigIter __result) {
+    return __result;
+  }
+};
+
 template<class _OrigIter>
-_LIBCPP_HIDE_FROM_ABI
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR
 _OrigIter __rewrap_iter(_OrigIter, _OrigIter __result)
 {
     return __result;
 }
 
-template<class _OrigIter, class _UnwrappedIter>
-_LIBCPP_HIDE_FROM_ABI
+template<class _OrigIter, class _UnwrappedIter, class _Impl = __rewrap_iter_impl<_OrigIter, _UnwrappedIter> >
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR
 _OrigIter __rewrap_iter(_OrigIter __first, _UnwrappedIter __result)
 {
-    // Precondition: __result is reachable from __first
-    // Precondition: _OrigIter is a contiguous iterator
-    return __first + (__result - _VSTD::__unwrap_iter(__first));
+  return _Impl::__apply(__first, __result);
 }
 
 _LIBCPP_END_NAMESPACE_STD
-- 
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