Upd libc++ to 18 Jun 2022 ff3989e6ae740a9b3adaad0e2bf7691ffd6dad12

```
[libc++] Add Implemented Papers section
[libc++] Enable -Wweak-vtables
[libc++] Make sure we install libc++abi headers on Apple
[libc++] Don't force -O2 when building the benchmarks
[libc++] Mark standard-mandated includes as such
[libc++] Implement std::boyer_moore{, _horspool}_searcher
[libc++] Unwrap reverse_iterator<reverse_iterator<Iter>> in __unwrap_iter
[libc++] Simplify __config a bit
[libc++][ranges] Implement `ranges::sort`.
[libc++] Remove now-unused experimental/filesystem config file
[libc++] Robust against C++20-hostile iterators
[libc++] Implement ranges::lexicographical_compare
[libc++] Removes unneeded <iterator> includes.
[libcxx] Fix allocator<void>::pointer in C++20 with removed members
[libcxx] Remove extraneous '---' lines in .clang-format files
[libc++][NFCI] span: replace enable_if with concepts
[libc++] Find a clang-format everybody is happy with
[libc++] Use explicit module cache path in tests
[libc++] Remove macros for IBM compiler
```

1 files changed, 18 insertions, 4 deletions

diff --git a/contrib/libs/cxxsupp/libcxx/include/__algorithm/unwrap_iter.h b/contrib/libs/cxxsupp/libcxx/include/__algorithm/unwrap_iter.h
index be33194164..7d1807b7bb 100644
--- a/contrib/libs/cxxsupp/libcxx/include/__algorithm/unwrap_iter.h
+++ b/contrib/libs/cxxsupp/libcxx/include/__algorithm/unwrap_iter.h
@@ -63,6 +63,22 @@ __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_CONSTEXPR
 _OrigIter __rewrap_iter(_OrigIter, _OrigIter __result)
@@ -70,13 +86,11 @@ _OrigIter __rewrap_iter(_OrigIter, _OrigIter __result)
     return __result;
 }
 
-template<class _OrigIter, class _UnwrappedIter>
+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