Fix whitespace, add a couple of tests for [[clang::lifetimebound]] an…

…notations in libc++, and avoid erroring on lifetimebound warnings in libcxx test code

libcxx/include/__expected/expected.h

@@ -722,7 +722,8 @@ class expected : private __expected_base<_Tp, _Err> {
 
   template <class _Up, class... _Args>
     requires is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>
-  _LIBCPP_HIDE_FROM_ABI constexpr _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) noexcept _LIBCPP_LIFETIMEBOUND {
+  _LIBCPP_HIDE_FROM_ABI constexpr _Tp&
+  emplace(initializer_list<_Up> __il, _Args&&... __args) noexcept _LIBCPP_LIFETIMEBOUND {
     this->__destroy();
     this->__construct(in_place, __il, std::forward<_Args>(__args)...);
     return this->__val();

libcxx/include/__tree

@@ -962,7 +962,9 @@ private:
 public:
   _LIBCPP_HIDE_FROM_ABI const size_type& size() const _NOEXCEPT { return __size_; }
   _LIBCPP_HIDE_FROM_ABI value_compare& value_comp() _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return __value_comp_; }
-  _LIBCPP_HIDE_FROM_ABI const value_compare& value_comp() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return __value_comp_; }
+  _LIBCPP_HIDE_FROM_ABI const value_compare& value_comp() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return __value_comp_;
+  }
 
 public:
   _LIBCPP_HIDE_FROM_ABI __node_pointer __root() const _NOEXCEPT {
@@ -995,9 +997,13 @@ public:
   _LIBCPP_HIDE_FROM_ABI ~__tree();
 
   _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return iterator(__begin_node()); }
-  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_iterator(__begin_node()); }
+  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return const_iterator(__begin_node());
+  }
   _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return iterator(__end_node()); }
-  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_iterator(__end_node()); }
+  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return const_iterator(__end_node());
+  }
 
   _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
     return std::min<size_type>(__node_traits::max_size(__node_alloc()), numeric_limits<difference_type >::max());

libcxx/include/deque

@@ -733,14 +733,22 @@ public:
   }
 
   _LIBCPP_HIDE_FROM_ABI reverse_iterator rbegin() _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return reverse_iterator(end()); }
-  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_reverse_iterator(end()); }
+  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return const_reverse_iterator(end());
+  }
   _LIBCPP_HIDE_FROM_ABI reverse_iterator rend() _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return reverse_iterator(begin()); }
-  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_reverse_iterator(begin()); }
+  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return const_reverse_iterator(begin());
+  }
 
   _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return begin(); }
   _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return end(); }
-  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_reverse_iterator(end()); }
-  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_reverse_iterator(begin()); }
+  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return const_reverse_iterator(end());
+  }
+  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return const_reverse_iterator(begin());
+  }
 
   // capacity:
   _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __size(); }
@@ -811,7 +819,8 @@ public:
   _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, _InputIter __f, _InputIter __l) _LIBCPP_LIFETIMEBOUND;
   template <class _ForwardIterator,
             __enable_if_t<__has_exactly_forward_iterator_category<_ForwardIterator>::value, int> = 0>
-  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, _ForwardIterator __f, _ForwardIterator __l) _LIBCPP_LIFETIMEBOUND;
+  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, _ForwardIterator __f, _ForwardIterator __l)
+      _LIBCPP_LIFETIMEBOUND;
   template <class _BiIter, __enable_if_t<__has_bidirectional_iterator_category<_BiIter>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, _BiIter __f, _BiIter __l) _LIBCPP_LIFETIMEBOUND;
 

libcxx/include/ext/hash_map

@@ -519,7 +519,9 @@ public:
   _LIBCPP_HIDE_FROM_ABI std::pair<iterator, bool> insert(const value_type& __x) _LIBCPP_LIFETIMEBOUND {
     return __table_.__insert_unique(__x);
   }
-  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator, const value_type& __x) _LIBCPP_LIFETIMEBOUND { return insert(__x).first; }
+  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator, const value_type& __x) _LIBCPP_LIFETIMEBOUND {
+    return insert(__x).first;
+  }
   template <class _InputIterator>
   _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __first, _InputIterator __last);
 
@@ -536,12 +538,15 @@ public:
   _LIBCPP_HIDE_FROM_ABI key_equal key_eq() const { return __table_.key_eq().key_eq(); }
 
   _LIBCPP_HIDE_FROM_ABI iterator find(const key_type& __k) _LIBCPP_LIFETIMEBOUND { return __table_.find(__k); }
-  _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const _LIBCPP_LIFETIMEBOUND { return __table_.find(__k); }
+  _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const _LIBCPP_LIFETIMEBOUND {
+    return __table_.find(__k);
+  }
   _LIBCPP_HIDE_FROM_ABI size_type count(const key_type& __k) const { return __table_.__count_unique(__k); }
   _LIBCPP_HIDE_FROM_ABI std::pair<iterator, iterator> equal_range(const key_type& __k) _LIBCPP_LIFETIMEBOUND {
     return __table_.__equal_range_unique(__k);
   }
-  _LIBCPP_HIDE_FROM_ABI std::pair<const_iterator, const_iterator> equal_range(const key_type& __k) const _LIBCPP_LIFETIMEBOUND {
+  _LIBCPP_HIDE_FROM_ABI std::pair<const_iterator, const_iterator>
+  equal_range(const key_type& __k) const _LIBCPP_LIFETIMEBOUND {
     return __table_.__equal_range_unique(__k);
   }
 
@@ -741,8 +746,12 @@ public:
   _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _LIBCPP_LIFETIMEBOUND { return __table_.begin(); }
   _LIBCPP_HIDE_FROM_ABI const_iterator end() const _LIBCPP_LIFETIMEBOUND { return __table_.end(); }
 
-  _LIBCPP_HIDE_FROM_ABI iterator insert(const value_type& __x) _LIBCPP_LIFETIMEBOUND { return __table_.__insert_multi(__x); }
-  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator, const value_type& __x) _LIBCPP_LIFETIMEBOUND { return insert(__x); }
+  _LIBCPP_HIDE_FROM_ABI iterator insert(const value_type& __x) _LIBCPP_LIFETIMEBOUND {
+    return __table_.__insert_multi(__x);
+  }
+  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator, const value_type& __x) _LIBCPP_LIFETIMEBOUND {
+    return insert(__x);
+  }
   template <class _InputIterator>
   _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __first, _InputIterator __last);
 
@@ -759,12 +768,15 @@ public:
   _LIBCPP_HIDE_FROM_ABI key_equal key_eq() const { return __table_.key_eq().key_eq(); }
 
   _LIBCPP_HIDE_FROM_ABI iterator find(const key_type& __k) _LIBCPP_LIFETIMEBOUND { return __table_.find(__k); }
-  _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const _LIBCPP_LIFETIMEBOUND { return __table_.find(__k); }
+  _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const _LIBCPP_LIFETIMEBOUND {
+    return __table_.find(__k);
+  }
   _LIBCPP_HIDE_FROM_ABI size_type count(const key_type& __k) const { return __table_.__count_multi(__k); }
   _LIBCPP_HIDE_FROM_ABI std::pair<iterator, iterator> equal_range(const key_type& __k) _LIBCPP_LIFETIMEBOUND {
     return __table_.__equal_range_multi(__k);
   }
-  _LIBCPP_HIDE_FROM_ABI std::pair<const_iterator, const_iterator> equal_range(const key_type& __k) const _LIBCPP_LIFETIMEBOUND {
+  _LIBCPP_HIDE_FROM_ABI std::pair<const_iterator, const_iterator>
+  equal_range(const key_type& __k) const _LIBCPP_LIFETIMEBOUND {
     return __table_.__equal_range_multi(__k);
   }
 

libcxx/include/ext/hash_set

@@ -278,7 +278,9 @@ public:
   _LIBCPP_HIDE_FROM_ABI std::pair<iterator, bool> insert(const value_type& __x) _LIBCPP_LIFETIMEBOUND {
     return __table_.__insert_unique(__x);
   }
-  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator, const value_type& __x) _LIBCPP_LIFETIMEBOUND { return insert(__x).first; }
+  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator, const value_type& __x) _LIBCPP_LIFETIMEBOUND {
+    return insert(__x).first;
+  }
   template <class _InputIterator>
   _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __first, _InputIterator __last);
 
@@ -293,12 +295,15 @@ public:
   _LIBCPP_HIDE_FROM_ABI key_equal key_eq() const { return __table_.key_eq(); }
 
   _LIBCPP_HIDE_FROM_ABI iterator find(const key_type& __k) _LIBCPP_LIFETIMEBOUND { return __table_.find(__k); }
-  _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const _LIBCPP_LIFETIMEBOUND { return __table_.find(__k); }
+  _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const _LIBCPP_LIFETIMEBOUND {
+    return __table_.find(__k);
+  }
   _LIBCPP_HIDE_FROM_ABI size_type count(const key_type& __k) const { return __table_.__count_unique(__k); }
   _LIBCPP_HIDE_FROM_ABI std::pair<iterator, iterator> equal_range(const key_type& __k) _LIBCPP_LIFETIMEBOUND {
     return __table_.__equal_range_unique(__k);
   }
-  _LIBCPP_HIDE_FROM_ABI std::pair<const_iterator, const_iterator> equal_range(const key_type& __k) const _LIBCPP_LIFETIMEBOUND {
+  _LIBCPP_HIDE_FROM_ABI std::pair<const_iterator, const_iterator>
+  equal_range(const key_type& __k) const _LIBCPP_LIFETIMEBOUND {
     return __table_.__equal_range_unique(__k);
   }
 
@@ -455,8 +460,12 @@ public:
   _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _LIBCPP_LIFETIMEBOUND { return __table_.begin(); }
   _LIBCPP_HIDE_FROM_ABI const_iterator end() const _LIBCPP_LIFETIMEBOUND { return __table_.end(); }
 
-  _LIBCPP_HIDE_FROM_ABI iterator insert(const value_type& __x) _LIBCPP_LIFETIMEBOUND { return __table_.__insert_multi(__x); }
-  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator, const value_type& __x) _LIBCPP_LIFETIMEBOUND { return insert(__x); }
+  _LIBCPP_HIDE_FROM_ABI iterator insert(const value_type& __x) _LIBCPP_LIFETIMEBOUND {
+    return __table_.__insert_multi(__x);
+  }
+  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator, const value_type& __x) _LIBCPP_LIFETIMEBOUND {
+    return insert(__x);
+  }
   template <class _InputIterator>
   _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __first, _InputIterator __last);
 
@@ -471,12 +480,15 @@ public:
   _LIBCPP_HIDE_FROM_ABI key_equal key_eq() const { return __table_.key_eq(); }
 
   _LIBCPP_HIDE_FROM_ABI iterator find(const key_type& __k) _LIBCPP_LIFETIMEBOUND { return __table_.find(__k); }
-  _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const _LIBCPP_LIFETIMEBOUND { return __table_.find(__k); }
+  _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const _LIBCPP_LIFETIMEBOUND {
+    return __table_.find(__k);
+  }
   _LIBCPP_HIDE_FROM_ABI size_type count(const key_type& __k) const { return __table_.__count_multi(__k); }
   _LIBCPP_HIDE_FROM_ABI std::pair<iterator, iterator> equal_range(const key_type& __k) _LIBCPP_LIFETIMEBOUND {
     return __table_.__equal_range_multi(__k);
   }
-  _LIBCPP_HIDE_FROM_ABI std::pair<const_iterator, const_iterator> equal_range(const key_type& __k) const _LIBCPP_LIFETIMEBOUND {
+  _LIBCPP_HIDE_FROM_ABI std::pair<const_iterator, const_iterator>
+  equal_range(const key_type& __k) const _LIBCPP_LIFETIMEBOUND {
     return __table_.__equal_range_multi(__k);
   }
 

libcxx/include/forward_list

@@ -740,7 +740,9 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT { return allocator_type(__base::__alloc()); }
 
-  _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return iterator(__base::__before_begin()->__next_); }
+  _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return iterator(__base::__before_begin()->__next_);
+  }
   _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
     return const_iterator(__base::__before_begin()->__next_);
   }
@@ -752,7 +754,9 @@ public:
   }
   _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_iterator(nullptr); }
 
-  _LIBCPP_HIDE_FROM_ABI iterator before_begin() _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return iterator(__base::__before_begin()); }
+  _LIBCPP_HIDE_FROM_ABI iterator before_begin() _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return iterator(__base::__before_begin());
+  }
   _LIBCPP_HIDE_FROM_ABI const_iterator before_begin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
     return const_iterator(__base::__before_begin());
   }
@@ -767,8 +771,12 @@ public:
     return std::min<size_type>(__node_traits::max_size(__base::__alloc()), numeric_limits<difference_type>::max());
   }
 
-  _LIBCPP_HIDE_FROM_ABI reference front() _LIBCPP_LIFETIMEBOUND { return __base::__before_begin()->__next_->__get_value(); }
-  _LIBCPP_HIDE_FROM_ABI const_reference front() const _LIBCPP_LIFETIMEBOUND { return __base::__before_begin()->__next_->__get_value(); }
+  _LIBCPP_HIDE_FROM_ABI reference front() _LIBCPP_LIFETIMEBOUND {
+    return __base::__before_begin()->__next_->__get_value();
+  }
+  _LIBCPP_HIDE_FROM_ABI const_reference front() const _LIBCPP_LIFETIMEBOUND {
+    return __base::__before_begin()->__next_->__get_value();
+  }
 
 #ifndef _LIBCPP_CXX03_LANG
 #  if _LIBCPP_STD_VER >= 17
@@ -796,14 +804,17 @@ public:
   _LIBCPP_HIDE_FROM_ABI iterator emplace_after(const_iterator __p, _Args&&... __args) _LIBCPP_LIFETIMEBOUND;
 
   _LIBCPP_HIDE_FROM_ABI iterator insert_after(const_iterator __p, value_type&& __v) _LIBCPP_LIFETIMEBOUND;
-  _LIBCPP_HIDE_FROM_ABI iterator insert_after(const_iterator __p, initializer_list<value_type> __il) _LIBCPP_LIFETIMEBOUND {
+  _LIBCPP_HIDE_FROM_ABI iterator insert_after(const_iterator __p, initializer_list<value_type> __il)
+      _LIBCPP_LIFETIMEBOUND {
     return insert_after(__p, __il.begin(), __il.end());
   }
 #endif // _LIBCPP_CXX03_LANG
   _LIBCPP_HIDE_FROM_ABI iterator insert_after(const_iterator __p, const value_type& __v) _LIBCPP_LIFETIMEBOUND;
-  _LIBCPP_HIDE_FROM_ABI iterator insert_after(const_iterator __p, size_type __n, const value_type& __v) _LIBCPP_LIFETIMEBOUND;
+  _LIBCPP_HIDE_FROM_ABI iterator insert_after(const_iterator __p, size_type __n, const value_type& __v)
+      _LIBCPP_LIFETIMEBOUND;
   template <class _InputIterator, __enable_if_t<__has_input_iterator_category<_InputIterator>::value, int> = 0>
-  _LIBCPP_HIDE_FROM_ABI iterator insert_after(const_iterator __p, _InputIterator __f, _InputIterator __l) _LIBCPP_LIFETIMEBOUND;
+  _LIBCPP_HIDE_FROM_ABI iterator insert_after(const_iterator __p, _InputIterator __f, _InputIterator __l)
+      _LIBCPP_LIFETIMEBOUND;
 
 #if _LIBCPP_STD_VER >= 23
   template <_ContainerCompatibleRange<_Tp> _Range>

libcxx/include/list

@@ -525,9 +525,13 @@ protected:
   _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT { return __sz() == 0; }
 
   _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return iterator(__end_.__next_); }
-  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_iterator(__end_.__next_); }
+  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return const_iterator(__end_.__next_);
+  }
   _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return iterator(__end_as_link()); }
-  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_iterator(__end_as_link()); }
+  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return const_iterator(__end_as_link());
+  }
 
   _LIBCPP_HIDE_FROM_ABI void swap(__list_imp& __c)
 #if _LIBCPP_STD_VER >= 14
@@ -772,11 +776,19 @@ public:
   _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return __base::end(); }
 
   _LIBCPP_HIDE_FROM_ABI reverse_iterator rbegin() _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return reverse_iterator(end()); }
-  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_reverse_iterator(end()); }
+  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return const_reverse_iterator(end());
+  }
   _LIBCPP_HIDE_FROM_ABI reverse_iterator rend() _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return reverse_iterator(begin()); }
-  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_reverse_iterator(begin()); }
-  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_reverse_iterator(end()); }
-  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND { return const_reverse_iterator(begin()); }
+  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return const_reverse_iterator(begin());
+  }
+  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return const_reverse_iterator(end());
+  }
+  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT _LIBCPP_LIFETIMEBOUND {
+    return const_reverse_iterator(begin());
+  }
 
   _LIBCPP_HIDE_FROM_ABI reference front() _LIBCPP_LIFETIMEBOUND {
     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::front called on empty list");