[libc++] Remove a bunch of conditionals on _LIBCPP_DEBUG_LEVEL

[ldionne]

Summary

Instead of providing two different constructors for iterators that
support the debug mode, provide a single constructor but leave the
container parameter unused when the debug mode is not enabled.

This allows simplifying all the call sites to unconditionally pass
the container, which removes a bunch of duplication in the container's
implementation.

Note that this patch does add some complexity to std::span, however
that is only because std::span has the ability to use raw pointers
as iterators instead of __wrap_iter. In retrospect, I believe it was
a mistake to provide that capability, and so it will be removed in a
future patch, along with the complexity added by this patch.

[philnik]

libcxx/include/__hash_table

369–370

Maybe add __debug_db_inster_ic()?

[ldionne]

libcxx/include/__hash_table

369–370

Yeah, good idea. I'll do it in a separate patch to ease rebasing D122941, which touches a lot of code.

libcxx/include/__hash_table

#endif // _LIBCPP_DEBUG_LEVEL == 2
     {
         return __x.__node_ == __y.__node_;
     }
     friend _LIBCPP_INLINE_VISIBILITY
     bool operator!=(const __hash_iterator& __x, const __hash_iterator& __y)
         {return !(__x == __y);}
 
 private:
-#if _LIBCPP_DEBUG_LEVEL == 2
     _LIBCPP_INLINE_VISIBILITY
     explicit __hash_iterator(__next_pointer __node, const void* __c) _NOEXCEPT
         : __node_(__node)
         {
+            (void)__c;
+#if _LIBCPP_DEBUG_LEVEL == 2
             __get_db()->__insert_ic(this, __c);
-        }
-#else
-    _LIBCPP_INLINE_VISIBILITY
-    explicit __hash_iterator(__next_pointer __node) _NOEXCEPT
-        : __node_(__node)
-        {}
 #endif
+        }
     template <class, class, class, class> friend class __hash_table;
     template <class> friend class _LIBCPP_TEMPLATE_VIS __hash_const_iterator;
     template <class> friend class _LIBCPP_TEMPLATE_VIS __hash_map_iterator;
     template <class, class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS unordered_map;
     template <class, class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS unordered_multimap;
 };
 
 template <class _NodePtr>
#endif // _LIBCPP_DEBUG_LEVEL == 2
     {
         return __x.__node_ == __y.__node_;
     }
     friend _LIBCPP_INLINE_VISIBILITY
     bool operator!=(const __hash_const_iterator& __x, const __hash_const_iterator& __y)
         {return !(__x == __y);}
 
 private:
-#if _LIBCPP_DEBUG_LEVEL == 2
     _LIBCPP_INLINE_VISIBILITY
     explicit __hash_const_iterator(__next_pointer __node, const void* __c) _NOEXCEPT
         : __node_(__node)
         {
+            (void)__c;
+#if _LIBCPP_DEBUG_LEVEL == 2
             __get_db()->__insert_ic(this, __c);
-        }
-#else
-    _LIBCPP_INLINE_VISIBILITY
-    explicit __hash_const_iterator(__next_pointer __node) _NOEXCEPT
-        : __node_(__node)
-        {}
 #endif
+        }
     template <class, class, class, class> friend class __hash_table;
     template <class> friend class _LIBCPP_TEMPLATE_VIS __hash_map_const_iterator;
     template <class, class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS unordered_map;
     template <class, class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS unordered_multimap;
 };
 
 template <class _NodePtr>
 class _LIBCPP_TEMPLATE_VIS __hash_local_iterator
#endif // _LIBCPP_DEBUG_LEVEL == 2
     {
         return __x.__node_ == __y.__node_;
     }
     friend _LIBCPP_INLINE_VISIBILITY
     bool operator!=(const __hash_local_iterator& __x, const __hash_local_iterator& __y)
         {return !(__x == __y);}
 
 private:
-#if _LIBCPP_DEBUG_LEVEL == 2
     _LIBCPP_INLINE_VISIBILITY
     explicit __hash_local_iterator(__next_pointer __node, size_t __bucket,
                                    size_t __bucket_count, const void* __c) _NOEXCEPT
         : __node_(__node),
           __bucket_(__bucket),
           __bucket_count_(__bucket_count)
         {
+            (void)__c;
+#if _LIBCPP_DEBUG_LEVEL == 2
             __get_db()->__insert_ic(this, __c);
+#endif
             if (__node_ != nullptr)
                 __node_ = __node_->__next_;
         }
-#else
-    _LIBCPP_INLINE_VISIBILITY
-    explicit __hash_local_iterator(__next_pointer __node, size_t __bucket,
-                                   size_t __bucket_count) _NOEXCEPT
-        : __node_(__node),
-          __bucket_(__bucket),
-          __bucket_count_(__bucket_count)
-        {
-            if (__node_ != nullptr)
-                __node_ = __node_->__next_;
-        }
-#endif
     template <class, class, class, class> friend class __hash_table;
     template <class> friend class _LIBCPP_TEMPLATE_VIS __hash_const_local_iterator;
     template <class> friend class _LIBCPP_TEMPLATE_VIS __hash_map_iterator;
 };
 
 template <class _ConstNodePtr>
 class _LIBCPP_TEMPLATE_VIS __hash_const_local_iterator
 {
#endif // _LIBCPP_DEBUG_LEVEL == 2
     {
         return __x.__node_ == __y.__node_;
     }
     friend _LIBCPP_INLINE_VISIBILITY
     bool operator!=(const __hash_const_local_iterator& __x, const __hash_const_local_iterator& __y)
         {return !(__x == __y);}
 
 private:
-#if _LIBCPP_DEBUG_LEVEL == 2
     _LIBCPP_INLINE_VISIBILITY
     explicit __hash_const_local_iterator(__next_pointer __node_ptr, size_t __bucket,
                                          size_t __bucket_count, const void* __c) _NOEXCEPT
         : __node_(__node_ptr),
           __bucket_(__bucket),
           __bucket_count_(__bucket_count)
         {
+            (void)__c;
+#if _LIBCPP_DEBUG_LEVEL == 2
             __get_db()->__insert_ic(this, __c);
+#endif
             if (__node_ != nullptr)
                 __node_ = __node_->__next_;
         }
-#else
-    _LIBCPP_INLINE_VISIBILITY
-    explicit __hash_const_local_iterator(__next_pointer __node_ptr, size_t __bucket,
-                                         size_t __bucket_count) _NOEXCEPT
-        : __node_(__node_ptr),
-          __bucket_(__bucket),
-          __bucket_count_(__bucket_count)
-        {
-            if (__node_ != nullptr)
-                __node_ = __node_->__next_;
-        }
-#endif
     template <class, class, class, class> friend class __hash_table;
     template <class> friend class _LIBCPP_TEMPLATE_VIS __hash_map_const_iterator;
 };
 
 template <class _Alloc>
 class __bucket_list_deallocator
 {
     typedef _Alloc                                          allocator_type;
#endif
     }
 
     _LIBCPP_INLINE_VISIBILITY
     local_iterator
     begin(size_type __n)
     {
         _LIBCPP_ASSERT(__n < bucket_count(),
             "unordered container::begin(n) called with n >= bucket_count()");
-#if _LIBCPP_DEBUG_LEVEL == 2
         return local_iterator(__bucket_list_[__n], __n, bucket_count(), this);
-#else
-        return local_iterator(__bucket_list_[__n], __n, bucket_count());
-#endif
     }
 
     _LIBCPP_INLINE_VISIBILITY
     local_iterator
     end(size_type __n)
     {
         _LIBCPP_ASSERT(__n < bucket_count(),
             "unordered container::end(n) called with n >= bucket_count()");
-#if _LIBCPP_DEBUG_LEVEL == 2
         return local_iterator(nullptr, __n, bucket_count(), this);
-#else
-        return local_iterator(nullptr, __n, bucket_count());
-#endif
     }
 
     _LIBCPP_INLINE_VISIBILITY
     const_local_iterator
     cbegin(size_type __n) const
     {
         _LIBCPP_ASSERT(__n < bucket_count(),
             "unordered container::cbegin(n) called with n >= bucket_count()");
-#if _LIBCPP_DEBUG_LEVEL == 2
         return const_local_iterator(__bucket_list_[__n], __n, bucket_count(), this);
-#else
-        return const_local_iterator(__bucket_list_[__n], __n, bucket_count());
-#endif
     }
 
     _LIBCPP_INLINE_VISIBILITY
     const_local_iterator
     cend(size_type __n) const
     {
         _LIBCPP_ASSERT(__n < bucket_count(),
             "unordered container::cend(n) called with n >= bucket_count()");
-#if _LIBCPP_DEBUG_LEVEL == 2
         return const_local_iterator(nullptr, __n, bucket_count(), this);
-#else
-        return const_local_iterator(nullptr, __n, bucket_count());
-#endif
     }
 
 #if _LIBCPP_DEBUG_LEVEL == 2
 
     bool __dereferenceable(const const_iterator* __i) const;
     bool __decrementable(const const_iterator* __i) const;
     bool __addable(const const_iterator* __i, ptrdiff_t __n) const;
     bool __subscriptable(const const_iterator* __i, ptrdiff_t __n) const;
for (; __first != __last; ++__first)
         __insert_multi(_NodeTypes::__get_value(*__first));
 }
 
 template <class _Tp, class _Hash, class _Equal, class _Alloc>
 inline
 typename __hash_table<_Tp, _Hash, _Equal, _Alloc>::iterator
 __hash_table<_Tp, _Hash, _Equal, _Alloc>::begin() _NOEXCEPT
 {
-#if _LIBCPP_DEBUG_LEVEL == 2
     return iterator(__p1_.first().__next_, this);
-#else
-    return iterator(__p1_.first().__next_);
-#endif
 }
 
 template <class _Tp, class _Hash, class _Equal, class _Alloc>
 inline
 typename __hash_table<_Tp, _Hash, _Equal, _Alloc>::iterator
 __hash_table<_Tp, _Hash, _Equal, _Alloc>::end() _NOEXCEPT
 {
-#if _LIBCPP_DEBUG_LEVEL == 2
     return iterator(nullptr, this);
-#else
-    return iterator(nullptr);
-#endif
 }
 
 template <class _Tp, class _Hash, class _Equal, class _Alloc>
 inline
 typename __hash_table<_Tp, _Hash, _Equal, _Alloc>::const_iterator
 __hash_table<_Tp, _Hash, _Equal, _Alloc>::begin() const _NOEXCEPT
 {
-#if _LIBCPP_DEBUG_LEVEL == 2
     return const_iterator(__p1_.first().__next_, this);
-#else
-    return const_iterator(__p1_.first().__next_);
-#endif
 }
 
 template <class _Tp, class _Hash, class _Equal, class _Alloc>
 inline
 typename __hash_table<_Tp, _Hash, _Equal, _Alloc>::const_iterator
 __hash_table<_Tp, _Hash, _Equal, _Alloc>::end() const _NOEXCEPT
 {
-#if _LIBCPP_DEBUG_LEVEL == 2
     return const_iterator(nullptr, this);
-#else
-    return const_iterator(nullptr);
-#endif
 }
 
 template <class _Tp, class _Hash, class _Equal, class _Alloc>
 void
 __hash_table<_Tp, _Hash, _Equal, _Alloc>::clear() _NOEXCEPT
 {
     if (size() > 0)
     {
__hash_table<_Tp, _Hash, _Equal, _Alloc>::__node_insert_unique(__node_pointer __nd)
     // Insert the node, unless it already exists in the container.
     bool __inserted = false;
     if (__existing_node == nullptr)
     {
         __node_insert_unique_perform(__nd);
         __existing_node = __nd->__ptr();
         __inserted = true;
     }
-#if _LIBCPP_DEBUG_LEVEL == 2
     return pair<iterator, bool>(iterator(__existing_node, this), __inserted);
-#else
-    return pair<iterator, bool>(iterator(__existing_node), __inserted);
-#endif
 }
 
 // Prepare the container for an insertion of the value __cp_val with the hash
 // __cp_hash. This does a lookup into the container to see if __cp_value is
 // already present, and performs a rehash if necessary. Returns a pointer to the
 // last occurrence of __cp_val in the map.
 //
 // Note that this function does forward exceptions if key_eq() throws, and never

 template <class _Tp, class _Hash, class _Equal, class _Alloc>
 typename __hash_table<_Tp, _Hash, _Equal, _Alloc>::iterator
 __hash_table<_Tp, _Hash, _Equal, _Alloc>::__node_insert_multi(__node_pointer __cp)
 {
     __cp->__hash_ = hash_function()(__cp->__value_);
     __next_pointer __pn = __node_insert_multi_prepare(__cp->__hash(), __cp->__value_);
     __node_insert_multi_perform(__cp, __pn);
 
-#if _LIBCPP_DEBUG_LEVEL == 2
     return iterator(__cp->__ptr(), this);
-#else
-    return iterator(__cp->__ptr());
-#endif
 }
 
 template <class _Tp, class _Hash, class _Equal, class _Alloc>
 typename __hash_table<_Tp, _Hash, _Equal, _Alloc>::iterator
 __hash_table<_Tp, _Hash, _Equal, _Alloc>::__node_insert_multi(
         const_iterator __p, __node_pointer __cp)
 {
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__p)) == this,
if (__p != end() && key_eq()(*__p, __cp->__value_))
         }
         size_t __chash = __constrain_hash(__cp->__hash_, __bc);
         __next_pointer __pp = __bucket_list_[__chash];
         while (__pp->__next_ != __np)
             __pp = __pp->__next_;
         __cp->__next_ = __np;
         __pp->__next_ = static_cast<__next_pointer>(__cp);
         ++size();
-#if _LIBCPP_DEBUG_LEVEL == 2
         return iterator(static_cast<__next_pointer>(__cp), this);
-#else
-        return iterator(static_cast<__next_pointer>(__cp));
-#endif
     }
     return __node_insert_multi(__cp);
 }
 
 
 
 template <class _Tp, class _Hash, class _Equal, class _Alloc>
 template <class _Key, class ..._Args>
if (__bc != 0)
             __pn->__next_ = static_cast<__next_pointer>(__h.get());
         }
         __nd = static_cast<__next_pointer>(__h.release());
         // increment size
         ++size();
         __inserted = true;
     }
 __done:
-#if _LIBCPP_DEBUG_LEVEL == 2
     return pair<iterator, bool>(iterator(__nd, this), __inserted);
-#else
-    return pair<iterator, bool>(iterator(__nd), __inserted);
-#endif
 }
 
 template <class _Tp, class _Hash, class _Equal, class _Alloc>
 template <class... _Args>
 pair<typename __hash_table<_Tp, _Hash, _Equal, _Alloc>::iterator, bool>
 __hash_table<_Tp, _Hash, _Equal, _Alloc>::__emplace_unique_impl(_Args&&... __args)
 {
     __node_holder __h = __construct_node(_VSTD::forward<_Args>(__args)...);
if (__bc != 0)
         {
             for (__nd = __nd->__next_; __nd != nullptr &&
                 (__nd->__hash() == __hash
                   || __constrain_hash(__nd->__hash(), __bc) == __chash);
                                                            __nd = __nd->__next_)
             {
                 if ((__nd->__hash() == __hash)
                     && key_eq()(__nd->__upcast()->__value_, __k))
-#if _LIBCPP_DEBUG_LEVEL == 2
                     return iterator(__nd, this);
-#else
-                    return iterator(__nd);
-#endif
             }
         }
     }
     return end();
 }
 
 template <class _Tp, class _Hash, class _Equal, class _Alloc>
 template <class _Key>
if (__bc != 0)
         {
             for (__nd = __nd->__next_; __nd != nullptr &&
                 (__hash == __nd->__hash()
                     || __constrain_hash(__nd->__hash(), __bc) == __chash);
                                                            __nd = __nd->__next_)
             {
                 if ((__nd->__hash() == __hash)
                     && key_eq()(__nd->__upcast()->__value_, __k))
-#if _LIBCPP_DEBUG_LEVEL == 2
                     return const_iterator(__nd, this);
-#else
-                    return const_iterator(__nd);
-#endif
             }
         }
 
     }
     return end();
 }
 
 template <class _Tp, class _Hash, class _Equal, class _Alloc>

 __hash_table<_Tp, _Hash, _Equal, _Alloc>::erase(const_iterator __p)
 {
     __next_pointer __np = __p.__node_;
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__p)) == this,
                          "unordered container erase(iterator) called with an iterator not"
                          " referring to this container");
     _LIBCPP_ASSERT(__p != end(),
                    "unordered container erase(iterator) called with a non-dereferenceable iterator");
-#if _LIBCPP_DEBUG_LEVEL == 2
     iterator __r(__np, this);
-#else
-    iterator __r(__np);
-#endif
     ++__r;
     remove(__p);
     return __r;
 }
 
 template <class _Tp, class _Hash, class _Equal, class _Alloc>
 typename __hash_table<_Tp, _Hash, _Equal, _Alloc>::iterator
 __hash_table<_Tp, _Hash, _Equal, _Alloc>::erase(const_iterator __first,
                                                 const_iterator __last)
 {
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__first)) == this,
                          "unordered container::erase(iterator, iterator) called with an iterator not"
                          " referring to this container");
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__last)) == this,
                          "unordered container::erase(iterator, iterator) called with an iterator not"
                          " referring to this container");
     for (const_iterator __p = __first; __first != __last; __p = __first)
     {
         ++__first;
         erase(__p);
     }
     __next_pointer __np = __last.__node_;
-#if _LIBCPP_DEBUG_LEVEL == 2
     return iterator (__np, this);
-#else
-    return iterator (__np);
-#endif
 }
 
 template <class _Tp, class _Hash, class _Equal, class _Alloc>
 template <class _Key>
 typename __hash_table<_Tp, _Hash, _Equal, _Alloc>::size_type
 __hash_table<_Tp, _Hash, _Equal, _Alloc>::__erase_unique(const _Key& __k)
 {
     iterator __i = find(__k);

libcxx/include/__iterator/wrap_iter.h

_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11 reference    operator[](difference_type __n) const _NOEXCEPT
         _LIBCPP_DEBUG_ASSERT(__get_const_db()->__subscriptable(this, __n),
                              "Attempted to subscript an iterator outside its valid range");
         return __i[__n];
     }
 
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11 iterator_type base() const _NOEXCEPT {return __i;}
 
 private:
-#if _LIBCPP_DEBUG_LEVEL == 2
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
-    explicit __wrap_iter(const void* __p, iterator_type __x) : __i(__x)
+    explicit __wrap_iter(const void* __p, iterator_type __x) _NOEXCEPT : __i(__x)
     {
+        (void)__p;
+#if _LIBCPP_DEBUG_LEVEL == 2
       if (!__libcpp_is_constant_evaluated())
         __get_db()->__insert_ic(this, __p);
-    }
-#else
-    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
-    explicit __wrap_iter(iterator_type __x) _NOEXCEPT : __i(__x) {}
 #endif
+    }
 
     template <class _Up> friend class __wrap_iter;
     template <class _CharT, class _Traits, class _Alloc> friend class basic_string;
     template <class _Tp, class _Alloc> friend class _LIBCPP_TEMPLATE_VIS vector;
     template <class _Tp, size_t> friend class _LIBCPP_TEMPLATE_VIS span;
 };
 
 template <class _Iter1>

libcxx/include/list

 template <class _Tp, class _VoidPtr>
 class _LIBCPP_TEMPLATE_VIS __list_iterator
 {
     typedef __list_node_pointer_traits<_Tp, _VoidPtr> _NodeTraits;
     typedef typename _NodeTraits::__link_pointer __link_pointer;
 
     __link_pointer __ptr_;
 
-#if _LIBCPP_DEBUG_LEVEL == 2
     _LIBCPP_INLINE_VISIBILITY
     explicit __list_iterator(__link_pointer __p, const void* __c) _NOEXCEPT
         : __ptr_(__p)
     {
+        (void)__c;
+#if _LIBCPP_DEBUG_LEVEL == 2
         __get_db()->__insert_ic(this, __c);
-    }
-#else
-    _LIBCPP_INLINE_VISIBILITY
-    explicit __list_iterator(__link_pointer __p) _NOEXCEPT : __ptr_(__p) {}
 #endif
-
-
+    }
 
     template<class, class> friend class list;
     template<class, class> friend class __list_imp;
     template<class, class> friend class __list_const_iterator;
 public:
     typedef bidirectional_iterator_tag       iterator_category;
     typedef _Tp                              value_type;
     typedef value_type&                      reference;

 template <class _Tp, class _VoidPtr>
 class _LIBCPP_TEMPLATE_VIS __list_const_iterator
 {
     typedef __list_node_pointer_traits<_Tp, _VoidPtr> _NodeTraits;
     typedef typename _NodeTraits::__link_pointer __link_pointer;
 
     __link_pointer __ptr_;
 
-#if _LIBCPP_DEBUG_LEVEL == 2
     _LIBCPP_INLINE_VISIBILITY
     explicit __list_const_iterator(__link_pointer __p, const void* __c) _NOEXCEPT
         : __ptr_(__p)
     {
+        (void)__c;
+#if _LIBCPP_DEBUG_LEVEL == 2
         __get_db()->__insert_ic(this, __c);
-    }
-#else
-    _LIBCPP_INLINE_VISIBILITY
-    explicit __list_const_iterator(__link_pointer __p) _NOEXCEPT : __ptr_(__p) {}
 #endif
+    }
 
     template<class, class> friend class list;
     template<class, class> friend class __list_imp;
 public:
     typedef bidirectional_iterator_tag       iterator_category;
     typedef _Tp                              value_type;
     typedef const value_type&                reference;
     typedef typename __rebind_pointer<_VoidPtr, const value_type>::type pointer;
#endif
     ~__list_imp();
     void clear() _NOEXCEPT;
     _LIBCPP_INLINE_VISIBILITY
     bool empty() const _NOEXCEPT {return __sz() == 0;}
 
     _LIBCPP_INLINE_VISIBILITY
     iterator begin() _NOEXCEPT
     {
-#if _LIBCPP_DEBUG_LEVEL == 2
         return iterator(__end_.__next_, this);
-#else
-        return iterator(__end_.__next_);
-#endif
     }
     _LIBCPP_INLINE_VISIBILITY
     const_iterator begin() const  _NOEXCEPT
     {
-#if _LIBCPP_DEBUG_LEVEL == 2
         return const_iterator(__end_.__next_, this);
-#else
-        return const_iterator(__end_.__next_);
-#endif
     }
     _LIBCPP_INLINE_VISIBILITY
     iterator end() _NOEXCEPT
     {
-#if _LIBCPP_DEBUG_LEVEL == 2
         return iterator(__end_as_link(), this);
-#else
-        return iterator(__end_as_link());
-#endif
     }
     _LIBCPP_INLINE_VISIBILITY
     const_iterator end() const _NOEXCEPT
     {
-#if _LIBCPP_DEBUG_LEVEL == 2
         return const_iterator(__end_as_link(), this);
-#else
-        return const_iterator(__end_as_link());
-#endif
     }
 
     void swap(__list_imp& __c)
 #if _LIBCPP_STD_VER >= 14
         _NOEXCEPT;
 #else
         _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
                     __is_nothrow_swappable<allocator_type>::value);

 {
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__p)) == this,
                          "list::insert(iterator, x) called with an iterator not referring to this list");
     __node_allocator& __na = base::__node_alloc();
     __hold_pointer __hold = __allocate_node(__na);
     __node_alloc_traits::construct(__na, _VSTD::addressof(__hold->__value_), __x);
     __link_nodes(__p.__ptr_, __hold->__as_link(), __hold->__as_link());
     ++base::__sz();
-#if _LIBCPP_DEBUG_LEVEL == 2
     return iterator(__hold.release()->__as_link(), this);
-#else
-    return iterator(__hold.release()->__as_link());
-#endif
 }
 
 template <class _Tp, class _Alloc>
 typename list<_Tp, _Alloc>::iterator
 list<_Tp, _Alloc>::insert(const_iterator __p, size_type __n, const value_type& __x)
 {
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__p)) == this,
                          "list::insert(iterator, n, x) called with an iterator not referring to this list");
-#if _LIBCPP_DEBUG_LEVEL == 2
     iterator __r(__p.__ptr_, this);
-#else
-    iterator __r(__p.__ptr_);
-#endif
     if (__n > 0)
     {
         size_type __ds = 0;
         __node_allocator& __na = base::__node_alloc();
         __hold_pointer __hold = __allocate_node(__na);
         __node_alloc_traits::construct(__na, _VSTD::addressof(__hold->__value_), __x);
         ++__ds;
-#if _LIBCPP_DEBUG_LEVEL == 2
         __r = iterator(__hold->__as_link(), this);
-#else
-        __r = iterator(__hold->__as_link());
-#endif
         __hold.release();
         iterator __e = __r;
 #ifndef _LIBCPP_NO_EXCEPTIONS
         try
         {
 #endif // _LIBCPP_NO_EXCEPTIONS
             for (--__n; __n != 0; --__n, (void) ++__e, ++__ds)
             {
#ifndef _LIBCPP_NO_EXCEPTIONS
         {
             while (true)
             {
                 __node_alloc_traits::destroy(__na, _VSTD::addressof(*__e));
                 __link_pointer __prev = __e.__ptr_->__prev_;
                 __node_alloc_traits::deallocate(__na, __e.__ptr_->__as_node(), 1);
                 if (__prev == 0)
                     break;
-#if _LIBCPP_DEBUG_LEVEL == 2
                 __e = iterator(__prev, this);
-#else
-                __e = iterator(__prev);
-#endif
             }
             throw;
         }
 #endif // _LIBCPP_NO_EXCEPTIONS
         __link_nodes(__p.__ptr_, __r.__ptr_, __e.__ptr_);
         base::__sz() += __ds;
     }
     return __r;
 }
 
 template <class _Tp, class _Alloc>
 template <class _InpIter>
 typename list<_Tp, _Alloc>::iterator
 list<_Tp, _Alloc>::insert(const_iterator __p, _InpIter __f, _InpIter __l,
              typename enable_if<__is_cpp17_input_iterator<_InpIter>::value>::type*)
 {
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__p)) == this,
                          "list::insert(iterator, range) called with an iterator not referring to this list");
-#if _LIBCPP_DEBUG_LEVEL == 2
     iterator __r(__p.__ptr_, this);
-#else
-    iterator __r(__p.__ptr_);
-#endif
     if (__f != __l)
     {
         size_type __ds = 0;
         __node_allocator& __na = base::__node_alloc();
         __hold_pointer __hold = __allocate_node(__na);
         __node_alloc_traits::construct(__na, _VSTD::addressof(__hold->__value_), *__f);
         ++__ds;
-#if _LIBCPP_DEBUG_LEVEL == 2
         __r = iterator(__hold.get()->__as_link(), this);
-#else
-        __r = iterator(__hold.get()->__as_link());
-#endif
         __hold.release();
         iterator __e = __r;
 #ifndef _LIBCPP_NO_EXCEPTIONS
         try
         {
 #endif // _LIBCPP_NO_EXCEPTIONS
             for (++__f; __f != __l; ++__f, (void) ++__e, ++__ds)
             {
#ifndef _LIBCPP_NO_EXCEPTIONS
         {
             while (true)
             {
                 __node_alloc_traits::destroy(__na, _VSTD::addressof(*__e));
                 __link_pointer __prev = __e.__ptr_->__prev_;
                 __node_alloc_traits::deallocate(__na, __e.__ptr_->__as_node(), 1);
                 if (__prev == 0)
                     break;
-#if _LIBCPP_DEBUG_LEVEL == 2
                 __e = iterator(__prev, this);
-#else
-                __e = iterator(__prev);
-#endif
             }
             throw;
         }
 #endif // _LIBCPP_NO_EXCEPTIONS
         __link_nodes(__p.__ptr_, __r.__ptr_, __e.__ptr_);
         base::__sz() += __ds;
     }
     return __r;
_LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__p)) == this,
                          "list::emplace(iterator, args...) called with an iterator not referring to this list");
     __node_allocator& __na = base::__node_alloc();
     __hold_pointer __hold = __allocate_node(__na);
     __node_alloc_traits::construct(__na, _VSTD::addressof(__hold->__value_), _VSTD::forward<_Args>(__args)...);
     __link_pointer __nl = __hold.get()->__as_link();
     __link_nodes(__p.__ptr_, __nl, __nl);
     ++base::__sz();
     __hold.release();
-#if _LIBCPP_DEBUG_LEVEL == 2
     return iterator(__nl, this);
-#else
-    return iterator(__nl);
-#endif
 }
 
 template <class _Tp, class _Alloc>
 typename list<_Tp, _Alloc>::iterator
 list<_Tp, _Alloc>::insert(const_iterator __p, value_type&& __x)
 {
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__p)) == this,
                          "list::insert(iterator, x) called with an iterator not referring to this list");
     __node_allocator& __na = base::__node_alloc();
     __hold_pointer __hold = __allocate_node(__na);
     __node_alloc_traits::construct(__na, _VSTD::addressof(__hold->__value_), _VSTD::move(__x));
     __link_pointer __nl = __hold->__as_link();
     __link_nodes(__p.__ptr_, __nl, __nl);
     ++base::__sz();
     __hold.release();
-#if _LIBCPP_DEBUG_LEVEL == 2
     return iterator(__nl, this);
-#else
-    return iterator(__nl);
-#endif
 }
 
 #endif // _LIBCPP_CXX03_LANG
 
 template <class _Tp, class _Alloc>
 void
 list<_Tp, _Alloc>::pop_front()
 {
for (__i_node** __ip = __c->end_; __ip != __c->beg_; )
                 _VSTD::memmove(__ip, __ip+1, (__c->end_ - __ip)*sizeof(__i_node*));
         }
     }
     __get_db()->unlock();
 #endif
     __node_pointer __np = __n->__as_node();
     __node_alloc_traits::destroy(__na, _VSTD::addressof(__np->__value_));
     __node_alloc_traits::deallocate(__na, __np, 1);
-#if _LIBCPP_DEBUG_LEVEL == 2
     return iterator(__r, this);
-#else
-    return iterator(__r);
-#endif
 }
 
 template <class _Tp, class _Alloc>
 typename list<_Tp, _Alloc>::iterator
 list<_Tp, _Alloc>::erase(const_iterator __f, const_iterator __l)
 {
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__f)) == this,
                          "list::erase(iterator, iterator) called with an iterator not referring to this list");
#if _LIBCPP_DEBUG_LEVEL == 2
             }
             __get_db()->unlock();
 #endif
             __node_pointer __np = __n->__as_node();
             __node_alloc_traits::destroy(__na, _VSTD::addressof(__np->__value_));
             __node_alloc_traits::deallocate(__na, __np, 1);
         }
     }
-#if _LIBCPP_DEBUG_LEVEL == 2
     return iterator(__l.__ptr_, this);
-#else
-    return iterator(__l.__ptr_);
-#endif
 }
 
 template <class _Tp, class _Alloc>
 void
 list<_Tp, _Alloc>::resize(size_type __n)
 {
     if (__n < base::__sz())
         erase(__iterator(__n), end());
     else if (__n > base::__sz())
     {
         __n -= base::__sz();
         size_type __ds = 0;
         __node_allocator& __na = base::__node_alloc();
         __hold_pointer __hold = __allocate_node(__na);
         __node_alloc_traits::construct(__na, _VSTD::addressof(__hold->__value_));
         ++__ds;
-#if _LIBCPP_DEBUG_LEVEL == 2
         iterator __r = iterator(__hold.release()->__as_link(), this);
-#else
-        iterator __r = iterator(__hold.release()->__as_link());
-#endif
         iterator __e = __r;
 #ifndef _LIBCPP_NO_EXCEPTIONS
         try
         {
 #endif // _LIBCPP_NO_EXCEPTIONS
             for (--__n; __n != 0; --__n, (void) ++__e, ++__ds)
             {
                 __hold.reset(__node_alloc_traits::allocate(__na, 1));
                 __node_alloc_traits::construct(__na, _VSTD::addressof(__hold->__value_));
                 __e.__ptr_->__next_ = __hold.get()->__as_link();
                 __hold->__prev_ = __e.__ptr_;
                 __hold.release();
             }
 #ifndef _LIBCPP_NO_EXCEPTIONS
         }
         catch (...)
         {
             while (true)
             {
                 __node_alloc_traits::destroy(__na, _VSTD::addressof(*__e));
                 __link_pointer __prev = __e.__ptr_->__prev_;
                 __node_alloc_traits::deallocate(__na, __e.__ptr_->__as_node(), 1);
                 if (__prev == 0)
                     break;
-#if _LIBCPP_DEBUG_LEVEL == 2
                 __e = iterator(__prev, this);
-#else
-                __e = iterator(__prev);
-#endif
             }
             throw;
         }
 #endif // _LIBCPP_NO_EXCEPTIONS
         __link_nodes_at_back(__r.__ptr_, __e.__ptr_);
         base::__sz() += __ds;
     }
 }
 
 template <class _Tp, class _Alloc>
 void
 list<_Tp, _Alloc>::resize(size_type __n, const value_type& __x)
 {
     if (__n < base::__sz())
         erase(__iterator(__n), end());
     else if (__n > base::__sz())
     {
         __n -= base::__sz();
         size_type __ds = 0;
         __node_allocator& __na = base::__node_alloc();
         __hold_pointer __hold = __allocate_node(__na);
         __node_alloc_traits::construct(__na, _VSTD::addressof(__hold->__value_), __x);
         ++__ds;
         __link_pointer __nl = __hold.release()->__as_link();
-#if _LIBCPP_DEBUG_LEVEL == 2
         iterator __r = iterator(__nl, this);
-#else
-        iterator __r = iterator(__nl);
-#endif
         iterator __e = __r;
 #ifndef _LIBCPP_NO_EXCEPTIONS
         try
         {
 #endif // _LIBCPP_NO_EXCEPTIONS
             for (--__n; __n != 0; --__n, (void) ++__e, ++__ds)
             {
                 __hold.reset(__node_alloc_traits::allocate(__na, 1));
                 __node_alloc_traits::construct(__na, _VSTD::addressof(__hold->__value_), __x);
                 __e.__ptr_->__next_ = __hold.get()->__as_link();
                 __hold->__prev_ = __e.__ptr_;
                 __hold.release();
             }
 #ifndef _LIBCPP_NO_EXCEPTIONS
         }
         catch (...)
         {
             while (true)
             {
                 __node_alloc_traits::destroy(__na, _VSTD::addressof(*__e));
                 __link_pointer __prev = __e.__ptr_->__prev_;
                 __node_alloc_traits::deallocate(__na, __e.__ptr_->__as_node(), 1);
                 if (__prev == 0)
                     break;
-#if _LIBCPP_DEBUG_LEVEL == 2
                 __e = iterator(__prev, this);
-#else
-                __e = iterator(__prev);
-#endif
             }
             throw;
         }
 #endif // _LIBCPP_NO_EXCEPTIONS
         __link_nodes(base::__end_as_link(), __r.__ptr_, __e.__ptr_);
         base::__sz() += __ds;
     }
 }

libcxx/include/span

concept __span_compatible_range =
   ranges::sized_range<_Range> &&
   (ranges::borrowed_range<_Range> || is_const_v<_ElementType>) &&
   !__is_std_span<remove_cvref_t<_Range>>::value  &&
   !__is_std_array<remove_cvref_t<_Range>>::value &&
   !is_array_v<remove_cvref_t<_Range>> &&
   is_convertible_v<remove_reference_t<ranges::range_reference_t<_Range>>(*)[], _ElementType(*)[]>;
 #endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 
+#if (_LIBCPP_DEBUG_LEVEL == 2) || defined(_LIBCPP_ABI_SPAN_POINTER_ITERATORS)
+#   define _LIBCPP_SPAN_USE_POINTER_ITERATOR
+#endif
+
 template <typename _Tp, size_t _Extent>
 class _LIBCPP_TEMPLATE_VIS span {
 public:
 //  constants and types
     using element_type           = _Tp;
     using value_type             = remove_cv_t<_Tp>;
     using size_type              = size_t;
     using difference_type        = ptrdiff_t;
     using pointer                = _Tp *;
     using const_pointer          = const _Tp *;
     using reference              = _Tp &;
     using const_reference        = const _Tp &;
-#if (_LIBCPP_DEBUG_LEVEL == 2) || defined(_LIBCPP_ABI_SPAN_POINTER_ITERATORS)
+#ifdef _LIBCPP_SPAN_USE_POINTER_ITERATOR
     using iterator               = pointer;
 #else
     using iterator               = __wrap_iter<pointer>;
 #endif
     using reverse_iterator       = _VSTD::reverse_iterator<iterator>;
 
     static constexpr size_type extent = _Extent;
 
//  ~span() noexcept = default;
     {
         _LIBCPP_ASSERT(!empty(), "span<T, N>::back() on empty span");
         return __data[size()-1];
     }
 
     _LIBCPP_INLINE_VISIBILITY constexpr pointer data()                         const noexcept { return __data; }
 
 // [span.iter], span iterator support
-    _LIBCPP_INLINE_VISIBILITY constexpr iterator                 begin() const noexcept { return iterator(data()); }
-    _LIBCPP_INLINE_VISIBILITY constexpr iterator                   end() const noexcept { return iterator(data() + size()); }
+    _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept {
+#ifdef _LIBCPP_SPAN_USE_POINTER_ITERATOR
+        return iterator(data());
+#else
+        return iterator(this, data());
+#endif
+    }
+    _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept {
+#ifdef _LIBCPP_SPAN_USE_POINTER_ITERATOR
+        return iterator(data() + size());
+#else
+        return iterator(this, data() + size());
+#endif
+    }
     _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator        rbegin() const noexcept { return reverse_iterator(end()); }
     _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator          rend() const noexcept { return reverse_iterator(begin()); }
 
     _LIBCPP_INLINE_VISIBILITY span<const byte, _Extent * sizeof(element_type)> __as_bytes() const noexcept
     { return span<const byte, _Extent * sizeof(element_type)>{reinterpret_cast<const byte *>(data()), size_bytes()}; }
 
     _LIBCPP_INLINE_VISIBILITY span<byte, _Extent * sizeof(element_type)> __as_writable_bytes() const noexcept
     { return span<byte, _Extent * sizeof(element_type)>{reinterpret_cast<byte *>(data()), size_bytes()}; }
//  constants and types
     using element_type           = _Tp;
     using value_type             = remove_cv_t<_Tp>;
     using size_type              = size_t;
     using difference_type        = ptrdiff_t;
     using pointer                = _Tp *;
     using const_pointer          = const _Tp *;
     using reference              = _Tp &;
     using const_reference        = const _Tp &;
-#if (_LIBCPP_DEBUG_LEVEL == 2) || defined(_LIBCPP_ABI_SPAN_POINTER_ITERATORS)
+#ifdef _LIBCPP_SPAN_USE_POINTER_ITERATOR
     using iterator               = pointer;
 #else
     using iterator               = __wrap_iter<pointer>;
 #endif
     using reverse_iterator       = _VSTD::reverse_iterator<iterator>;
 
     static constexpr size_type extent = dynamic_extent;
 
_LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept
         _LIBCPP_ASSERT(!empty(), "span<T>[].back() on empty span");
         return __data[size()-1];
     }
 
 
     _LIBCPP_INLINE_VISIBILITY constexpr pointer data()                         const noexcept { return __data; }
 
 // [span.iter], span iterator support
-    _LIBCPP_INLINE_VISIBILITY constexpr iterator                 begin() const noexcept { return iterator(data()); }
-    _LIBCPP_INLINE_VISIBILITY constexpr iterator                   end() const noexcept { return iterator(data() + size()); }
+    _LIBCPP_INLINE_VISIBILITY constexpr iterator begin() const noexcept {
+#ifdef _LIBCPP_SPAN_USE_POINTER_ITERATOR
+        return iterator(data());
+#else
+        return iterator(this, data());
+#endif
+    }
+    _LIBCPP_INLINE_VISIBILITY constexpr iterator end() const noexcept {
+#ifdef _LIBCPP_SPAN_USE_POINTER_ITERATOR
+        return iterator(data() + size());
+#else
+        return iterator(this, data() + size());
+#endif
+    }
     _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator        rbegin() const noexcept { return reverse_iterator(end()); }
     _LIBCPP_INLINE_VISIBILITY constexpr reverse_iterator          rend() const noexcept { return reverse_iterator(begin()); }
 
     _LIBCPP_INLINE_VISIBILITY span<const byte, dynamic_extent> __as_bytes() const noexcept
     { return {reinterpret_cast<const byte *>(data()), size_bytes()}; }
 
     _LIBCPP_INLINE_VISIBILITY span<byte, dynamic_extent> __as_writable_bytes() const noexcept
     { return {reinterpret_cast<byte *>(data()), size_bytes()}; }

libcxx/include/string

 #endif
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
     basic_string& operator=(const value_type* __s) {return assign(__s);}
 #if _LIBCPP_STD_VER > 20
     basic_string& operator=(nullptr_t) = delete;
 #endif
     _LIBCPP_CONSTEXPR_AFTER_CXX17 basic_string& operator=(value_type __c);
 
-#if _LIBCPP_DEBUG_LEVEL == 2
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
     iterator begin() _NOEXCEPT
         {return iterator(this, __get_pointer());}
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
     const_iterator begin() const _NOEXCEPT
         {return const_iterator(this, __get_pointer());}
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
     iterator end() _NOEXCEPT
         {return iterator(this, __get_pointer() + size());}
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
     const_iterator end() const _NOEXCEPT
         {return const_iterator(this, __get_pointer() + size());}
-#else
-    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
-    iterator begin() _NOEXCEPT
-        {return iterator(__get_pointer());}
-    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
-    const_iterator begin() const _NOEXCEPT
-        {return const_iterator(__get_pointer());}
-    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
-    iterator end() _NOEXCEPT
-        {return iterator(__get_pointer() + size());}
-    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
-    const_iterator end() const _NOEXCEPT
-        {return const_iterator(__get_pointer() + size());}
-#endif // _LIBCPP_DEBUG_LEVEL == 2
+
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
     reverse_iterator rbegin() _NOEXCEPT
         {return reverse_iterator(end());}
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
     const_reverse_iterator rbegin() const _NOEXCEPT
         {return const_reverse_iterator(end());}
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
     reverse_iterator rend() _NOEXCEPT

libcxx/include/vector

else
         __construct_at_end(__n, __u);
     }
     std::__debug_db_invalidate_all(this);
 }
 
 template <class _Tp, class _Allocator>
 inline _LIBCPP_INLINE_VISIBILITY
 typename vector<_Tp, _Allocator>::iterator
-vector<_Tp, _Allocator>::__make_iter(pointer __p) _NOEXCEPT
-{
-#if _LIBCPP_DEBUG_LEVEL == 2
-    return iterator(this, __p);
-#else
-    return iterator(__p);
-#endif
-}
-
-template <class _Tp, class _Allocator>
-inline _LIBCPP_INLINE_VISIBILITY
-typename vector<_Tp, _Allocator>::const_iterator
-vector<_Tp, _Allocator>::__make_iter(const_pointer __p) const _NOEXCEPT
-{
-#if _LIBCPP_DEBUG_LEVEL == 2
-    return const_iterator(this, __p);
-#else
-    return const_iterator(__p);
-#endif
-}
-
-template <class _Tp, class _Allocator>
-inline _LIBCPP_INLINE_VISIBILITY
-typename vector<_Tp, _Allocator>::iterator
 vector<_Tp, _Allocator>::begin() _NOEXCEPT
 {
-    return __make_iter(this->__begin_);
+    return iterator(this, this->__begin_);
 }
 
 template <class _Tp, class _Allocator>
 inline _LIBCPP_INLINE_VISIBILITY
 typename vector<_Tp, _Allocator>::const_iterator
 vector<_Tp, _Allocator>::begin() const _NOEXCEPT
 {
-    return __make_iter(this->__begin_);
+    return const_iterator(this, this->__begin_);
 }
 
 template <class _Tp, class _Allocator>
 inline _LIBCPP_INLINE_VISIBILITY
 typename vector<_Tp, _Allocator>::iterator
 vector<_Tp, _Allocator>::end() _NOEXCEPT
 {
-    return __make_iter(this->__end_);
+    return iterator(this, this->__end_);
 }
 
 template <class _Tp, class _Allocator>
 inline _LIBCPP_INLINE_VISIBILITY
 typename vector<_Tp, _Allocator>::const_iterator
 vector<_Tp, _Allocator>::end() const _NOEXCEPT
 {
-    return __make_iter(this->__end_);
+    return const_iterator(this, this->__end_);
 }
 
 template <class _Tp, class _Allocator>
 inline _LIBCPP_INLINE_VISIBILITY
 typename vector<_Tp, _Allocator>::reference
 vector<_Tp, _Allocator>::operator[](size_type __n) _NOEXCEPT
 {
     _LIBCPP_ASSERT(__n < size(), "vector[] index out of bounds");
vector<_Tp, _Allocator>::erase(const_iterator __position)
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__position)) == this,
                          "vector::erase(iterator) called with an iterator not referring to this vector");
     _LIBCPP_ASSERT(__position != end(),
         "vector::erase(iterator) called with a non-dereferenceable iterator");
     difference_type __ps = __position - cbegin();
     pointer __p = this->__begin_ + __ps;
     this->__destruct_at_end(_VSTD::move(__p + 1, this->__end_, __p));
     this->__invalidate_iterators_past(__p-1);
-    iterator __r = __make_iter(__p);
+    iterator __r = iterator(this, __p);
     return __r;
 }
 
 template <class _Tp, class _Allocator>
 typename vector<_Tp, _Allocator>::iterator
 vector<_Tp, _Allocator>::erase(const_iterator __first, const_iterator __last)
 {
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__first)) == this,
                          "vector::erase(iterator, iterator) called with an iterator not referring to this vector");
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__last)) == this,
                          "vector::erase(iterator, iterator) called with an iterator not referring to this vector");
 
     _LIBCPP_ASSERT(__first <= __last, "vector::erase(first, last) called with invalid range");
     pointer __p = this->__begin_ + (__first - begin());
     if (__first != __last) {
         this->__destruct_at_end(_VSTD::move(__p + (__last - __first), this->__end_, __p));
         this->__invalidate_iterators_past(__p - 1);
     }
-    iterator __r = __make_iter(__p);
+    iterator __r = iterator(this, __p);
     return __r;
 }
 
 template <class _Tp, class _Allocator>
 void
 vector<_Tp, _Allocator>::__move_range(pointer __from_s, pointer __from_e, pointer __to)
 {
     pointer __old_last = this->__end_;
vector<_Tp, _Allocator>::insert(const_iterator __position, const_reference __x)
     }
     else
     {
         allocator_type& __a = this->__alloc();
         __split_buffer<value_type, allocator_type&> __v(__recommend(size() + 1), __p - this->__begin_, __a);
         __v.push_back(__x);
         __p = __swap_out_circular_buffer(__v, __p);
     }
-    return __make_iter(__p);
+    return iterator(this, __p);
 }
 
 template <class _Tp, class _Allocator>
 typename vector<_Tp, _Allocator>::iterator
 vector<_Tp, _Allocator>::insert(const_iterator __position, value_type&& __x)
 {
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__position)) == this,
                          "vector::insert(iterator, x) called with an iterator not referring to this vector");
vector<_Tp, _Allocator>::insert(const_iterator __position, value_type&& __x)
     }
     else
     {
         allocator_type& __a = this->__alloc();
         __split_buffer<value_type, allocator_type&> __v(__recommend(size() + 1), __p - this->__begin_, __a);
         __v.push_back(_VSTD::move(__x));
         __p = __swap_out_circular_buffer(__v, __p);
     }
-    return __make_iter(__p);
+    return iterator(this, __p);
 }
 
 template <class _Tp, class _Allocator>
 template <class... _Args>
 typename vector<_Tp, _Allocator>::iterator
 vector<_Tp, _Allocator>::emplace(const_iterator __position, _Args&&... __args)
 {
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__position)) == this,
vector<_Tp, _Allocator>::emplace(const_iterator __position, _Args&&... __args)
     }
     else
     {
         allocator_type& __a = this->__alloc();
         __split_buffer<value_type, allocator_type&> __v(__recommend(size() + 1), __p - this->__begin_, __a);
         __v.emplace_back(_VSTD::forward<_Args>(__args)...);
         __p = __swap_out_circular_buffer(__v, __p);
     }
-    return __make_iter(__p);
+    return iterator(this, __p);
 }
 
 template <class _Tp, class _Allocator>
 typename vector<_Tp, _Allocator>::iterator
 vector<_Tp, _Allocator>::insert(const_iterator __position, size_type __n, const_reference __x)
 {
     _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__position)) == this,
                          "vector::insert(iterator, n, x) called with an iterator not referring to this vector");
if (__n > 0)
         else
         {
             allocator_type& __a = this->__alloc();
             __split_buffer<value_type, allocator_type&> __v(__recommend(size() + __n), __p - this->__begin_, __a);
             __v.__construct_at_end(__n, __x);
             __p = __swap_out_circular_buffer(__v, __p);
         }
     }
-    return __make_iter(__p);
+    return iterator(this, __p);
 }
 
 template <class _Tp, class _Allocator>
 template <class _InputIterator>
 typename enable_if
 <
      __is_cpp17_input_iterator  <_InputIterator>::value &&
     !__is_cpp17_forward_iterator<_InputIterator>::value &&
#endif // _LIBCPP_NO_EXCEPTIONS
             difference_type __old_p = __p - this->__begin_;
             reserve(__recommend(size() + __v.size()));
             __p = this->__begin_ + __old_p;
             __old_last = this->__begin_ + __old_size;
 #ifndef _LIBCPP_NO_EXCEPTIONS
         }
         catch (...)
         {
-            erase(__make_iter(__old_last), end());
+            erase(iterator(this, __old_last), end());
             throw;
         }
 #endif // _LIBCPP_NO_EXCEPTIONS
     }
     __p = _VSTD::rotate(__p, __old_last, this->__end_);
-    insert(__make_iter(__p), _VSTD::make_move_iterator(__v.begin()),
+    insert(iterator(this, __p), _VSTD::make_move_iterator(__v.begin()),
                                 _VSTD::make_move_iterator(__v.end()));
     return begin() + __off;
 }
 
 template <class _Tp, class _Allocator>
 template <class _ForwardIterator>
 typename enable_if
 <
     __is_cpp17_forward_iterator<_ForwardIterator>::value &&
if (__n > 0)
         else
         {
             allocator_type& __a = this->__alloc();
             __split_buffer<value_type, allocator_type&> __v(__recommend(size() + __n), __p - this->__begin_, __a);
             __v.__construct_at_end(__first, __last);
             __p = __swap_out_circular_buffer(__v, __p);
         }
     }
-    return __make_iter(__p);
+    return iterator(this, __p);
 }
 
 template <class _Tp, class _Allocator>
 void
 vector<_Tp, _Allocator>::resize(size_type __sz)
 {
     size_type __cs = size();
     if (__cs < __sz)