[libc++] Introduce helper functions __make_iter in vector and string

[ldionne]

Summary

This prepares the terrain for introducing a new type of bounded iterator
that can't be constructed like __wrap_iter. This reverts part of the
changes made to std::vector in 4eab04f84.

[ldionne]

Fix CI

libcxx/include/string

explicit basic_string(__uninitialized_size_tag, size_type __size, const allocator_type& __a)
             __begin_lifetime(__allocation, __capacity);
             __set_long_cap(__capacity);
             __set_long_pointer(__allocation);
             __set_long_size(__size);
         }
         std::__debug_db_insert_c(this);
     }
 
+    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator __make_iterator(pointer __p) {
+        return iterator(this, __p);
+    }
+
+    _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_iterator __make_const_iterator(const_pointer __p) const {
+        return const_iterator(this, __p);
+    }
+
 public:
   _LIBCPP_TEMPLATE_DATA_VIS static const size_type npos = -1;
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string()
       _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
       : __r_(__default_init_tag(), __default_init_tag()) {
     std::__debug_db_insert_c(this);
     __default_init();
#endif
     basic_string& operator=(const value_type* __s) {return assign(__s);}
 #if _LIBCPP_STD_VER > 20
     basic_string& operator=(nullptr_t) = delete;
 #endif
     _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& operator=(value_type __c);
 
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
     iterator begin() _NOEXCEPT
-        {return iterator(this, __get_pointer());}
+        {return __make_iterator(__get_pointer());}
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
     const_iterator begin() const _NOEXCEPT
-        {return const_iterator(this, __get_pointer());}
+        {return __make_const_iterator(__get_pointer());}
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
     iterator end() _NOEXCEPT
-        {return iterator(this, __get_pointer() + size());}
+        {return __make_iterator(__get_pointer() + size());}
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
     const_iterator end() const _NOEXCEPT
-        {return const_iterator(this, __get_pointer() + size());}
+        {return __make_const_iterator(__get_pointer() + size());}
 
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
     reverse_iterator rbegin() _NOEXCEPT
         {return reverse_iterator(end());}
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
     const_reverse_iterator rbegin() const _NOEXCEPT
         {return const_reverse_iterator(end());}
     _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20

libcxx/include/vector

private:
 
   template <class _ForwardIterator, __enable_if_t<__is_cpp17_forward_iterator<_ForwardIterator>::value, int> = 0>
   _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
   __construct_at_end(_ForwardIterator __first, _ForwardIterator __last, size_type __n);
 
     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __append(size_type __n);
     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __append(size_type __n, const_reference __x);
     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI
-    iterator       __make_iter(pointer __p) _NOEXCEPT;
+    iterator       __make_iter(pointer __p) _NOEXCEPT { return iterator(this, __p); }
     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI
-    const_iterator __make_iter(const_pointer __p) const _NOEXCEPT;
+    const_iterator __make_iter(const_pointer __p) const _NOEXCEPT { return const_iterator(this, __p); }
     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __swap_out_circular_buffer(__split_buffer<value_type, allocator_type&>& __v);
     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI pointer __swap_out_circular_buffer(__split_buffer<value_type, allocator_type&>& __v, pointer __p);
     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __move_range(pointer __from_s, pointer __from_e, pointer __to);
     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __move_assign(vector& __c, true_type)
         _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __move_assign(vector& __c, false_type)
         _NOEXCEPT_(__alloc_traits::is_always_equal::value);
     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI

 }
 
 template <class _Tp, class _Allocator>
 _LIBCPP_CONSTEXPR_SINCE_CXX20
 inline _LIBCPP_HIDE_FROM_ABI
 typename vector<_Tp, _Allocator>::iterator
 vector<_Tp, _Allocator>::begin() _NOEXCEPT
 {
-    return iterator(this, this->__begin_);
+    return __make_iter(this->__begin_);
 }
 
 template <class _Tp, class _Allocator>
 _LIBCPP_CONSTEXPR_SINCE_CXX20
 inline _LIBCPP_HIDE_FROM_ABI
 typename vector<_Tp, _Allocator>::const_iterator
 vector<_Tp, _Allocator>::begin() const _NOEXCEPT
 {
-    return const_iterator(this, this->__begin_);
+    return __make_iter(this->__begin_);
 }
 
 template <class _Tp, class _Allocator>
 _LIBCPP_CONSTEXPR_SINCE_CXX20
 inline _LIBCPP_HIDE_FROM_ABI
 typename vector<_Tp, _Allocator>::iterator
 vector<_Tp, _Allocator>::end() _NOEXCEPT
 {
-    return iterator(this, this->__end_);
+    return __make_iter(this->__end_);
 }
 
 template <class _Tp, class _Allocator>
 _LIBCPP_CONSTEXPR_SINCE_CXX20
 inline _LIBCPP_HIDE_FROM_ABI
 typename vector<_Tp, _Allocator>::const_iterator
 vector<_Tp, _Allocator>::end() const _NOEXCEPT
 {
-    return const_iterator(this, this->__end_);
+    return __make_iter(this->__end_);
 }
 
 template <class _Tp, class _Allocator>
 _LIBCPP_CONSTEXPR_SINCE_CXX20
 inline _LIBCPP_HIDE_FROM_ABI
 typename vector<_Tp, _Allocator>::reference
 vector<_Tp, _Allocator>::operator[](size_type __n) _NOEXCEPT
 {
_LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(std::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(std::move(__p + 1, this->__end_, __p));
     if (!__libcpp_is_constant_evaluated())
         this->__invalidate_iterators_past(__p - 1);
-    iterator __r = iterator(this, __p);
-    return __r;
+    return __make_iter(__p);
 }
 
 template <class _Tp, class _Allocator>
 _LIBCPP_CONSTEXPR_SINCE_CXX20
 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(std::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(std::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(std::move(__p + (__last - __first), this->__end_, __p));
         if (!__libcpp_is_constant_evaluated())
             this->__invalidate_iterators_past(__p - 1);
     }
-    iterator __r = iterator(this, __p);
-    return __r;
+    return __make_iter(__p);
 }
 
 template <class _Tp, class _Allocator>
 _LIBCPP_CONSTEXPR_SINCE_CXX20
 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 iterator(this, __p);
+    return __make_iter(__p);
 }
 
 template <class _Tp, class _Allocator>
 _LIBCPP_CONSTEXPR_SINCE_CXX20
 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(std::addressof(__position)) == this,
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(std::move(__x));
         __p = __swap_out_circular_buffer(__v, __p);
     }
-    return iterator(this, __p);
+    return __make_iter(__p);
 }
 
 template <class _Tp, class _Allocator>
 template <class... _Args>
 _LIBCPP_CONSTEXPR_SINCE_CXX20
 typename vector<_Tp, _Allocator>::iterator
 vector<_Tp, _Allocator>::emplace(const_iterator __position, _Args&&... __args)
 {
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(std::forward<_Args>(__args)...);
         __p = __swap_out_circular_buffer(__v, __p);
     }
-    return iterator(this, __p);
+    return __make_iter(__p);
 }
 
 template <class _Tp, class _Allocator>
 _LIBCPP_CONSTEXPR_SINCE_CXX20
 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(std::addressof(__position)) == this,
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 iterator(this, __p);
+    return __make_iter(__p);
 }
 
 template <class _Tp, class _Allocator>
 template <class _InputIterator, __enable_if_t<__is_exactly_cpp17_input_iterator<_InputIterator>::value &&
                               is_constructible<_Tp, typename iterator_traits<_InputIterator>::reference>::value,
                           int> >
 _LIBCPP_CONSTEXPR_SINCE_CXX20 typename vector<_Tp, _Allocator>::iterator
 vector<_Tp, _Allocator>::insert(const_iterator __position, _InputIterator __first, _InputIterator __last)
#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(iterator(this, __old_last), end());
+            erase(__make_iter(__old_last), end());
             throw;
         }
 #endif // _LIBCPP_NO_EXCEPTIONS
     }
     __p = std::rotate(__p, __old_last, this->__end_);
-    insert(iterator(this, __p), std::make_move_iterator(__v.begin()),
-                                std::make_move_iterator(__v.end()));
+    insert(__make_iter(__p), std::make_move_iterator(__v.begin()),
     return begin() + __off;
 }
 
 template <class _Tp, class _Allocator>
 template <class _ForwardIterator, __enable_if_t<__is_cpp17_forward_iterator<_ForwardIterator>::value &&
                         is_constructible<_Tp, typename iterator_traits<_ForwardIterator>::reference>::value,
                     int> >
 _LIBCPP_CONSTEXPR_SINCE_CXX20 typename vector<_Tp, _Allocator>::iterator
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 iterator(this, __p);
+    return __make_iter(__p);
 }
 
 template <class _Tp, class _Allocator>
 _LIBCPP_CONSTEXPR_SINCE_CXX20
 void
 vector<_Tp, _Allocator>::resize(size_type __sz)
 {
     size_type __cs = size();