[libc++] Remove obsolete accessors in std::list and std::forward_list (#115748)

We don't need these accessors anymore now that we stopped using
compressed-pair.

Author: ldionne

libcxx/include/forward_list

@@ -503,9 +503,6 @@ protected:
     return pointer_traits<__begin_node_pointer>::pointer_to(const_cast<__begin_node&>(__before_begin_));
   }
 
-  _LIBCPP_HIDE_FROM_ABI __node_allocator& __alloc() _NOEXCEPT { return __alloc_; }
-  _LIBCPP_HIDE_FROM_ABI const __node_allocator& __alloc() const _NOEXCEPT { return __alloc_; }
-
   typedef __forward_list_iterator<__node_pointer> iterator;
   typedef __forward_list_const_iterator<__node_pointer> const_iterator;
 
@@ -541,8 +538,7 @@ protected:
 
   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI __node_pointer __create_node(__node_pointer __next, _Args&&... __args) {
-    __node_allocator& __a = __alloc();
-    __allocation_guard<__node_allocator> __guard(__a, 1);
+    __allocation_guard<__node_allocator> __guard(__alloc_, 1);
     // Begin the lifetime of the node itself. Note that this doesn't begin the lifetime of the value
     // held inside the node, since we need to use the allocator's construct() method for that.
     //
@@ -552,17 +548,16 @@ protected:
     std::__construct_at(std::addressof(*__guard.__get()), __next);
 
     // Now construct the value_type using the allocator's construct() method.
-    __node_traits::construct(__a, std::addressof(__guard.__get()->__get_value()), std::forward<_Args>(__args)...);
+    __node_traits::construct(__alloc_, std::addressof(__guard.__get()->__get_value()), std::forward<_Args>(__args)...);
     return __guard.__release_ptr();
   }
 
   _LIBCPP_HIDE_FROM_ABI void __delete_node(__node_pointer __node) {
     // For the same reason as above, we use the allocator's destroy() method for the value_type,
     // but not for the node itself.
-    __node_allocator& __a = __alloc();
-    __node_traits::destroy(__a, std::addressof(__node->__get_value()));
+    __node_traits::destroy(__alloc_, std::addressof(__node->__get_value()));
     std::__destroy_at(std::addressof(*__node));
-    __node_traits::deallocate(__a, __node, 1);
+    __node_traits::deallocate(__alloc_, __node, 1);
   }
 
 public:
@@ -579,15 +574,15 @@ protected:
 private:
   _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const __forward_list_base&, false_type) {}
   _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const __forward_list_base& __x, true_type) {
-    if (__alloc() != __x.__alloc())
+    if (__alloc_ != __x.__alloc_)
       clear();
-    __alloc() = __x.__alloc();
+    __alloc_ = __x.__alloc_;
   }
 
   _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(__forward_list_base&, false_type) _NOEXCEPT {}
   _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(__forward_list_base& __x, true_type)
       _NOEXCEPT_(is_nothrow_move_assignable<__node_allocator>::value) {
-    __alloc() = std::move(__x.__alloc());
+    __alloc_ = std::move(__x.__alloc_);
   }
 };
 
@@ -603,7 +598,7 @@ inline __forward_list_base<_Tp, _Alloc>::__forward_list_base(__forward_list_base
 template <class _Tp, class _Alloc>
 inline __forward_list_base<_Tp, _Alloc>::__forward_list_base(__forward_list_base&& __x, const allocator_type& __a)
     : __before_begin_(__begin_node()), __alloc_(__node_allocator(__a)) {
-  if (__alloc() == __x.__alloc()) {
+  if (__alloc_ == __x.__alloc_) {
     __before_begin()->__next_     = __x.__before_begin()->__next_;
     __x.__before_begin()->__next_ = nullptr;
   }
@@ -624,7 +619,7 @@ inline void __forward_list_base<_Tp, _Alloc>::swap(__forward_list_base& __x)
     _NOEXCEPT_(!__node_traits::propagate_on_container_swap::value || __is_nothrow_swappable_v<__node_allocator>)
 #endif
 {
-  std::__swap_allocator(__alloc(), __x.__alloc());
+  std::__swap_allocator(__alloc_, __x.__alloc_);
   using std::swap;
   swap(__before_begin()->__next_, __x.__before_begin()->__next_);
 }
@@ -739,7 +734,7 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI void assign(size_type __n, const value_type& __v);
 
-  _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT { return allocator_type(__base::__alloc()); }
+  _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT { return allocator_type(this->__alloc_); }
 
   _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return iterator(__base::__before_begin()->__next_); }
   _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT {
@@ -765,7 +760,7 @@ public:
     return __base::__before_begin()->__next_ == nullptr;
   }
   _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
-    return std::min<size_type>(__node_traits::max_size(__base::__alloc()), numeric_limits<difference_type>::max());
+    return std::min<size_type>(__node_traits::max_size(this->__alloc_), numeric_limits<difference_type>::max());
   }
 
   _LIBCPP_HIDE_FROM_ABI reference front() { return __base::__before_begin()->__next_->__get_value(); }
@@ -944,7 +939,7 @@ forward_list<_Tp, _Alloc>::forward_list(_InputIterator __f, _InputIterator __l,
 
 template <class _Tp, class _Alloc>
 forward_list<_Tp, _Alloc>::forward_list(const forward_list& __x)
-    : __base(__node_traits::select_on_container_copy_construction(__x.__alloc())) {
+    : __base(__node_traits::select_on_container_copy_construction(__x.__alloc_)) {
   insert_after(cbefore_begin(), __x.begin(), __x.end());
 }
 
@@ -967,7 +962,7 @@ forward_list<_Tp, _Alloc>& forward_list<_Tp, _Alloc>::operator=(const forward_li
 template <class _Tp, class _Alloc>
 forward_list<_Tp, _Alloc>::forward_list(forward_list&& __x, const __type_identity_t<allocator_type>& __a)
     : __base(std::move(__x), __a) {
-  if (__base::__alloc() != __x.__alloc()) {
+  if (this->__alloc_ != __x.__alloc_) {
     typedef move_iterator<iterator> _Ip;
     insert_after(cbefore_begin(), _Ip(__x.begin()), _Ip(__x.end()));
   }
@@ -994,7 +989,7 @@ void forward_list<_Tp, _Alloc>::__move_assign(forward_list& __x, true_type)
 
 template <class _Tp, class _Alloc>
 void forward_list<_Tp, _Alloc>::__move_assign(forward_list& __x, false_type) {
-  if (__base::__alloc() == __x.__alloc())
+  if (this->__alloc_ == __x.__alloc_)
     __move_assign(__x, true_type());
   else {
     typedef move_iterator<iterator> _Ip;