Define std::__to_address helper

diff --git a/libstdc++-v3/include/bits/allocated_ptr.h b/libstdc++-v3/include/bits/allocated_ptr.h
index 773b3f500f0..96d7841b65b 100644
--- a/libstdc++-v3/include/bits/allocated_ptr.h
+++ b/libstdc++-v3/include/bits/allocated_ptr.h
@@ -82,16 +82,9 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
 
       /// Get the address that the owned pointer refers to.
-      value_type* get() { return _S_raw_ptr(_M_ptr); }
+      value_type* get() { return std::__to_address(_M_ptr); }
 
     private:
-      static value_type* _S_raw_ptr(value_type* __ptr) { return __ptr; }
-
-      template<typename _Ptr>
-	static auto
-	_S_raw_ptr(_Ptr __ptr) -> decltype(_S_raw_ptr(__ptr.operator->()))
-	{ return _S_raw_ptr(__ptr.operator->()); }
-
       _Alloc* _M_alloc;
       pointer _M_ptr;
     };
diff --git a/libstdc++-v3/include/bits/forward_list.h b/libstdc++-v3/include/bits/forward_list.h
index 9d86fcc1568..855a72815ae 100644
--- a/libstdc++-v3/include/bits/forward_list.h
+++ b/libstdc++-v3/include/bits/forward_list.h
@@ -336,7 +336,7 @@  _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
       _M_get_node()
       {
 	auto __ptr = _Node_alloc_traits::allocate(_M_get_Node_allocator(), 1);
-	return std::__addressof(*__ptr);
+	return std::__to_address(__ptr);
       }
 
       template<typename... _Args>
diff --git a/libstdc++-v3/include/bits/hashtable_policy.h b/libstdc++-v3/include/bits/hashtable_policy.h
index 5f2d8776aaa..da6d49c96c4 100644
--- a/libstdc++-v3/include/bits/hashtable_policy.h
+++ b/libstdc++-v3/include/bits/hashtable_policy.h
@@ -2048,7 +2048,7 @@  namespace __detail
       _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
       {
 	auto __nptr = __node_alloc_traits::allocate(_M_node_allocator(), 1);
-	__node_type* __n = std::__addressof(*__nptr);
+	__node_type* __n = std::__to_address(__nptr);
 	__try
 	  {
 	    ::new ((void*)__n) __node_type;
@@ -2094,7 +2094,7 @@  namespace __detail
       __bucket_alloc_type __alloc(_M_node_allocator());
 
       auto __ptr = __bucket_alloc_traits::allocate(__alloc, __n);
-      __bucket_type* __p = std::__addressof(*__ptr);
+      __bucket_type* __p = std::__to_address(__ptr);
       __builtin_memset(__p, 0, __n * sizeof(__bucket_type));
       return __p;
     }
diff --git a/libstdc++-v3/include/bits/ptr_traits.h b/libstdc++-v3/include/bits/ptr_traits.h
index 797e7fcec39..74d4c18126c 100644
--- a/libstdc++-v3/include/bits/ptr_traits.h
+++ b/libstdc++-v3/include/bits/ptr_traits.h
@@ -146,6 +146,16 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<typename _Ptr, typename _Tp>
     using __ptr_rebind = typename pointer_traits<_Ptr>::template rebind<_Tp>;
 
+  template<typename _Tp>
+    constexpr _Tp*
+    __to_address(_Tp* __ptr) noexcept
+    { return __ptr; }
+
+  template<typename _Ptr>
+    constexpr typename std::pointer_traits<_Ptr>::element_type*
+    __to_address(const _Ptr& __ptr)
+    { return std::__to_address(__ptr.operator->()); }
+
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std
 
diff --git a/libstdc++-v3/include/bits/shared_ptr_base.h b/libstdc++-v3/include/bits/shared_ptr_base.h
index 7e6766ba7d5..20504f326e8 100644
--- a/libstdc++-v3/include/bits/shared_ptr_base.h
+++ b/libstdc++-v3/include/bits/shared_ptr_base.h
@@ -1185,7 +1185,7 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	__shared_ptr(unique_ptr<_Yp, _Del>&& __r)
 	: _M_ptr(__r.get()), _M_refcount()
 	{
-	  auto __raw = _S_raw_ptr(__r.get());
+	  auto __raw = __to_address(__r.get());
 	  _M_refcount = __shared_count<_Lp>(std::move(__r));
 	  _M_enable_shared_from_this_with(__raw);
 	}
@@ -1201,7 +1201,7 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	__shared_ptr(unique_ptr<_Tp1, _Del>&& __r, __sp_array_delete)
 	: _M_ptr(__r.get()), _M_refcount()
 	{
-	  auto __raw = _S_raw_ptr(__r.get());
+	  auto __raw = __to_address(__r.get());
 	  _M_refcount = __shared_count<_Lp>(std::move(__r));
 	  _M_enable_shared_from_this_with(__raw);
 	}
@@ -1386,16 +1386,6 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
       _M_get_deleter(const std::type_info& __ti) const noexcept
       { return _M_refcount._M_get_deleter(__ti); }
 
-      template<typename _Tp1>
-	static _Tp1*
-	_S_raw_ptr(_Tp1* __ptr)
-	{ return __ptr; }
-
-      template<typename _Tp1>
-	static auto
-	_S_raw_ptr(_Tp1 __ptr) -> decltype(std::__addressof(*__ptr))
-	{ return std::__addressof(*__ptr); }
-
       template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
       template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
 
diff --git a/libstdc++-v3/include/bits/stl_vector.h b/libstdc++-v3/include/bits/stl_vector.h
index 69cb8030208..c7634216c01 100644
--- a/libstdc++-v3/include/bits/stl_vector.h
+++ b/libstdc++-v3/include/bits/stl_vector.h
@@ -1695,7 +1695,7 @@  _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
       template<typename _Ptr>
 	typename std::pointer_traits<_Ptr>::element_type*
 	_M_data_ptr(_Ptr __ptr) const
-	{ return empty() ? nullptr : std::__addressof(*__ptr); }
+	{ return empty() ? nullptr : std::__to_address(__ptr); }
 #else
       template<typename _Up>
 	_Up*
@@ -1705,12 +1705,12 @@  _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
       template<typename _Ptr>
 	value_type*
 	_M_data_ptr(_Ptr __ptr)
-	{ return __ptr.operator->(); }
+	{ return empty() ? (value_type*)0 : __ptr.operator->(); }
 
       template<typename _Ptr>
 	const value_type*
 	_M_data_ptr(_Ptr __ptr) const
-	{ return __ptr.operator->(); }
+	{ return empty() ? (const value_type*)0 : __ptr.operator->(); }
 #endif
     };
 
diff --git a/libstdc++-v3/include/ext/alloc_traits.h b/libstdc++-v3/include/ext/alloc_traits.h
index fe5655100a4..c6f44950007 100644
--- a/libstdc++-v3/include/ext/alloc_traits.h
+++ b/libstdc++-v3/include/ext/alloc_traits.h
@@ -81,7 +81,7 @@  template<typename _Alloc, typename = typename _Alloc::value_type>
       static typename std::enable_if<__is_custom_pointer<_Ptr>::value>::type
       construct(_Alloc& __a, _Ptr __p, _Args&&... __args)
       {
-	_Base_type::construct(__a, std::addressof(*__p),
+	_Base_type::construct(__a, std::__to_address(__p),
 			      std::forward<_Args>(__args)...);
       }
 
@@ -89,7 +89,7 @@  template<typename _Alloc, typename = typename _Alloc::value_type>
     template<typename _Ptr>
       static typename std::enable_if<__is_custom_pointer<_Ptr>::value>::type
       destroy(_Alloc& __a, _Ptr __p)
-      { _Base_type::destroy(__a, std::addressof(*__p)); }
+      { _Base_type::destroy(__a, std::__to_address(__p)); }
 
     static _Alloc _S_select_on_copy(const _Alloc& __a)
     { return _Base_type::select_on_container_copy_construction(__a); }