Fix for LWG2454: Add raw_storage_iterator::base() member

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@236948 91177308-0d34-0410-b5e6-96231b3b80d8

include/memory

@@ -1855,6 +1855,9 @@ public:
     _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator++() {++__x_; return *this;}
     _LIBCPP_INLINE_VISIBILITY raw_storage_iterator  operator++(int)
         {raw_storage_iterator __t(*this); ++__x_; return __t;}
+#if _LIBCPP_STD_VER >= 14
+    _LIBCPP_INLINE_VISIBILITY _OutputIterator base() const { return __x_; } 
+#endif
 };
 
 template <class _Tp>

test/std/utilities/memory/storage.iterator/raw_storag_iterator.base.pass.cpp

@@ -0,0 +1,48 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// raw_storage_iterator
+
+#include <memory>
+#include <type_traits>
+#include <cassert>
+
+int A_constructed = 0;
+
+struct A
+{
+    int data_;
+public:
+    explicit A(int i) : data_(i) {++A_constructed;}
+
+    A(const A& a) : data_(a.data_)  {++A_constructed;}
+    ~A() {--A_constructed; data_ = 0;}
+
+    bool operator==(int i) const {return data_ == i;}
+};
+
+int main()
+{
+#if __cplusplus >= 201402L
+    typedef std::aligned_storage<3*sizeof(A), std::alignment_of<A>::value>::type
+            Storage;
+    Storage buffer;
+    std::raw_storage_iterator<A*, A> it((A*)&buffer);
+    assert(A_constructed == 0);
+    assert(it.base() == (A*)&buffer);
+    for (int i = 0; i < 3; ++i)
+    {
+        *it++ = A(i+1);
+        A* ap = (A*)&buffer + i;
+        assert(*ap == i+1);
+        assert(A_constructed == i+1);
+        assert(it.base() == ap + 1);  // next place to write
+    }
+#endif
+}