Merge to upstream r225300.

Change-Id: I2b23715db9ac129ff80aa78ad5824db0a4d6fbb3

test/std/utilities/memory/pointer.traits/pointer.traits.functions/pointer_to.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.
+//
+//===----------------------------------------------------------------------===//
+
+// <memory>
+
+// template <class Ptr>
+// struct pointer_traits
+// {
+//     static pointer pointer_to(<details>);
+//     ...
+// };
+
+#include <memory>
+#include <cassert>
+
+template <class T>
+struct A
+{
+private:
+    struct nat {};
+public:
+    typedef T element_type;
+    element_type* t_;
+
+    A(element_type* t) : t_(t) {}
+
+    static A pointer_to(typename std::conditional<std::is_void<element_type>::value,
+                                           nat, element_type>::type& et)
+        {return A(&et);}
+};
+
+int main()
+{
+    {
+        int i = 0;
+        A<int> a = std::pointer_traits<A<int> >::pointer_to(i);
+        assert(a.t_ == &i);
+    }
+    {
+        (std::pointer_traits<A<void> >::element_type)0;
+    }
+}