addressof misbehaving for type with an implicit conversion operator to char&.  This fixes http://llvm.org/bugs/show_bug.cgi?id=15754

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@179608 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/memory b/include/memory
index fe35238..87436ac 100644
--- a/include/memory
+++ b/include/memory
@@ -621,7 +621,7 @@
 _Tp*
 addressof(_Tp& __x) _NOEXCEPT
 {
-    return (_Tp*)&(char&)__x;
+    return (_Tp*)&reinterpret_cast<const volatile char&>(__x);
 }
 
 #if defined(_LIBCPP_HAS_OBJC_ARC) && !defined(_LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF)