template <class Y> struct auto_ptr_ref;
Reference to automatic pointer
This is an instrumental class to allow certain conversions that allow auto_ptr objects to be passed to and returned from functions.
The class has no members other than holding a reference to an auto_ptr object.
C++11, which deprecates the use of auto_ptr, also introduces flexibility on whether a library shall implement a class with this name or provide the same functionality in some other way.