Std::atomic_exchange return wrong pointer type

Question

I am using the following product:
Microsoft Visual Studio Professional 2013
Version 12.0.31101.00 Update 4
Given the following example:
#include <atomic>
#include <iostream>
std::atomic<int*> ptr = nullptr;
int desired = 5;
auto previous0 = std::atomic_exchange_explicit(&ptr, &desired, std::memory_order_acq_rel);
auto previous1 = std::atomic_exchange_explicit(&ptr, nullptr, std::memory_order_acq_rel);
auto previous2 = std::atomic_exchange(&ptr, &desired);
auto previous3 = std::atomic_exchange(&ptr, nullptr);
std::cout << typeid(previous0).name() << std::endl;
std::cout << typeid(previous1).name() << std::endl;
std::cout << typeid(previous2).name() << std::endl;
std::cout << typeid(previous3).name() << std::endl;
I get the output:
int *
void *
int *
void *
Expected output would be:
int *
int *
int *
int *
Is this a known bug in VC12?
PS: I couldn't find a proper category for MSVC related questions.

Answer 1

I see that it prefers:
inline _ITYPE atomic_exchange_explicit(
_ATOMIC_ITYPE *_Atom, _ITYPE _Value,
memory_order _Order) _NOEXCEPT
{ // exchange value stored in *_Atom with _Value
return _ATOMIC_EXCHANGE(_Atom, _Value, _Order);
over
template <class _Ty>
inline _Ty atomic_exchange_explicit(atomic<_Ty> *_Atom, _Ty _Value,
memory_order _Order) _NOEXCEPT
return _Atom->exchange(_Value, _Order);
That does seem a little suspicious.  I can't say for sure if that's a bug.
Of course, the easy workarounds are to either specify the template arguments or cast nullptr to the appropriate type.
auto previous1a = std::atomic_exchange_explicit<int*>(&ptr, nullptr, std::memory_order_acq_rel);
// or
auto previous1b = std::atomic_exchange_explicit(&ptr, (int*)nullptr, std::memory_order_acq_rel);