[Bug c++/60689] New: Bogus error with atomic::exchange

["roman at binarylife dot net" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60689

            Bug ID: 60689
           Summary: Bogus error with atomic::exchange
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: roman at binarylife dot net
              Host: x86_64-unknown-linux-gnu
            Target: x86_64-unknown-linux-gnu
             Build: x86_64-unknown-linux-gnu

$ cat test.cc 
#include <atomic>

template<int N>
struct X { char stuff[N]; };

template<int N>
void test() {
  X<N> x;
  std::atomic<X<N>> a;
  x = a;
  a.exchange(x);
}

int main() {
  test<9>();
  return 0;
}

$ g++ -std=c++11 -O2 -l atomic test.cc 
In file included from test.cc:1:0:
/home/abend/local/gcc-4.9/include/c++/4.9.0/atomic: In instantiation of â_Tp
std::atomic<_Tp>::exchange(_Tp, std::memory_order) [with _Tp = X<9>;
std::memory_order = std::memory_order]â:
test.cc:11:3:   required from âvoid test() [with int N = 9]â
test.cc:15:11:   required from here
/home/abend/local/gcc-4.9/include/c++/4.9.0/atomic:225:41: error: invalid
conversion from âX<9>*â to âlong unsigned intâ [-fpermissive]
  __atomic_exchange(&_M_i, &__i, &tmp, _m); 
                                         ^
/home/abend/local/gcc-4.9/include/c++/4.9.0/atomic:225:41: error: cannot
convert âstd::memory_orderâ to âvoid*â for argument â4â to âvoid
__atomic_exchange(long unsigned int, volatile void*, void*, void*, int)â

$ g++ --version
g++ (GCC) 4.9.0 20140327 (experimental)
...