[Bug c++/46778] More SFINAE issues?

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46778

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2010-12-03 
11:32:00 UTC ---
the test looks valid to me, this simpler version is also rejected

template<typename _Tp>
  class is_constructible_mini2
  {
    typedef char __one;
    typedef struct { char __arr[2]; } __two;

    template<typename _Tp1>
      static decltype(_Tp1(), __one())
      __test(int);

    template<typename>
      static __two __test(...);

  public:
    static const bool value = sizeof(__test<_Tp>(0)) == 1;
  };

int t1[is_constructible_mini2<int&>::value ? -1 : 1];
int t2[is_constructible_mini2<const int&>::value ? -1 : 1];