[Bug c++/50034] New: Overload selection failure within class template

["crowl at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50034

             Bug #: 50034
           Summary: Overload selection failure within class template
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: crowl@gcc.gnu.org


The following code fails to compile with
g++ (GCC) 4.7.0 20110809 (experimental) [trunk revision 177606]

template <typename From, typename To>
class implicit {
 private:
 static From from_type();
 static char selector(To);
 static char (&selector(...))[2];
 public:
 static const bool value = sizeof(selector(implicit::from_type())) == 1;
};

template <typename From, typename To>
const bool implicit<From, To>::value;

class abstract {
 virtual void pure() = 0;
 abstract(const abstract&);
};

int main() {
 return implicit<const abstract&, long long int>::value;
}

# Note that I am not using C++0x.
g++ -c implicit.cc
implicit.cc: In instantiation of 'const bool implicit<const abstract&,
long long int>::value':
implicit.cc:20:54:   required from here
implicit.cc:16:3: error: 'abstract::abstract(const abstract&)' is private
implicit.cc:8:72: error: within this context
implicit.cc:8:72: error: cannot allocate an object of abstract type 'abstract'
implicit.cc:14:7: note:   because the following virtual functions are
pure within 'abstract':
implicit.cc:15:16: note:        virtual void abstract::pure()