[Bug c++/56749] New: weird interaction between scoped enum used as non-type template parameter and template lookup

[abigagli at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56749

             Bug #: 56749
           Summary: weird interaction between scoped enum used as non-type
                    template parameter and template lookup
    Classification: Unclassified
           Product: gcc
           Version: 4.8.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: abigagli@gmail.com


Hi, g++-4.81 built from svn r197010 on x86_64-apple-darwin12.3.0 with clang3.2.
I find the following unexpected:


enum normal_enum
{
    not_scoped1,
    not_scoped2
};

enum class scoped_enum
{
    scoped1,
    scoped2
};

template <normal_enum N=not_scoped1>
class A
{
public:
    template <typename T>
        void fun ()
        {
        }
};

template <scoped_enum N=scoped_enum::scoped1>
class B
{
public:
    template <typename T>
        void fun ()
        {
        }
};


template <typename T>
void tfun ()
{
    A<> a;
    a.fun<char>(); <------------ THIS IS FINE

    B<> b_defaulted;
    B<scoped_enum::scoped1> b_explicited;

    //b_defaulted.fun<char>();          <------------ UNEXPECTED: THIS FAILS 
    b_defaulted.template fun<char>();   <------------ THIS IS FINE

    //b_explicited.fun<char>();         <------------ UNEXPECTED: THIS FAILS 
    b_explicited.template fun<char>();  <------------ THIS IS FINE
}

int main(int argc, char const *argv[])
{
    tfun<int>();
    return 0;
}


IOW, it seems like using a scoped enum as a non-type template for a class,
induces  a requirement for template disambiguation when invoking a member
template which is not happpening using an normal enum.
Note that neither gcc 4.7.2 nor clang have this behavior.
I assume this is not expected, as I would say "fun" is never a dependent name
in the snippet above as neither a, b_defaulted and b_eplicited are, regardless
of using a scoped enum or a normal enum as the non-type template.

Regards,
Andrea Bigagli.