[Bug c++/67605] New: Compilation errors creating std::pair using templated arguments

[kplatz at utdallas dot edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67605

            Bug ID: 67605
           Summary: Compilation errors creating std::pair using templated
                    arguments
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kplatz at utdallas dot edu
  Target Milestone: ---

The following code compiles correctly on the GCC-4.8 series, but errors out on
GCC-4.9 and 5.X:

#include <algorithm>
#include <utility>

template<int K> class List;

template<int K>
class List  {
    template<int KK>
    class Node {
    public:
        static const int SPLIT;
        Node<KK>* next;            // Next pointer
        int keys[KK];       // Set of key/data pairs.

        Node() : next(nullptr) {
            std::fill(keys, keys + KK, 0); 
        }
    };

public:
    std::pair<Node<K>*, Node<K>*> scan();
};

template <int K>
std::pair<List<K>::Node<K>*, List<K>::Node<K>*> List<K>::scan( ) {
    return std::make_pair( nullptr, nullptr );
}

int main() {
    List<1> foo;

    auto bar = foo.scan();
}

The errors reported are:
[ken@sager ~]$ g++520 --std=c++11 urllist1.cpp 
urllist1.cpp:32:26: error: wrong number of template arguments (1, should be 2)
 std::pair<List<K>::Node<K>*, List<K>::Node<K>*> List<K>::scan( ) {
                          ^
In file included from /usr/local/include/c++/5.2.0/utility:70:0,
                 from /usr/local/include/c++/5.2.0/algorithm:60,
                 from urllist1.cpp:8:
/usr/local/include/c++/5.2.0/bits/stl_pair.h:96:12: note: provided for
‘template<class _T1, class _T2> struct std::pair’
     struct pair
            ^
urllist1.cpp:32:28: error: expected unqualified-id before ‘,’ token
 std::pair<List<K>::Node<K>*, List<K>::Node<K>*> List<K>::scan( ) {