Pointer to member function template parameter in Visual Studio 2013

I came across a corner case and was looking for a job. I'm pretty sure this is a compiler error and I couldn't think of anything. I have a class that does not necessarily require a pointer to a member function. To make it optional, I made the default nullptr. It worked until I made unrelated changes. Visual studio now runs "Invalid template argument, expected compile-time constant". He still works for GCC. Here's an example:

template<class Key_, 
         class Value_, 
         Key_ (Value_::*KeyFn_)() const = nullptr, 
         template <class ...> class Map_ = std::map>
class Hashmap { ... }

      

        
        
        
      

    

Doesn't work here

template<class Key_, 
         class Value_, 
         Key_ (Value_::*KeyFn_)() const = nullptr, 
         template <class ...> class Map_ = std::map, 
         class Comparator_=std::less<Key_>>
class Hashmap { ... }

      

        
        
        
      

    

For some reason, I cannot break extracting keys from a type, so despite the temptation to provide keyfn in the constructor, this is not possible. The second version fails if KeyFn_ is nullptr (or 0). If I give a class member for it, it just compiles.

The complete source code is also available:

http://sourceforge.net/p/gorgon-ge/code/ci/gscript/tree/

working revision:

http://sourceforge.net/p/gorgon-ge/code/ci/77d287af75c2301fce55ab97ba49362f7ef6d9e0/tree/

I'm looking for either a job or an explanation if it shouldn't work at all.