bug msvc2008/msvc2010 ? unable to match function definition to an existing declaration

struct dummy;
 
template <bool, class = void>
struct if_ {};
 
template <class t> 
struct if_<true, t> { typedef t type; };
 
template <class t, class u>
struct same_ { enum { value = 0 }; };
 
template <class t>
struct same_ <t,t> { enum { value = 1 }; };
 
#define impl(t,u) \
    typename if_< ! same_<t,u>::value, dummy*>::type
 
#define decl(t,u) \
    impl(t,u) = 0
 
struct example
{
    template<class A>
    example(const A&, decl(A, example) );
    example(const example&);
    example();        
};
 
template<class A>
example::example(const A&, impl(A, example) )
{}
 
int main(){}

struct dummy;
 
template <bool, class = void>
struct if_ {};
 
template <class t> 
struct if_<true, t> { typedef t type; };
 
template <class t, class u>
struct same_ { enum { value = 0 }; };
 
template <class t>
struct same_ <t,t> { enum { value = 1 }; };
 
template<class t, class u> struct help_
{
    enum { v = same_<t,u>::value };
    typedef if_<!v, dummy*>
        if_t;
    typedef typename if_t::type
        type;
};
 
#define impl(t,u) \
    typename help_<t,u>::type
 
#define decl(t,u) \
    impl(t,u) = 0
 
struct example
{
    template<class A>
    example(const A&, decl(A, example) );
    example(const example&);
    example();        
};
 
template<class A>
example::example(const A& a, impl(A, example) )
{}
 
int main(){}

template<class t, class u, bool = same_<t,u>::value> 
struct help_;
 
template<class t, class u> struct help_ <t, u, false>
    { typedef dummy* type; };