VC++ cannot resolve function overload as template parameter by goffioul

When using function as template parameter, along with template overload with different function signatures, VC++ is unable to resolve the function template parameter correctly. The following piece of code illustrates the issue:

#include <cmath>
#include <complex>
#include <iostream>

template <class T>
class A
{
public:
        A (T t) : _t (t) { }
        A (const A& a) : _t (a._t) { }
        A& operator= (const A& a)
        {
                _t = a._t;
                return *this;
        }

        T val (void) const { return _t; }

private:
        T _t;
};

template <class R, class T, R fun (T)>
inline A<R> mapper (const A<T>& a)
{
        return A<R> (fun (a.val ()));
}

template <class R, class T, R fun (const T&)>
inline A<R> mapper (const A<T>& a)
{
        return A<R> (fun (a.val ()));
}

int main (int argc, char **argv)
{
        A<double> d (-1);
        A< std::complex<double> > c (std::complex<double> (1, 1));

        std::cout << d.val () << " -> " << mapper<double, double, std::abs> (d).val () << std::endl;
        std::cout << c.val () << " -> " << mapper<double, std::complex<double>, std::abs> (c).val () << std::endl;

        return 0;
}