Hi,

I am trying to implement a histogram class that will be able to store tuples of any data type. Most likely, I chose std::tuple for the job. So, in brief I used std::tuple as the key type in an unordered_map. I used boost::hash_value to supply the hasher in place of std::hash in the third template argument to unordered_map.

Now, fast forwarding to my problem, I want to be able to provide a sub-histogram based on a few axes of the histogram. The code below, quite similar to what I want, refuses to work with msvc-14.0 (coming to it shortly).

----Sample Code----

#include <boost/mp11.hpp>
template<typename... T>
struct histogram {
    using type_list = boost::mp11::mp_list<T...>;

    template<std::size_t... D>
    void d() {

        // Error in below line

        histogram<boost::mp11::mp_at_c<type_list, D>...> f;
    }
};
int main() {
    histogram<int, int, int, int> f;
    f.d<1,2>();
    return 0;
}

---END---

So, msvc-14.0 gives the error (after tracing to the last function call in stack) at the position specified above. The error message which is coming from the AppVeyor logs (since I do not have msvc-14.0)

...