Definition of Forward Declared Template Function Specialization

Question

How to match that forward declared specialized template function for definition. Its only a min dummy-Class and Hash and shouldn't be of concern here. Thank you for any suggestions that solve my template issue...

#include <iostream>
#include <string>
#include <memory>

class DummyC;
namespace std {
    template<> struct std::hash<DummyC> {
        std::size_t operator()(std::shared_ptr<DummyC>&) const noexcept; }; }

#include <unordered_map>

struct DummyC{
    std::string name;
    DummyC(const std::string& n =""):name{n}{}
    bool operator ==(const DummyC& s){ return (name==s.name); }
//  DummyC():name
};

namespace std {
    template<>
        std::size_t std::hash<DummyC>::operator()(std::shared_ptr<DummyC> &d) const noexcept{
            std::size_t pH = std::hash<unsigned long>{}(reinterpret_cast<unsigned long>(d.get()));
            std::size_t nH = std::hash<std::string>{}(d->name);
            return nH ^ ((pH%13) & (pH>>2));
        }
}

using namespace std;
int main(){
    auto t{ make_shared<DummyC>("Dope") };
    unordered_map<shared_ptr<DummyC>,int,hash<shared_ptr<DummyC>>> tmap{{t, 50}};
    for (const auto& i: tmap) cout<<'|'<<i.first->name<<'>'<<i.second<<"|\n";
}

The error message I'm getting is

hT.cpp:23:34: error: no function template matches function template specialization 'operator()'
        std::size_t std::hash<DummyC>::operator()(std::shared_ptr<DummyC> &d) const noexcept{

Answer 1

..so just for the record and anybody looking for similar, thats the cleaned up version thanks to Igor, Paddy and WCraig

#include <iostream>
#include <string>
#include <memory>

struct DummyC;
    template<> struct std::hash<std::shared_ptr<DummyC>> {
        std::size_t operator()(std::shared_ptr<DummyC> const &) const noexcept; };

#include <unordered_map>

struct DummyC{
    std::string name;
    DummyC(const std::string& n =""):name{n}{}
    bool operator ==(const DummyC& s){ return (name==s.name); }
};

    std::size_t std::hash<std::shared_ptr<DummyC>>::operator()(std::shared_ptr<DummyC> const &d) const noexcept{
        std::size_t pH = std::hash<void*>{}(reinterpret_cast<void*>(d.get()));
        std::size_t nH = std::hash<std::string>{}(d->name);
        return nH ^ ((pH%13) & (pH>>2));
    }

using namespace std;
int main(){
    auto t{ make_shared<DummyC>("Dope") };
    unordered_map<shared_ptr<DummyC>,int,hash<shared_ptr<DummyC>>> tmap{{t, 50}};
    for (const auto& i: tmap) cout<<'|'<<i.first->name<<'>'<<i.second<<"|\n";
}