Conflicting declaration using constexpr and auto in C++11

I'm experimenting with C++11, constexpr and auto.

I'm failing to understand why this code does not compile:

  template<class T, T t>
  struct TestEle2
    {

    };

template<class T, T t>
  struct DStruct {int a;};

  template<char t>
  struct TestEle2<char, t>
    {
    static constexpr auto f = std::make_tuple(222/*
                                &DStruct<char, t>::a*/);

    static constexpr auto g = std::make_tuple(&DStruct<char, t>::a);
    };

  template<char c>
  constexpr decltype(TestEle2<char, c>::f)
    TestEle2<char, c>::f ; // This compiles

  template<char c>
  constexpr decltype(TestEle2<char, c>::f)
    TestEle2<char, c>::g ; // This does not compile

Without definition I have linking problems. I know this problem has been fixed in C++17 but better understand fully C++11 now