Why is partial specialization of a nested class template allowed, while complete isn't?

Question

    template struct A {                                                                                                    
        template

        

Answer 1

Backing up Virgil's argument (he was faster than I posting the same rationale), consider this:

template
class TOuter
  {
  public:
    template
    class TInner
      {
      public:
        T1 m_1;
        T2 m_2;
      };
  };

template
template<>
class TOuter::TInner
  {
  public:
    T1    m_1;
    float m_2;
 };

Is TInner fully specialized, or partially specialized because of T1?

Edit:

After considering some of the other comments - it seems that you want to have a full specialization based on the template parameter in the outer class. If you nest the inner class's implementation, that seems to work in Visual Studio 2005:

template
class TOuter
  {
  public:
    template
    class TInner
      {
      public:
        std::string DoSomething() { return "Inner - general"; }
        T2 m_2;
      };

    template<>
    class TInner
      {
      public:
        std::string DoSomething() { return "Inner - special"; }
        T1 m_1;
      };
  };

TOuter::TInner will correctly be the specialization of TInner. I could not get it to compile with the implementation outside of the template.