std::hash template partial specialization

Question

I wrote some class with template:

 template  >
 class my_list;

I should write ::st

Answer 1

The paragraph you're quoting does not apply. You're partialy specialising a class template (std::hash), not a member class template of a standard library class or class template. std::hash is not a member of any class or class template.

For your case, paragraph 1 of the same section applies, and that allows specialisation when at least one user-defined type is involved (emphasis mine):

The behavior of a C++ program is undefined if it adds declarations or definitions to namespace std or to a namespace within namespace std unless otherwise specified. A program may add a template specialization for any standard library template to namespace std only if the declaration depends on a user-defined type and the specialization meets the standard library requirements for the original template and is not explicitly prohibited.