[temp.spec.partial.member]

The members of the class template partial specialization are unrelated to the members of the primary template.

Class template partial specialization members that are used in a way that requires a definition shall be defined; the definitions of members of the primary template are never used as definitions for members of a class template partial specialization.

An explicit specialization of a member of a class template partial specialization is declared in the same way as an explicit specialization of a member of the primary template.

[Example 1: / primary class template template<class T, int I> struct A { void f(); }; / member of primary class template template<class T, int I> void A<T,I>::f() { } / class template partial specialization template<class T> struct A<T,2> { void f(); void g(); void h(); }; / member of class template partial specialization template<class T> void A<T,2>::g() { } / explicit specialization template<> void A<char,2>::h() { } int main() { A<char,0> a0; A<char,2> a2; a0.f(); / OK, uses definition of primary template's member a2.g(); / OK, uses definition of partial specialization's member a2.h(); / OK, uses definition of explicit specialization's member a2.f(); / error: no definition of f for A<T,2>; the primary template is not used here } — end example]

If a member template of a class template is partially specialized, the member template partial specializations are member templates of the enclosing class template; if the enclosing class template is instantiated ([temp.inst], [temp.explicit]), a declaration for every member template partial specialization is also instantiated as part of creating the members of the class template specialization.

If the primary member template is explicitly specialized for a given (implicit) specialization of the enclosing class template, the partial specializations of the member template are ignored for this specialization of the enclosing class template.

If a partial specialization of the member template is explicitly specialized for a given (implicit) specialization of the enclosing class template, the primary member template and its other partial specializations are still considered for this specialization of the enclosing class template.

[Example 2: template<class T> struct A { template<class T2> struct B {}; / #1 template<class T2> struct B<T2*> {}; / #2 }; template<> template<class T2> struct A<short>::B {}; / #3 A<char>::B<int*> abcip; / uses #2 A<short>::B<int*> absip; / uses #3 A<char>::B<int> abci; / uses #1 — end example]