How many specializations of class template with not-type template argument must become friends?

In the following code, there is template struct A with not-type template argument, and class B declares A<0> as its friend. Then the member function A<x>::has_access() is used to check that it has access to private B::p():

template<auto>
struct A {
    static constexpr bool has_access();
};

class B {
    void p() {}
    friend struct A<0>;
};

template<auto x>
constexpr bool A<x>::has_access() {
    return requires(B b) { b.p(); };
}

// #1: accepted by all
static_assert( A<0>::has_access() );
// #2: accepted by Clang
static_assert( A<1>::has_access() );
// #3: accepted by Clang and MSVC
static_assert( A<char(0)>::has_access() );

The program acceptance diverges:

1. A<0>::has_access() is true in all compilers I tested.
2. A<1>::has_access() is true in Clang only.
3. A<char(0)>::has_access() is true in Clang and MSVC only.

Demo: https://gcc.godbolt.org/z/P5njvzGee

Which compiler is right here? How many specializations of A must become friends of B after friend struct A<0>?