Partial specialization of single type template parameter class template using non-type template parameter through a dependent type

_{All standard references below refers to N4659: March 2017 post-Kona working draft/C++17 DIS.}

Consider the following snippet:

#include <type_traits>

template <int N> struct num {};

template <typename> struct A;

// (1)
template <int N> struct A<num<N>> { using type = bool; };

// (2)
template <long N> struct A<num<N>> { using type = char; };

static_assert(!std::is_same_v<long, int>, "");

// (A)
static_assert(std::is_same_v<A<num<1>>::type, bool>, "");

int main() {}

The static_assert at (A) is successful for GCC, but fails for Clang:

error: static_assert failed due to 
       requirement 'std::is_same_v<char, bool>' ""

Essentially, GCC picks the perfectly matching specialization (1), whereas Clang picks the specialization (2).

Similarly, if we remove the assertions as well as specialization (1):

template <int N> struct num {};

template <typename> struct A;

// (2)
template <long N> struct A<num<N>> { using type = char; };

int main() {
  A<num<1>> a{};
  (void)a;
}

Then GCC fails to compile the program whereas Clang accepts it.

GCC:

error: variable '`A<num<1> > a`' has initializer but incomplete type

This behaviour holds over various GCC and Clang versions, as well as various C++ language levels over these version (C++11, C++14, C++17, C++2a).

Question

• Is the first snippet above in fact ill-formed (no diagnostic required?), or is either GCC or Clang wrong?

My guess is that this is ill-formed, but haven't been able to apply a relevant part of [temp.class.spec] to reject it. Perhaps [temp.class.spec]/8.1?

[temp.class.spec]/8.1 The type of a template parameter corresponding to a specialized non-type argument shall not be dependent on a parameter of the specialization. [ Example: [...] — end example ]