Is noexcept deduction allowed in class template partial specialization?

For the program below, Clang 5 (trunk) reports that IsNoexcept is not deducible, while GCC 7.1 segfaults. What does the standard (draft) say about this? Is this a compiler QOI issue?

static_assert(__cpp_noexcept_function_type, "requires c++1z");

template<typename T>
struct is_noexcept;

template<bool IsNoexcept>
struct is_noexcept<void() noexcept(IsNoexcept)> {
    static constexpr auto value = IsNoexcept;
};

static_assert(is_noexcept<void() noexcept>::value);
static_assert(!is_noexcept<void()>::value);

int main() {}

Relates to proposal P0012.