[Bug c++/96204] gcc complains about private member access in SFINAE context

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96204

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Reduced:

template<typename...> using void_t = void;

template<typename T> T&& declval();

template <typename, typename = void>
struct has_set_attr_method {
    static constexpr bool value = false;
};
template <typename T>
struct has_set_attr_method<T, void_t<decltype(declval<T>().setAttr(1))>> {
    static constexpr bool value = true;
};

struct Parent
{
    public:
        template<typename T>
            static bool create()    {   
                return has_set_attr_method<T>::value;
            }
};

struct Child : public Parent {
    public:
        friend class Parent;
    private:
        void setAttr(int) {
        }
};

int main() {
    Parent::create<Child>();
}