[Bug c++/92654] [8/9/10 Regression] internal compiler error: in lookup_template_class_1

[fiesh at zefix dot tv]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92654

--- Comment #7 from fiesh at zefix dot tv ---
And creduce just finished:  (I left the ifdef unchanged so it can still be
compiled under clang.)



#ifdef __has_builtin
#define a 1
#endif
template <typename b, b c> struct d {
  typedef b e;
  constexpr operator e() const { return c; }
};
template <typename> using g = int;
template <typename b, b...> struct h {};
template <typename b, b aa>
using i
#if a
    = __make_integer_seq<h, b, a>
#else
    = h<b, __integer_pack(aa)...>
#endif
    ;
template <typename j, typename ac, ac... ad> void ae(j f, h<ac, ad...>) {
  (f(d<ac, ad>{}), ...);
}
template <auto k, typename j> void af(j f) {
  using ac = g<decltype(k)>;
  using l = i<ac, k>;
  ae(f, l{});
}
template <typename m, m n> using o = d<m, n>;
template <typename ag, typename j> struct t {
  j f;
  template <typename u> void operator()(u) { f(o<ag, ag(0)>{}); }
};
template <typename ag, typename j> void ai(j f) {
  auto aj = t<ag, j>{f};
  af<p(ag{})>(aj);
}
enum q {};
constexpr int p(q) { return 2; }
enum r { s };
template <q, unsigned long> struct C;
template <r> int ak(int const &);
template <template <q, unsigned long, q, unsigned long> typename,
          template <q, unsigned long> typename al>
void am() {
  ai<q>([](auto an) {
    auto ao = decltype(an)();
    [ao](auto ad) {
      using u = decltype(ad);
      if constexpr (al<ao, u{}>::ap)
        ;
    };
  });
}
template <q, unsigned long, q, unsigned long> struct D;
template <> int ak<s>(int const &) { am<D, C>; }