https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114349
--- Comment #5 from Sam James <sjames at gcc dot gnu.org> ---
>From my overnight run, just for completeness:
```
struct a {};
template <int> using b = a;
template <template <typename> class, typename, typename> using c = a;
template <typename g> using d = g;
template <class> constexpr int e(b<1>) { return 1; }
template <class f> struct o {
void operator=(o) noexcept(e<f>(c<d, int, b<1>>{}));
};
template <typename, typename, typename> using h = o<int>;
template <typename i, typename j, typename k = i> using l = h<i, j, k>;
l<int, int> m, n;
void p() { m = n; }
```
