https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106026
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reduced to:
```
struct k {
template <typename CPO, typename... Args>
auto operator()(CPO cpo, Args &&...args) const
-> decltype(tag_invoke(cpo, args...))
{
return tag_invoke(cpo, args...);
}
};
k j{};
struct nn {
template <class T>
friend void tag_invoke(nn, T &&) { }
auto operator()(auto x) const {
return j(*this, x);
}
};
constexpr nn h;
template <class T> concept has_extents = requires(T t) { h(t); };
template <has_extents T> constexpr void tag_invoke(nn, T &&) {}
static_assert(has_extents<int>);
```
