template struct rgpot::vesin_compat::has_n_threads_member<Options, std::void_t<decltype(std::declval<Options>().n_threads)>>

template <typename Options>
struct has_n_threads_member<Options, std::void_t<decltype(std::declval<Options>().n_threads)>>:
    public std::false_type,
    public std::true_type {
};