Decay optional type

decay_optional.hpp

template<typename T>
struct decay_optional {
  using type = T;
};

template<typename T>
struct decay_optional<std::optional<T>> {
  using type = T;
};

template<typename T>
struct decay_optional<boost::optional<T>> {
  using type = T;
};

template<typename T>
using decay_optional_t = typename decay_optional<T>::type;

static_assert(std::is_same_v<decay_optional_t<std::byte>, std::byte>);
static_assert(std::is_same_v<decay_optional_t<std::optional<std::byte>>, std::byte>);