mp_units::utility::detail::operator<=>

[[nodiscard]]
constexpr
auto
operator<=>(
    constrained<T, EP> const& lhs,
    constrained<U, EP> const& rhs);

[[nodiscard]]
constexpr
std::strong_ordering
operator<=>(
    safe_int<T, EP1> lhs,
    safe_int<U, EP2> rhs) noexcept;