mp_units::utility::detail::operator+

[[nodiscard]]
constexpr
safe_int<integral_op_result_t<T, U>, EP>
operator+(
    safe_int<T, EP> lhs,
    safe_int<U, EP> rhs);

[[nodiscard]]
constexpr
constrained<decltype(lhs.value_ + rhs.value_), EP>
operator+(
    constrained<T, EP> const& lhs,
    constrained<U, EP> const& rhs);