mp_units::operator==

template<
    std::derived_from<quantity> Q,
    auto R2,
    typename Rep2>
requires requires { typename std::common_type_t<quantity, quantity<R2, Rep2>>; } &&
             std::equality_comparable<typename std::common_type_t<quantity, quantity<R2, Rep2>>::rep>
[[nodiscard]]
constexpr
bool
operator==(
    Q const& lhs,
    quantity<R2, Rep2> const& rhs);