mp_units::value_cast

template<
    typename ToRep,
    Unit auto ToU,
    typename FwdQ,
    RoundingPolicy Policy = truncated_t,
    Quantity Q = std::remove_cvref_t<FwdQ>>
requires UnitOf<MP_UNITS_REMOVE_CONST(decltype(ToU)), Q::quantity_spec> &&
           RepresentationOf<ToRep, Q::quantity_spec> && std::constructible_from<ToRep, typename Q::rep> &&
           detail::ExplicitlyCastable<Q::unit, ToU, ToRep> &&
           detail::ValidRoundingPolicyFor<Policy, typename Q::rep, ToRep>
[[nodiscard]]
constexpr
Quantity auto
value_cast(
    FwdQ&& q,
    Policy policy = Policy{});