From cd0ee9276b41bc28e1648479c4b25cb4864f97a0 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Fri, 3 Feb 2023 15:22:54 +0100
Subject: [PATCH] feat: `quantity_cast` and multiplying by reference now use
 perfect forwarding of a number

---
 src/core/include/mp_units/bits/quantity_cast.h | 10 +++++-----
 src/core/include/mp_units/reference.h          |  4 ++--
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/core/include/mp_units/bits/quantity_cast.h b/src/core/include/mp_units/bits/quantity_cast.h
index 2654842f..70ae64af 100644
--- a/src/core/include/mp_units/bits/quantity_cast.h
+++ b/src/core/include/mp_units/bits/quantity_cast.h
@@ -55,12 +55,12 @@ class quantity;
  *
  * @tparam ToQS a quantity specification to use for a target quantity
  */
-template<QuantitySpec auto ToQ, auto R, typename Rep>
-  requires(interconvertible(ToQ, get_quantity_spec(R)))
-[[nodiscard]] constexpr Quantity auto quantity_cast(const quantity<R, Rep>& q)
+template<QuantitySpec auto ToQS, Quantity Q>
+  requires(interconvertible(ToQS, get_quantity_spec(Q::reference)))
+[[nodiscard]] constexpr Quantity auto quantity_cast(Q&& q)
 {
-  constexpr reference<ToQ, quantity<R, Rep>::unit> r;
-  return q.count() * r;
+  constexpr reference<ToQS, Q::unit> r;
+  return std::forward<Q>(q).number() * r;
 }
 
 }  // namespace mp_units
diff --git a/src/core/include/mp_units/reference.h b/src/core/include/mp_units/reference.h
index b4b08721..f03091b9 100644
--- a/src/core/include/mp_units/reference.h
+++ b/src/core/include/mp_units/reference.h
@@ -159,9 +159,9 @@ template<AssociatedUnit U1, auto Q2, auto U2>
 }
 
 template<Reference R, RepresentationOf<get_quantity_spec(R{}).character> Rep>
-[[nodiscard]] constexpr quantity<R{}, Rep> operator*(const Rep& lhs, R)
+[[nodiscard]] constexpr quantity<R{}, Rep> operator*(Rep&& lhs, R)
 {
-  return quantity<R{}, Rep>(lhs);
+  return quantity<R{}, Rep>(std::forward<Rep>(lhs));
 }
 
 void /*Use `q * (1 * r)` rather than `q * r`.*/ operator*(Quantity auto, Reference auto) = delete;