refactor: binary operators of quantity and quantity_point are now hidden friends

src/core/include/mp-units/framework/quantity.h

@@ -461,6 +461,115 @@ public:
     lhs.numerical_value_is_an_implementation_detail_ /= rhs.numerical_value_is_an_implementation_detail_;
     return std::forward<Q1>(lhs);
   }
+
+  // binary operators on quantities
+  template<auto R2, typename Rep2>
+    requires detail::CommonlyInvocableQuantities<std::plus<>, quantity, quantity<R2, Rep2>>
+  [[nodiscard]] friend constexpr Quantity auto operator+(const quantity& lhs, const quantity<R2, Rep2>& rhs)
+  {
+    using ret = detail::common_quantity_for<std::plus<>, quantity, quantity<R2, Rep2>>;
+    const ret ret_lhs(lhs);
+    const ret ret_rhs(rhs);
+    return ::mp_units::quantity{ret_lhs.numerical_value_ref_in(ret::unit) + ret_rhs.numerical_value_ref_in(ret::unit),
+                                ret::reference};
+  }
+
+  template<auto R2, typename Rep2>
+    requires detail::CommonlyInvocableQuantities<std::minus<>, quantity, quantity<R2, Rep2>>
+  [[nodiscard]] friend constexpr Quantity auto operator-(const quantity& lhs, const quantity<R2, Rep2>& rhs)
+  {
+    using ret = detail::common_quantity_for<std::minus<>, quantity, quantity<R2, Rep2>>;
+    const ret ret_lhs(lhs);
+    const ret ret_rhs(rhs);
+    return ::mp_units::quantity{ret_lhs.numerical_value_ref_in(ret::unit) - ret_rhs.numerical_value_ref_in(ret::unit),
+                                ret::reference};
+  }
+
+  template<auto R2, typename Rep2>
+    requires(!treat_as_floating_point<Rep>) && (!treat_as_floating_point<Rep2>) &&
+            detail::CommonlyInvocableQuantities<std::modulus<>, quantity, quantity<R2, Rep2>>
+  [[nodiscard]] friend constexpr Quantity auto operator%(const quantity& lhs, const quantity<R2, Rep2>& rhs)
+  {
+    MP_UNITS_EXPECTS_DEBUG(rhs != rhs.zero());
+    using ret = detail::common_quantity_for<std::modulus<>, quantity, quantity<R2, Rep2>>;
+    const ret ret_lhs(lhs);
+    const ret ret_rhs(rhs);
+    return ::mp_units::quantity{ret_lhs.numerical_value_ref_in(ret::unit) % ret_rhs.numerical_value_ref_in(ret::unit),
+                                ret::reference};
+  }
+
+  template<auto R2, typename Rep2>
+    requires detail::InvocableQuantities<std::multiplies<>, quantity, quantity<R2, Rep2>>
+  [[nodiscard]] friend constexpr Quantity auto operator*(const quantity& lhs, const quantity<R2, Rep2>& rhs)
+  {
+    return ::mp_units::quantity{lhs.numerical_value_ref_in(get_unit(R)) * rhs.numerical_value_ref_in(get_unit(R2)),
+                                R * R2};
+  }
+
+  template<typename Value>
+    requires(!Quantity<Value>) && (!Reference<Value>) &&
+            detail::InvokeResultOf<get_quantity_spec(R).character, std::multiplies<>, Rep, const Value&>
+  [[nodiscard]] friend constexpr QuantityOf<get_quantity_spec(R)> auto operator*(const quantity& q, const Value& v)
+  {
+    return ::mp_units::quantity{q.numerical_value_ref_in(get_unit(R)) * v, R};
+  }
+
+  template<typename Value>
+    requires(!Quantity<Value>) && (!Reference<Value>) &&
+            detail::InvokeResultOf<get_quantity_spec(R).character, std::multiplies<>, const Value&, Rep>
+  [[nodiscard]] friend constexpr QuantityOf<get_quantity_spec(R)> auto operator*(const Value& v, const quantity& q)
+  {
+    return ::mp_units::quantity{v * q.numerical_value_ref_in(get_unit(R)), R};
+  }
+
+  template<auto R2, typename Rep2>
+    requires detail::InvocableQuantities<std::divides<>, quantity, quantity<R2, Rep2>>
+  [[nodiscard]] friend constexpr Quantity auto operator/(const quantity& lhs, const quantity<R2, Rep2>& rhs)
+  {
+    MP_UNITS_EXPECTS_DEBUG(rhs != rhs.zero());
+    return ::mp_units::quantity{lhs.numerical_value_ref_in(get_unit(R)) / rhs.numerical_value_ref_in(get_unit(R2)),
+                                R / R2};
+  }
+
+  template<typename Value>
+    requires(!Quantity<Value>) && (!Reference<Value>) &&
+            detail::InvokeResultOf<get_quantity_spec(R).character, std::divides<>, Rep, const Value&>
+  [[nodiscard]] friend constexpr QuantityOf<get_quantity_spec(R)> auto operator/(const quantity& q, const Value& v)
+  {
+    MP_UNITS_EXPECTS_DEBUG(v != quantity_values<Value>::zero());
+    return ::mp_units::quantity{q.numerical_value_ref_in(get_unit(R)) / v, R};
+  }
+
+  template<typename Value>
+    requires(!Quantity<Value>) && (!Reference<Value>) &&
+            detail::InvokeResultOf<get_quantity_spec(R).character, std::divides<>, const Value&, Rep>
+  [[nodiscard]] friend constexpr QuantityOf<inverse(get_quantity_spec(R))> auto operator/(const Value& v,
+                                                                                          const quantity& q)
+  {
+    return ::mp_units::quantity{v / q.numerical_value_ref_in(get_unit(R)), ::mp_units::one / R};
+  }
+
+  template<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]] friend constexpr bool operator==(const quantity& lhs, const quantity<R2, Rep2>& rhs)
+  {
+    using ct = std::common_type_t<quantity, quantity<R2, Rep2>>;
+    const ct ct_lhs(lhs);
+    const ct ct_rhs(rhs);
+    return ct_lhs.numerical_value_ref_in(ct::unit) == ct_rhs.numerical_value_ref_in(ct::unit);
+  }
+
+  template<auto R2, typename Rep2>
+    requires requires { typename std::common_type_t<quantity, quantity<R2, Rep2>>; } &&
+             std::three_way_comparable<typename std::common_type_t<quantity, quantity<R2, Rep2>>::rep>
+  [[nodiscard]] friend constexpr auto operator<=>(const quantity& lhs, const quantity<R2, Rep2>& rhs)
+  {
+    using ct = std::common_type_t<quantity, quantity<R2, Rep2>>;
+    const ct ct_lhs(lhs);
+    const ct ct_rhs(rhs);
+    return ct_lhs.numerical_value_ref_in(ct::unit) <=> ct_rhs.numerical_value_ref_in(ct::unit);
+  }
 };
 
 // CTAD
@@ -473,113 +582,6 @@ explicit(
   is_specialization_of<decltype(quantity_like_traits<Q>::to_numerical_value(std::declval<Q>())), convert_explicitly>)
   quantity(Q) -> quantity<quantity_like_traits<Q>::reference, typename quantity_like_traits<Q>::rep>;
 
-// binary operators on quantities
-template<auto R1, typename Rep1, auto R2, typename Rep2>
-  requires detail::CommonlyInvocableQuantities<std::plus<>, quantity<R1, Rep1>, quantity<R2, Rep2>>
-[[nodiscard]] constexpr Quantity auto operator+(const quantity<R1, Rep1>& lhs, const quantity<R2, Rep2>& rhs)
-{
-  using ret = detail::common_quantity_for<std::plus<>, quantity<R1, Rep1>, quantity<R2, Rep2>>;
-  const ret ret_lhs(lhs);
-  const ret ret_rhs(rhs);
-  return quantity{ret_lhs.numerical_value_ref_in(ret::unit) + ret_rhs.numerical_value_ref_in(ret::unit),
-                  ret::reference};
-}
-
-template<auto R1, typename Rep1, auto R2, typename Rep2>
-  requires detail::CommonlyInvocableQuantities<std::minus<>, quantity<R1, Rep1>, quantity<R2, Rep2>>
-[[nodiscard]] constexpr Quantity auto operator-(const quantity<R1, Rep1>& lhs, const quantity<R2, Rep2>& rhs)
-{
-  using ret = detail::common_quantity_for<std::minus<>, quantity<R1, Rep1>, quantity<R2, Rep2>>;
-  const ret ret_lhs(lhs);
-  const ret ret_rhs(rhs);
-  return quantity{ret_lhs.numerical_value_ref_in(ret::unit) - ret_rhs.numerical_value_ref_in(ret::unit),
-                  ret::reference};
-}
-
-template<auto R1, typename Rep1, auto R2, typename Rep2>
-  requires(!treat_as_floating_point<Rep1>) && (!treat_as_floating_point<Rep2>) &&
-          detail::CommonlyInvocableQuantities<std::modulus<>, quantity<R1, Rep1>, quantity<R2, Rep2>>
-[[nodiscard]] constexpr Quantity auto operator%(const quantity<R1, Rep1>& lhs, const quantity<R2, Rep2>& rhs)
-{
-  MP_UNITS_EXPECTS_DEBUG(rhs != rhs.zero());
-  using ret = detail::common_quantity_for<std::modulus<>, quantity<R1, Rep1>, quantity<R2, Rep2>>;
-  const ret ret_lhs(lhs);
-  const ret ret_rhs(rhs);
-  return quantity{ret_lhs.numerical_value_ref_in(ret::unit) % ret_rhs.numerical_value_ref_in(ret::unit),
-                  ret::reference};
-}
-
-template<auto R1, typename Rep1, auto R2, typename Rep2>
-  requires detail::InvocableQuantities<std::multiplies<>, quantity<R1, Rep1>, quantity<R2, Rep2>>
-[[nodiscard]] constexpr Quantity auto operator*(const quantity<R1, Rep1>& lhs, const quantity<R2, Rep2>& rhs)
-{
-  return quantity{lhs.numerical_value_ref_in(get_unit(R1)) * rhs.numerical_value_ref_in(get_unit(R2)), R1 * R2};
-}
-
-template<auto R, typename Rep, typename Value>
-  requires(!Quantity<Value>) && (!Reference<Value>) &&
-          detail::InvokeResultOf<get_quantity_spec(R).character, std::multiplies<>, Rep, const Value&>
-[[nodiscard]] constexpr QuantityOf<get_quantity_spec(R)> auto operator*(const quantity<R, Rep>& q, const Value& v)
-{
-  return quantity{q.numerical_value_ref_in(get_unit(R)) * v, R};
-}
-
-template<typename Value, auto R, typename Rep>
-  requires(!Quantity<Value>) && (!Reference<Value>) &&
-          detail::InvokeResultOf<get_quantity_spec(R).character, std::multiplies<>, const Value&, Rep>
-[[nodiscard]] constexpr QuantityOf<get_quantity_spec(R)> auto operator*(const Value& v, const quantity<R, Rep>& q)
-{
-  return quantity{v * q.numerical_value_ref_in(get_unit(R)), R};
-}
-
-template<auto R1, typename Rep1, auto R2, typename Rep2>
-  requires detail::InvocableQuantities<std::divides<>, quantity<R1, Rep1>, quantity<R2, Rep2>>
-[[nodiscard]] constexpr Quantity auto operator/(const quantity<R1, Rep1>& lhs, const quantity<R2, Rep2>& rhs)
-{
-  MP_UNITS_EXPECTS_DEBUG(rhs != rhs.zero());
-  return quantity{lhs.numerical_value_ref_in(get_unit(R1)) / rhs.numerical_value_ref_in(get_unit(R2)), R1 / R2};
-}
-
-template<auto R, typename Rep, typename Value>
-  requires(!Quantity<Value>) && (!Reference<Value>) &&
-          detail::InvokeResultOf<get_quantity_spec(R).character, std::divides<>, Rep, const Value&>
-[[nodiscard]] constexpr QuantityOf<get_quantity_spec(R)> auto operator/(const quantity<R, Rep>& q, const Value& v)
-{
-  MP_UNITS_EXPECTS_DEBUG(v != quantity_values<Value>::zero());
-  return quantity{q.numerical_value_ref_in(get_unit(R)) / v, R};
-}
-
-template<typename Value, auto R, typename Rep>
-  requires(!Quantity<Value>) && (!Reference<Value>) &&
-          detail::InvokeResultOf<get_quantity_spec(R).character, std::divides<>, const Value&, Rep>
-[[nodiscard]] constexpr QuantityOf<inverse(get_quantity_spec(R))> auto operator/(const Value& v,
-                                                                                 const quantity<R, Rep>& q)
-{
-  return quantity{v / q.numerical_value_ref_in(get_unit(R)), ::mp_units::one / R};
-}
-
-template<auto R1, typename Rep1, auto R2, typename Rep2>
-  requires requires { typename std::common_type_t<quantity<R1, Rep1>, quantity<R2, Rep2>>; } &&
-           std::equality_comparable<typename std::common_type_t<quantity<R1, Rep1>, quantity<R2, Rep2>>::rep>
-[[nodiscard]] constexpr bool operator==(const quantity<R1, Rep1>& lhs, const quantity<R2, Rep2>& rhs)
-{
-  using ct = std::common_type_t<quantity<R1, Rep1>, quantity<R2, Rep2>>;
-  const ct ct_lhs(lhs);
-  const ct ct_rhs(rhs);
-  return ct_lhs.numerical_value_ref_in(ct::unit) == ct_rhs.numerical_value_ref_in(ct::unit);
-}
-
-template<auto R1, typename Rep1, auto R2, typename Rep2>
-  requires requires { typename std::common_type_t<quantity<R1, Rep1>, quantity<R2, Rep2>>; } &&
-           std::three_way_comparable<typename std::common_type_t<quantity<R1, Rep1>, quantity<R2, Rep2>>::rep>
-[[nodiscard]] constexpr auto operator<=>(const quantity<R1, Rep1>& lhs, const quantity<R2, Rep2>& rhs)
-{
-  using ct = std::common_type_t<quantity<R1, Rep1>, quantity<R2, Rep2>>;
-  const ct ct_lhs(lhs);
-  const ct ct_rhs(rhs);
-  return ct_lhs.numerical_value_ref_in(ct::unit) <=> ct_rhs.numerical_value_ref_in(ct::unit);
-}
-
 MP_UNITS_EXPORT_END
 
 }  // namespace mp_units

src/core/include/mp-units/framework/quantity_point.h

@@ -413,6 +413,102 @@ public:
     qp.quantity_from_origin_is_an_implementation_detail_ -= q;
     return std::forward<QP>(qp);
   }
+
+  // binary operators on quantity points
+  template<auto R2, typename Rep2>
+  // TODO simplify when gcc catches up
+    requires ReferenceOf<MP_UNITS_REMOVE_CONST(decltype(R2)), PO.quantity_spec>
+  [[nodiscard]] friend constexpr QuantityPoint auto operator+(const quantity_point& qp, const quantity<R2, Rep2>& q)
+    requires requires { qp.quantity_ref_from(PO) + q; }
+  {
+    if constexpr (detail::is_zeroth_point_origin(PO))
+      return ::mp_units::quantity_point{qp.quantity_ref_from(PO) + q};
+    else
+      return ::mp_units::quantity_point{qp.quantity_ref_from(PO) + q, PO};
+  }
+
+  template<auto R1, typename Rep1>
+  // TODO simplify when gcc catches up
+    requires ReferenceOf<MP_UNITS_REMOVE_CONST(decltype(R1)), PO.quantity_spec>
+  [[nodiscard]] friend constexpr QuantityPoint auto operator+(const quantity<R1, Rep1>& q, const quantity_point& qp)
+    requires requires { q + qp.quantity_ref_from(PO); }
+  {
+    return qp + q;
+  }
+
+  template<auto R2, typename Rep2>
+  // TODO simplify when gcc catches up
+    requires ReferenceOf<MP_UNITS_REMOVE_CONST(decltype(R2)), PO.quantity_spec>
+  [[nodiscard]] friend constexpr QuantityPoint auto operator-(const quantity_point& qp, const quantity<R2, Rep2>& q)
+    requires requires { qp.quantity_ref_from(PO) - q; }
+  {
+    if constexpr (detail::is_zeroth_point_origin(PO))
+      return ::mp_units::quantity_point{qp.quantity_ref_from(PO) - q};
+    else
+      return ::mp_units::quantity_point{qp.quantity_ref_from(PO) - q, PO};
+  }
+
+  template<QuantityPointOf<absolute_point_origin> QP2>
+  [[nodiscard]] friend constexpr Quantity auto operator-(const quantity_point& lhs, const QP2& rhs)
+    // TODO consider constraining it for both branches
+    requires requires { lhs.quantity_ref_from(point_origin) - rhs.quantity_ref_from(QP2::point_origin); }
+  {
+    if constexpr (point_origin == QP2::point_origin)
+      return lhs.quantity_ref_from(point_origin) - rhs.quantity_ref_from(QP2::point_origin);
+    else
+      return lhs.quantity_ref_from(point_origin) - rhs.quantity_ref_from(QP2::point_origin) +
+             (lhs.point_origin - rhs.point_origin);
+  }
+
+  template<PointOrigin PO2>
+    requires QuantityPointOf<quantity_point, PO2{}> &&
+             ReferenceOf<std::remove_const_t<decltype(reference)>, PO2::quantity_spec>
+  [[nodiscard]] friend constexpr Quantity auto operator-(const quantity_point& qp, PO2 po)
+  {
+    if constexpr (point_origin == po)
+      return qp.quantity_ref_from(point_origin);
+    else if constexpr (detail::is_derived_from_specialization_of_absolute_point_origin<PO2>) {
+      if constexpr (point_origin == absolute_point_origin)
+        return qp.quantity_ref_from(point_origin);
+      else
+        return qp.quantity_ref_from(point_origin) + (qp.point_origin - qp.absolute_point_origin);
+    } else {
+      if constexpr (point_origin == po.quantity_point.point_origin)
+        return qp.quantity_ref_from(point_origin) - po.quantity_point.quantity_ref_from(po.quantity_point.point_origin);
+      else
+        return qp.quantity_ref_from(point_origin) -
+               po.quantity_point.quantity_ref_from(po.quantity_point.point_origin) +
+               (qp.point_origin - po.quantity_point.point_origin);
+    }
+  }
+
+  template<PointOrigin PO1>
+    requires QuantityPointOf<quantity_point, PO1{}> &&
+             ReferenceOf<std::remove_const_t<decltype(reference)>, PO1::quantity_spec>
+  [[nodiscard]] friend constexpr Quantity auto operator-(PO1 po, const quantity_point& qp)
+  {
+    return -(qp - po);
+  }
+
+  template<QuantityPointOf<absolute_point_origin> QP2>
+    requires std::equality_comparable_with<quantity_type, typename QP2::quantity_type>
+  [[nodiscard]] friend constexpr bool operator==(const quantity_point& lhs, const QP2& rhs)
+  {
+    if constexpr (point_origin == QP2::point_origin)
+      return lhs.quantity_ref_from(point_origin) == rhs.quantity_ref_from(QP2::point_origin);
+    else
+      return lhs - lhs.absolute_point_origin == rhs - rhs.absolute_point_origin;
+  }
+
+  template<QuantityPointOf<absolute_point_origin> QP2>
+    requires std::three_way_comparable_with<quantity_type, typename QP2::quantity_type>
+  [[nodiscard]] friend constexpr auto operator<=>(const quantity_point& lhs, const QP2& rhs)
+  {
+    if constexpr (point_origin == QP2::point_origin)
+      return lhs.quantity_ref_from(point_origin) <=> rhs.quantity_ref_from(QP2::point_origin);
+    else
+      return lhs - lhs.absolute_point_origin <=> rhs - rhs.absolute_point_origin;
+  }
 };
 
 // CTAD
@@ -428,29 +524,7 @@ explicit(is_specialization_of<decltype(quantity_point_like_traits<QP>::to_numeri
   -> quantity_point<quantity_point_like_traits<QP>::reference, quantity_point_like_traits<QP>::point_origin,
                     typename quantity_point_like_traits<QP>::rep>;
 
-template<auto R1, auto PO1, typename Rep1, auto R2, typename Rep2>
+// binary operators on point origins
-// TODO simplify when gcc catches up
-  requires ReferenceOf<MP_UNITS_REMOVE_CONST(decltype(R2)), PO1.quantity_spec>
-[[nodiscard]] constexpr QuantityPoint auto operator+(const quantity_point<R1, PO1, Rep1>& qp,
-                                                     const quantity<R2, Rep2>& q)
-  requires requires { qp.quantity_ref_from(PO1) + q; }
-{
-  if constexpr (detail::is_zeroth_point_origin(PO1))
-    return quantity_point{qp.quantity_ref_from(PO1) + q};
-  else
-    return quantity_point{qp.quantity_ref_from(PO1) + q, PO1};
-}
-
-template<auto R1, typename Rep1, auto R2, auto PO2, typename Rep2>
-// TODO simplify when gcc catches up
-  requires ReferenceOf<MP_UNITS_REMOVE_CONST(decltype(R1)), PO2.quantity_spec>
-[[nodiscard]] constexpr QuantityPoint auto operator+(const quantity<R1, Rep1>& q,
-                                                     const quantity_point<R2, PO2, Rep2>& qp)
-  requires requires { q + qp.quantity_ref_from(PO2); }
-{
-  return qp + q;
-}
-
 template<PointOrigin PO, Quantity Q>
   requires ReferenceOf<std::remove_const_t<decltype(Q::reference)>, PO::quantity_spec>
 [[nodiscard]] constexpr quantity_point<Q::reference, PO{}, typename Q::rep> operator+(PO, Q&& q)
@@ -465,19 +539,6 @@ template<Quantity Q, PointOrigin PO>
   return po + std::forward<Q>(q);
 }
 
-template<auto R1, auto PO1, typename Rep1, auto R2, typename Rep2>
-// TODO simplify when gcc catches up
-  requires ReferenceOf<MP_UNITS_REMOVE_CONST(decltype(R2)), PO1.quantity_spec>
-[[nodiscard]] constexpr QuantityPoint auto operator-(const quantity_point<R1, PO1, Rep1>& qp,
-                                                     const quantity<R2, Rep2>& q)
-  requires requires { qp.quantity_ref_from(PO1) - q; }
-{
-  if constexpr (detail::is_zeroth_point_origin(PO1))
-    return quantity_point{qp.quantity_ref_from(PO1) - q};
-  else
-    return quantity_point{qp.quantity_ref_from(PO1) - q, PO1};
-}
-
 template<PointOrigin PO, Quantity Q>
   requires ReferenceOf<std::remove_const_t<decltype(Q::reference)>, PO::quantity_spec>
 [[nodiscard]] constexpr QuantityPoint auto operator-(PO po, const Q& q)
@@ -486,47 +547,6 @@ template<PointOrigin PO, Quantity Q>
   return po + (-q);
 }
 
-template<QuantityPoint QP1, QuantityPointOf<QP1::absolute_point_origin> QP2>
-[[nodiscard]] constexpr Quantity auto operator-(const QP1& lhs, const QP2& rhs)
-  // TODO consider constraining it for both branches
-  requires requires { lhs.quantity_ref_from(QP1::point_origin) - rhs.quantity_ref_from(QP2::point_origin); }
-{
-  if constexpr (QP1::point_origin == QP2::point_origin)
-    return lhs.quantity_ref_from(QP1::point_origin) - rhs.quantity_ref_from(QP2::point_origin);
-  else
-    return lhs.quantity_ref_from(QP1::point_origin) - rhs.quantity_ref_from(QP2::point_origin) +
-           (lhs.point_origin - rhs.point_origin);
-}
-
-template<PointOrigin PO, QuantityPointOf<PO{}> QP>
-  requires ReferenceOf<std::remove_const_t<decltype(QP::reference)>, PO::quantity_spec>
-[[nodiscard]] constexpr Quantity auto operator-(const QP& qp, PO po)
-{
-  if constexpr (QP::point_origin == po)
-    return qp.quantity_ref_from(QP::point_origin);
-  else if constexpr (detail::is_derived_from_specialization_of_absolute_point_origin<PO>) {
-    if constexpr (QP::point_origin == QP::absolute_point_origin)
-      return qp.quantity_ref_from(QP::point_origin);
-    else
-      return qp.quantity_ref_from(QP::point_origin) + (qp.point_origin - qp.absolute_point_origin);
-  } else {
-    if constexpr (QP::point_origin == po.quantity_point.point_origin)
-      return qp.quantity_ref_from(QP::point_origin) -
-             po.quantity_point.quantity_ref_from(po.quantity_point.point_origin);
-    else
-      return qp.quantity_ref_from(QP::point_origin) -
-             po.quantity_point.quantity_ref_from(po.quantity_point.point_origin) +
-             (qp.point_origin - po.quantity_point.point_origin);
-  }
-}
-
-template<PointOrigin PO, QuantityPointOf<PO{}> QP>
-  requires ReferenceOf<std::remove_const_t<decltype(QP::reference)>, PO::quantity_spec>
-[[nodiscard]] constexpr Quantity auto operator-(PO po, const QP& qp)
-{
-  return -(qp - po);
-}
-
 template<PointOrigin PO1, detail::SameAbsolutePointOriginAs<PO1{}> PO2>
   requires QuantitySpecOf<std::remove_const_t<decltype(PO1::quantity_spec)>, PO2::quantity_spec> &&
            (detail::is_derived_from_specialization_of_relative_point_origin<PO1> ||
@@ -542,26 +562,6 @@ template<PointOrigin PO1, detail::SameAbsolutePointOriginAs<PO1{}> PO2>
   }
 }
 
-template<QuantityPoint QP1, QuantityPointOf<QP1::absolute_point_origin> QP2>
-  requires std::three_way_comparable_with<typename QP1::quantity_type, typename QP2::quantity_type>
-[[nodiscard]] constexpr auto operator<=>(const QP1& lhs, const QP2& rhs)
-{
-  if constexpr (QP1::point_origin == QP2::point_origin)
-    return lhs.quantity_ref_from(QP1::point_origin) <=> rhs.quantity_ref_from(QP2::point_origin);
-  else
-    return lhs - lhs.absolute_point_origin <=> rhs - rhs.absolute_point_origin;
-}
-
-template<QuantityPoint QP1, QuantityPointOf<QP1::absolute_point_origin> QP2>
-  requires std::equality_comparable_with<typename QP1::quantity_type, typename QP2::quantity_type>
-[[nodiscard]] constexpr bool operator==(const QP1& lhs, const QP2& rhs)
-{
-  if constexpr (QP1::point_origin == QP2::point_origin)
-    return lhs.quantity_ref_from(QP1::point_origin) == rhs.quantity_ref_from(QP2::point_origin);
-  else
-    return lhs - lhs.absolute_point_origin == rhs - rhs.absolute_point_origin;
-}
-
 MP_UNITS_EXPORT_END
 
 }  // namespace mp_units