From 2ddbb365f38bebe6edb83f4d771f98a4469e41b5 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Tue, 1 Aug 2023 11:59:08 +0200
Subject: [PATCH] feat: `QuantityPointOf` concept now has a special case for
 `absolute_point_origin`

---
 .../include/mp-units/bits/quantity_point_concepts.h  | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/core/include/mp-units/bits/quantity_point_concepts.h b/src/core/include/mp-units/bits/quantity_point_concepts.h
index 184864c9..a27af90b 100644
--- a/src/core/include/mp-units/bits/quantity_point_concepts.h
+++ b/src/core/include/mp-units/bits/quantity_point_concepts.h
@@ -37,6 +37,12 @@ namespace detail {
 template<typename T>
 inline constexpr bool is_quantity_point = false;
 
+template<typename T>
+inline constexpr bool is_specialization_of_absolute_point_origin = false;
+
+template<auto Q>
+inline constexpr bool is_specialization_of_absolute_point_origin<absolute_point_origin<Q>> = true;
+
 template<auto Q>
 void to_base_specialization_of_absolute_point_origin(const volatile absolute_point_origin<Q>*);
 
@@ -102,7 +108,11 @@ concept QuantityPointOf =
   QuantityPoint<QP> &&
   (ReferenceOf<std::remove_const_t<decltype(QP::reference)>, V> ||
    (PointOrigin<std::remove_const_t<decltype(V)>> &&
-    std::convertible_to<std::remove_const_t<decltype(QP::absolute_point_origin)>, std::remove_const_t<decltype(V)>>));
+    (std::same_as<std::remove_const_t<decltype(QP::absolute_point_origin)>, std::remove_const_t<decltype(V)>> ||
+     (detail::is_specialization_of_absolute_point_origin<std::remove_const_t<decltype(QP::absolute_point_origin)>> &&
+      detail::is_specialization_of_absolute_point_origin<std::remove_const_t<decltype(V)>> &&
+      implicitly_convertible(QP::absolute_point_origin.quantity_spec, V.quantity_spec) &&
+      !detail::DerivedFromQuantityKindSpecOf<QP::absolute_point_origin.quantity_spec, V.quantity_spec>))));
 
 /**
  * @brief A concept matching all external quantity point like types