From d6fba478b91f9a084d281c6bbd53caa9e555edec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johel=20Ernesto=20Guerrero=20Pe=C3=B1a?=
 <johelegp@gmail.com>
Date: Tue, 8 Sep 2020 20:50:11 -0400
Subject: [PATCH] feat: working dimension concepts with UNITS_DOWNCAST OFF

continuation of https://github.com/johelegp/units-1/commit/22e6107d0f363d894dcef98dd427e4004ac88f30
---
 src/include/units/physical/dimensions.h | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/include/units/physical/dimensions.h b/src/include/units/physical/dimensions.h
index f23859f5..2b3b1ffa 100644
--- a/src/include/units/physical/dimensions.h
+++ b/src/include/units/physical/dimensions.h
@@ -24,16 +24,25 @@
 
 #include <units/base_dimension.h>
 #include <units/bits/external/type_traits.h>
+#include <units/derived_dimension.h>
 #include <units/quantity.h>
 #include <units/unit.h>
 
 namespace units::physical {
 
+namespace detail {
+
+template<template<typename...> typename DimTemplate, typename Child, Unit U, Exponent... Es>
+  requires requires { typename DimTemplate<Child, U, typename Es::dimension...>; }
+void to_base_derived_dimension_of(const volatile derived_dimension<Child, U, Es...>*);
+
+} // namespace detail
+
 template<typename Dim, template<typename...> typename DimTemplate>
-concept DimensionOf = Dimension<Dim> && is_derived_from_specialization_of<Dim, DimTemplate>;
+concept DimensionOf = Dimension<Dim> && (is_derived_from_specialization_of<Dim, DimTemplate> || requires(const volatile Dim* x) { detail::to_base_derived_dimension_of<DimTemplate>(x); });
 
 template<typename Q, template<typename...> typename DimTemplate>
-concept QuantityOf = Quantity<Q> && is_derived_from_specialization_of<typename Q::dimension, DimTemplate>;
+concept QuantityOf = Quantity<Q> && DimensionOf<typename Q::dimension, DimTemplate>;
 
 // ------------------------ base dimensions -----------------------------