refactor: concept cleanup

src/core/include/mp-units/bits/dimension_concepts.h

@@ -34,7 +34,11 @@ struct base_dimension;
 namespace detail {
 
 template<basic_symbol_text Symbol>
-void to_base_base_dimension(const volatile base_dimension<Symbol>*);
+void to_base_specialization_of_base_dimension(const volatile base_dimension<Symbol>*);
+
+template<typename T>
+inline constexpr bool is_derived_from_specialization_of_base_dimension =
+  requires(T* t) { to_base_specialization_of_base_dimension(t); };
 
 template<typename T>
 inline constexpr bool is_specialization_of_base_dimension = false;
@@ -48,7 +52,8 @@ inline constexpr bool is_specialization_of_base_dimension<base_dimension<Symbol>
  * Satisfied by all dimension types derived from a specialization of `base_dimension`.
  */
 template<typename T>
-concept BaseDimension = requires(T* t) { to_base_base_dimension(t); } && (!is_specialization_of_base_dimension<T>);
+concept BaseDimension =
+  is_derived_from_specialization_of_base_dimension<T> && (!is_specialization_of_base_dimension<T>);
 
 template<typename T>
 struct is_dimension_one : std::false_type {};

src/core/include/mp-units/bits/quantity_concepts.h

@@ -37,6 +37,10 @@ namespace detail {
 template<auto R, typename Rep>
 void to_base_specialization_of_quantity(const volatile quantity<R, Rep>*);
 
+template<typename T>
+inline constexpr bool is_derived_from_specialization_of_quantity =
+  requires(T* t) { to_base_specialization_of_quantity(t); };
+
 }  // namespace detail
 
 /**
@@ -45,7 +49,7 @@ void to_base_specialization_of_quantity(const volatile quantity<R, Rep>*);
  * Satisfied by all types being a either specialization or derived from `quantity`
  */
 template<typename T>
-concept Quantity = requires(T* t) { detail::to_base_specialization_of_quantity(t); };
+concept Quantity = detail::is_derived_from_specialization_of_quantity<T>;
 
 /**
  * @brief A concept matching all quantities with provided dimension or quantity spec

src/core/include/mp-units/bits/quantity_point_concepts.h

@@ -81,7 +81,11 @@ template<auto R, auto PO, typename Rep>
 void to_base_specialization_of_quantity_point(const volatile quantity_point<R, PO, Rep>*);
 
 template<typename T>
-  requires requires(T* t) { detail::to_base_specialization_of_quantity_point(t); }
+inline constexpr bool is_derived_from_specialization_of_quantity_point =
+  requires(T* t) { to_base_specialization_of_quantity_point(t); };
+
+template<typename T>
+  requires is_derived_from_specialization_of_quantity_point<T>
 inline constexpr bool is_quantity_point<T> = true;
 
 }  // namespace detail

src/core/include/mp-units/bits/quantity_spec_concepts.h

@@ -56,6 +56,10 @@ template<typename T, auto... Args>
 void to_base_specialization_of_quantity_spec(const volatile quantity_spec<T, Args...>*);
 #endif
 
+template<typename T>
+inline constexpr bool is_derived_from_specialization_of_quantity_spec =
+  requires(T* t) { to_base_specialization_of_quantity_spec(t); };
+
 #ifdef __cpp_explicit_this_parameter
 template<BaseDimension auto Dim, auto... Args>
 template<auto... Args>
@@ -65,6 +69,10 @@ template<typename Self, BaseDimension auto Dim, auto... Args>
 void to_base_specialization_of_base_quantity_spec(const volatile quantity_spec<Self, Dim, Args...>*);
 #endif
 
+template<typename T>
+inline constexpr bool is_derived_from_specialization_of_base_quantity_spec =
+  requires(T* t) { to_base_specialization_of_base_quantity_spec(t); };
+
 template<typename T>
 inline constexpr bool is_specialization_of_quantity_spec = false;
 
@@ -82,7 +90,7 @@ inline constexpr bool is_specialization_of_quantity_spec<quantity_spec<T, Args..
  * Satisfied by all types that derive from `quantity_spec`.
  */
 template<typename T>
-concept NamedQuantitySpec = requires(T* t) { to_base_specialization_of_quantity_spec(t); } &&
+concept NamedQuantitySpec = is_derived_from_specialization_of_quantity_spec<T> &&
                             (!is_specialization_of_quantity_spec<T>)&&(!QuantityKindSpec<T>);
 
 /**
@@ -92,7 +100,7 @@ concept NamedQuantitySpec = requires(T* t) { to_base_specialization_of_quantity_
  * as a template parameter.
  */
 template<typename T>
-concept BaseQuantitySpec = NamedQuantitySpec<T> && requires(T* t) { to_base_specialization_of_base_quantity_spec(t); };
+concept BaseQuantitySpec = NamedQuantitySpec<T> && is_derived_from_specialization_of_base_quantity_spec<T>;
 
 template<typename T>
 struct is_dimensionless : std::false_type {};

src/core/include/mp-units/bits/unit_concepts.h

@@ -68,10 +68,11 @@ inline constexpr bool is_specialization_of_named_unit<named_unit<Symbol, Args...
 /**
  * @brief A concept matching all units with special names
  *
- * Satisfied by all unit types derived from the specialization of `named_unit` (but not constant units).
+ * Satisfied by all unit types derived from the specialization of `named_unit`.
  */
 template<typename T>
-concept NamedUnit = Unit<T> && detail::is_derived_from_specialization_of_named_unit<T>;
+concept NamedUnit =
+  Unit<T> && detail::is_derived_from_specialization_of_named_unit<T> && (!detail::is_specialization_of_named_unit<T>);
 
 }  // namespace detail