refactor: unnecessary custom versions of is_specialization_of removed

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

@@ -56,12 +56,6 @@ struct per {};
 
 namespace detail {
 
-template<typename T>
-constexpr bool is_specialization_of_per = false;
-
-template<typename... Ts>
-constexpr bool is_specialization_of_per<per<Ts...>> = true;
-
 template<int Num, int... Den>
 constexpr bool valid_ratio = true;
 
@@ -312,7 +306,7 @@ template<template<typename> typename OneType, typename List>
   else {
     using last_element = type_list_back<List>;
 
-    if constexpr (is_specialization_of_per<last_element>) {
+    if constexpr (is_specialization_of<last_element, per>) {
       if constexpr (size == 2 && OneType<type_list_front<List>>::value)
         return expr_fractions_result<type_list<>, type_list_map<last_element, type_list>>{};
       else {

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

@@ -53,13 +53,7 @@ struct kind_of_;
 namespace detail {
 
 template<typename T>
-constexpr bool is_specialization_of_kind_of = false;
+concept QuantityKindSpec = is_specialization_of<T, kind_of_>;
-
-template<typename Q>
-constexpr bool is_specialization_of_kind_of<kind_of_<Q>> = true;
-
-template<typename T>
-concept QuantityKindSpec = is_specialization_of_kind_of<T>;
 
 #if MP_UNITS_API_NO_CRTP
 template<auto... Args>

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

@@ -32,17 +32,6 @@ namespace mp_units {
 MP_UNITS_EXPORT template<QuantitySpec Q, Unit U>
 struct reference;
 
-namespace detail {
-
-// do not refactor below to a variable template - GCC-11 does not like it
-template<typename T>
-struct is_specialization_of_reference : std::false_type {};
-
-template<typename Q, typename U>
-struct is_specialization_of_reference<reference<Q, U>> : std::true_type {};
-
-}  // namespace detail
-
 MP_UNITS_EXPORT_BEGIN
 
 [[nodiscard]] consteval QuantitySpec auto get_quantity_spec(AssociatedUnit auto u);
@@ -67,7 +56,7 @@ template<typename Q, typename U>
  * Satisfied by all specializations of @c reference.
  */
 template<typename T>
-concept Reference = AssociatedUnit<T> || detail::is_specialization_of_reference<T>::value;
+concept Reference = AssociatedUnit<T> || is_specialization_of<T, reference>;
 
 /**
  * @brief A concept matching all references with provided quantity spec

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

@@ -533,12 +533,6 @@ template<Unit T, typename... Expr>
   return canonical_unit{num.mag / den.mag, num.reference_unit / den.reference_unit};
 }
 
-template<typename T>
-constexpr bool is_specialization_of_derived_unit = false;
-
-template<typename... Expr>
-constexpr bool is_specialization_of_derived_unit<derived_unit<Expr...>> = true;
-
 }  // namespace detail
 
 MP_UNITS_EXPORT_BEGIN
@@ -564,7 +558,7 @@ template<std::intmax_t Num, std::intmax_t Den = 1, Unit U>
     return u;
   else if constexpr (detail::is_specialization_of_scaled_unit<U>)
     return scaled_unit<pow<Num, Den>(U::mag), decltype(pow<Num, Den>(U::reference_unit))>{};
-  else if constexpr (detail::is_specialization_of_derived_unit<U>)
+  else if constexpr (is_specialization_of<U, derived_unit>)
     return detail::expr_pow<Num, Den, derived_unit, struct one, detail::type_list_of_unit_less>(u);
   else if constexpr (Den == 1)
     return derived_unit<power<U, Num>>{};