feat: derived_XXX are not constrained with SymbolicConstant

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

@@ -52,7 +52,7 @@ import std;
 
 namespace mp_units {
 
-template<typename... Expr>
+template<detail::SymbolicConstant... Expr>
 struct derived_dimension;
 
 MP_UNITS_EXPORT struct dimension_one;
@@ -165,7 +165,7 @@ struct base_dimension : detail::dimension_interface {
  * @note User should not instantiate this type! It is not exported from the C++ module. The library will
  *       instantiate this type automatically based on the dimensional arithmetic equation provided by the user.
  */
-template<typename... Expr>
+template<detail::SymbolicConstant... Expr>
 struct derived_dimension final : detail::dimension_interface, detail::derived_dimension_impl<Expr...> {};
 
 /**

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

@@ -491,7 +491,7 @@ struct derived_quantity_spec_impl :
  * @note User should not instantiate this type! It is not exported from the C++ module. The library will
  *       instantiate this type automatically based on the dimensional arithmetic equation provided by the user.
  */
-template<typename... Expr>
+template<detail::SymbolicConstant... Expr>
 struct derived_quantity_spec final : detail::derived_quantity_spec_impl<Expr...> {};
 
 /**

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

@@ -78,7 +78,7 @@ concept NamedQuantitySpec =
 
 }  // namespace detail
 
-template<typename... Expr>
+template<detail::SymbolicConstant... Expr>
 struct derived_quantity_spec;
 
 namespace detail {

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

@@ -146,7 +146,7 @@ template<Unit From, Unit To>
     return false;
 }
 
-template<typename... Expr>
+template<detail::SymbolicConstant... Expr>
 struct derived_unit;
 
 namespace detail {
@@ -513,7 +513,7 @@ struct derived_unit_impl : detail::unit_interface, detail::expr_fractions<one, E
  * @note User should not instantiate this type! It is not exported from the C++ module. The library will
  *       instantiate this type automatically based on the unit arithmetic equation provided by the user.
  */
-template<typename... Expr>
+template<detail::SymbolicConstant... Expr>
 struct derived_unit final : detail::derived_unit_impl<Expr...> {};
 
 /**