Less intrusive

src/core/matpack/matpack_mdspan_cdata_t.h

@@ -10,8 +10,6 @@
 namespace matpack {
 template <typename T, Size... dims>
 struct [[nodiscard]] cdata_t {
-  constexpr static bool matpack_magic_cdata = true;
-
   constexpr static Size N     = sizeof...(dims);
   constexpr static Size ndata = (dims * ...);
 
@@ -346,10 +344,10 @@ struct tuple_element<I, T> {
 };
 }  // namespace std
 
-using Vector2 = matpack::cdata_t<Numeric, 2>;
-using Vector3 = matpack::cdata_t<Numeric, 3>;
-using Vector4 = matpack::cdata_t<Numeric, 4>;
-using Vector7 = matpack::cdata_t<Numeric, 7>;
-using Matrix33 = matpack::cdata_t<Numeric, 3, 3>;
-using Matrix44 = matpack::cdata_t<Numeric, 4, 4>;
+using Vector2         = matpack::cdata_t<Numeric, 2>;
+using Vector3         = matpack::cdata_t<Numeric, 3>;
+using Vector4         = matpack::cdata_t<Numeric, 4>;
+using Vector7         = matpack::cdata_t<Numeric, 7>;
+using Matrix33        = matpack::cdata_t<Numeric, 3, 3>;
+using Matrix44        = matpack::cdata_t<Numeric, 4, 4>;
 using ComplexMatrix44 = matpack::cdata_t<Complex, 4, 4>;

src/core/matpack/matpack_mdspan_common_types.h

@@ -105,7 +105,13 @@ template <class T>
 concept any_strided_view = any_strided_view_t<std::remove_cvref_t<T>>::value;
 
 template <class T>
-concept any_cdata = std::remove_cvref_t<T>::matpack_magic_cdata;
+struct any_cdata_t : std::false_type {};
+
+template <class T, Size... dims>
+struct any_cdata_t<cdata_t<T, dims...>> : std::true_type {};
+
+template <class T>
+concept any_cdata = any_cdata_t<std::remove_cvref_t<T>>::value;
 
 template <class T>
 struct any_grid_t : std::false_type {};

src/core/rtepack/rtepack_common.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <matpack.h>
+
+namespace rtepack {
+struct propmat;
+struct muelmat;
+struct specmat;
+struct stokvec;
+}  // namespace rtepack
+
+namespace matpack {
+template <>
+struct any_cdata_t<rtepack::propmat> : std::true_type {};
+template <>
+struct any_cdata_t<rtepack::muelmat> : std::true_type {};
+template <>
+struct any_cdata_t<rtepack::specmat> : std::true_type {};
+template <>
+struct any_cdata_t<rtepack::stokvec> : std::true_type {};
+}  // namespace matpack

src/core/rtepack/rtepack_mueller_matrix.h

@@ -4,6 +4,8 @@
 #include <matpack.h>
 #include <xml.h>
 
+#include "rtepack_common.h"
+
 namespace rtepack {
 
 //! A 4x4 matrix of Numeric values to be used as a Mueller Matrix

src/core/rtepack/rtepack_propagation_matrix.h

@@ -6,6 +6,8 @@
 
 #include <numeric>
 
+#include "rtepack_common.h"
+
 namespace rtepack {
 struct propmat final : Vector7 {
   constexpr propmat(Numeric a = 0.0,

src/core/rtepack/rtepack_spectral_matrix.h

@@ -4,6 +4,8 @@
 #include <matpack.h>
 #include <xml.h>
 
+#include "rtepack_common.h"
+
 namespace rtepack {
 
 //! A 4x4 matrix of Complex values to be used as a Mueller Matrix

src/core/rtepack/rtepack_stokes_vector.h

@@ -7,6 +7,8 @@
 
 #include <utility>
 
+#include "rtepack_common.h"
+
 namespace rtepack {
 struct stokvec final : Vector4 {
   [[nodiscard]] constexpr stokvec(Numeric i = 0.0,