disable using constructors for SWIG

needs SWIG 4.2

src/include/stir/RegisteredParsingObject.h

@@ -77,7 +77,11 @@ template <typename Derived, typename Base, typename Parent = Base>
 class RegisteredParsingObject : public Parent
 {
 public:
+#ifndef SWIG
+  // import constructors from Parent
+  // Note: currently disabled for SWIG as that needs SWIG 4.2
   using Parent::Parent;
+#endif
 
   //! Construct a new object (of type Derived) by parsing the istream
   /*! When the istream * is 0, questions are asked interactively.
@@ -95,6 +99,7 @@ class RegisteredParsingObject : public Parent
   inline std::string parameter_info() override;
 
 public:
+#ifndef SWIG
   //! A helper class to allow automatic registration.
   struct RegisterIt
   {
@@ -113,18 +118,19 @@ class RegisteredParsingObject : public Parent
     */
     ~RegisterIt()
     {
-#if 0
+#  if 0
       // does not work yet, as registry might be destructed before this
       // RegisterIt object. A solution to this problem is coming up.
       cerr << "In RegisterIt destructor for " << Derived::registered_name<<endl;
       cerr <<"Current keys: ";
       Parent::registry().list_keys(cerr);
       Parent::registry().remove_from_registry(Derived::registered_name);
-#endif
+#  endif
     }
   };
   // RegisterIt needs to be a friend to have access to registry()
   friend struct RegisterIt;
+#endif
 };
 
 END_NAMESPACE_STIR

src/include/stir/recon_buildblock/CUDA/CudaRelativeDifferencePrior.h

@@ -26,8 +26,11 @@ class CudaRelativeDifferencePrior : public RegisteredParsingObject<CudaRelativeD
 public:
   // Name which will be used when parsing a GeneralisedPrior object
   inline static const char* const registered_name = "Cuda Relative Difference Prior";
-  // Constructors
+#ifndef SWIG
+  // import constructors from base_type
+  // Note: currently disabled for SWIG as that needs SWIG 4.2
   using base_type::base_type;
+#endif
 
   // Overridden methods
   double compute_value(const DiscretisedDensity<3, elemT>& current_image_estimate) override;