SWIGUpcast problem / assigning to .. from incompatible type

Hi,

I've been posting a few post about this problem already so sorry about the noise.

But I think I've tracked the root cause.

Background: I'm trying to upgrade existing occjava from OCE to OCC 7.3.0.

The main problem I'm experiencing stems from the fact that OCC 7.0.0
gave gave up a hierarchy of classes Handle_XXX and replaced that with
opencascade::handle<XXX> (hidden behind macro DEFINE_STANDARD_HANDLE).

In the OCC context Handle is basically a pointer to a pointer to the
actual instance of a class and originally the Handle_XXXX hierarchy
mirrored the actual class hierarchy.

And this made the upcasting work with the occjava SWIG defs.

But now it fails cause every Handle_XXX (aka opencascade::handle<XXX>)
is a distinct type.

So I'm looking for ideas how to fix this. Preferably with a typemap
or few cause there are a lot of classes and handles in OCC (over
8000 files in /usr/local/include/opencascade).

I've made a minimal (if not totally self contained experiment project
to illustrate the problem).

You can download a zip file of the experiment here:

http://eazycnc.com/temp/experiments.zip

and I will also collect the gist of it below.

wbr Kusti


/// Standard_Handle.hxx (FRAGMENT) ---------------------------
template <class T>
  class handle
  {
  public:
    //! STL-compliant typedef of contained type
    typedef T element_type;
    ...
   handle () : entity(0) {}

    //! Constructor from pointer to new object
    handle (const T *thePtr) : entity(const_cast<T*>(thePtr))
    {
      ...
    }
 ...
  private:
    Standard_Transient* entity;
  };
...
#define DEFINE_STANDARD_HANDLECLASS(C1,C2,BC) class C1; typedef Handle(C1) Handle_##C1;
#define DEFINE_STANDARD_HANDLE(C1,C2) DEFINE_STANDARD_HANDLECLASS(C1,C2,Standard_Transient)
#define DEFINE_STANDARD_PHANDLE(C1,C2) DEFINE_STANDARD_HANDLECLASS(C1,C2,Standard_Persistent)


/// experiment.hxx --------------------------------------------
#include "/usr/local/include/opencascade/Standard_Handle.hxx"

DEFINE_STANDARD_HANDLE(Geom_Geometry,Standard_Transient);
DEFINE_STANDARD_HANDLE(Geom_Curve,Standard_Transient);


/// experiment.cxx --------------------------------------------
#include "experiment.hxx"


/// experiment.i ----------------------------------------------
%module experiment
%{
#include "experiment.hxx"
%}

%include "experiment.hxx"

%rename(Geom_Curve) Handle_Geom_Curve;
%rename(Geom_Geometry) Handle_Geom_Geometry;

class Handle_Geom_Geometry
{
	Handle_Geom_Geometry()=0;
};

class Handle_Geom_Curve : public Handle_Geom_Geometry
{
	Handle_Geom_Curve()=0;
};


/// Makefile ---------------------------------------------------
all:
	c++ -std=c++11 -c -I/usr/local/include/opencascade -o experiment.so experiment.cxx
	swig -c++ -java experiment.i
	c++ -std=c++11 -c -I/usr/local/include/opencascade -I/Library/Java/JavaVirtualMachines/jdk-11.0.6.jdk/Contents/Home/include -I/Library/Java/JavaVirtualMachines/jdk-11.0.6.jdk/Contents/Home/include/darwin -o experiment_wrap.so experiment_wrap.cxx


/// experiment_wrap.cxx (FRAGMENT) -----------------------------

SWIGEXPORT jlong JNICALL Java_experimentJNI_Geom_1Curve_1SWIGUpcast(JNIEnv *jenv, jclass jcls, jlong jarg1) {
    jlong baseptr = 0;
    (void)jenv;
    (void)jcls;
    *(Handle_Geom_Geometry **)&baseptr = *(Handle_Geom_Curve **)&jarg1;
    return baseptr;
}


which fails to compile like this



// Error ========================================================

experiment_wrap.cxx:266:42: error: assigning to 'Handle_Geom_Geometry *' (aka 'handle<Geom_Geometry> *') from incompatible type 'Handle_Geom_Curve *' (aka 'handle<Geom_Curve> *')
    *(Handle_Geom_Geometry **)&baseptr = *(Handle_Geom_Curve **)&jarg1;