fix upcasting problem (#77 thanks to cantora)

llvmpy/gen/binding.py

@@ -333,7 +333,7 @@ class Class(SubModule, _Type):
         writer.die_if_false(raw, verbose=name)
         ptrty = ptr(self).fullname
         ty = self.fullname
-        fmt = 'typecast< %(ty)s >::from(%(raw)s)'
+        fmt = 'unwrap_as<%(ty)s, %(name)s >::from(%(raw)s)'
         casted = writer.declare(ptrty, fmt % locals())
         writer.die_if_false(casted)
         return casted

llvmpy/gen/codegen.py

@@ -202,7 +202,8 @@ class CppCodeWriter(CodeWriterBase):
 
     def pycapsule_new(self, ptr, name, clsname):
         name_soften = mangle(name)
-        ret = self.call('pycapsule_new', 'PyObject*', ptr, quote(name),
+        cast_to_base = 'cast_to_base<%s >::from(%s)' % (name, ptr)
+        ret = self.call('pycapsule_new', 'PyObject*', cast_to_base, quote(name),
                         quote(clsname))
         with self.block('if (!%(ret)s)' % locals()):
             self.return_null()

llvmpy/include/llvm_binding/conversion.h

@@ -254,10 +254,11 @@ PyObject* py_float_from(const double& val) {
 // casting
 template<class Td>
 struct typecast {
-    template<class Ts> static
-    Td* from(Ts* src) {
-        return llvm::dyn_cast<Td>(src);
-    }
+// Unused
+//    template<class Ts> static
+//    Td* from(Ts* src) {
+//        return llvm::dyn_cast<Td>(src);
+//    }
 
     static
     Td* from(void* src) {
@@ -265,3 +266,24 @@ struct typecast {
     }
 };
 
+template<class Td, class Tbase>
+struct unwrap_as {
+    static
+    Td* from(void* src) {
+        Tbase* base = static_cast<Tbase*>(src);
+        return static_cast<Td*>(base);
+    }
+};
+
+template<class Td>
+struct cast_to_base {
+    template<class Ts> static
+    Td* from(Ts* src){
+        return static_cast<Td*>(src);
+    }
+    
+    template<class Ts> static
+    const Td* from(const Ts* src){
+        return static_cast<const Td*>(src);
+    }
+};