C++ base class needs at least one virtual method

[ezneh]

Hello

While trying to make a 1:1 binding to a C/C++ lib, I got the 
following issue:

I only have access to the .h header file, and in there I have 
this:

class someclass {};
class otherclass : public someclass {};

When trying to translate that header file to D, I ended with the 
following code:

extern(C++):
class someclass {}
class otherclass : someclass {}

But when compiling, the following error comes up:

Error: class `modulename.otherclass` C++ base class someclass 
needs at least one virtual function


Am I missing something or is there a bug somewhere ?
I don't have access to the .cpp file and cannot see what are the 
methods of someclass / otherclass are.

Any suggestion ?