t cctbx::boost_python::&lt;unnamed&gt;::add_pair*
   ') to type `void*' (source type is not polymorphic)</pre>

    We do not know a general workaround, but if the definition of
    <tt>your_type</tt> can be modified the following was found
    to work in all cases encountered so far:<pre>struct your_type
{
  // before defining any member data
#if defined(__MACH__) &amp;&amp; defined(__APPLE_CC__) &amp;&amp; __APPLE_CC__ == 1493
  bool dummy_;
#endif
  // now your member data, e.g.
  double x;
  int j;
  //