cast in gdb python results in virtual baseclass botch

[Christoph Mathys]

I try to cast a gdb.Value to another type. There are cases where it
works, and others where it doesn't, and I don't really know why. If it
doesn't work, I get the following exception when I call cast():
RuntimeError: virtual baseclass botch

I use gdb 7.2, which apparently does not yet support dynamic_cast().

Both variables are stored inside a boost::shared_ptr, and I try to
cast to contained interface pointer to a specific implementation
pointer.

Christoph