The bug is detailed here: 
http://sourceware.org/bugzilla/show_bug.cgi?id=10008

In summary, given this class:

class Y : public std::tr1::unordered_map<int, char *>
{
public:
  Y()
  {
  }
};

Any Python pretty-printers that have been written and registered to 
print std::tr1::unordered_map will not work on Y. But there is no 
reason, given the lack of a more specialized printer for Y, why the 
printer for unordered_map should not print the parts of Y it can 
accurately print. This patch attempts to find a base class printer if a 
specialized printer does not exist for the class in question.

Built and tested on x8664, with no regressions.

Phil

2009-03-27  Phil Muldoon  <pmuldoon@redhat.com>

       * cp-valprint.c (cp_print_value_fields): Attempt to run
       apply_val_pretty_print on the baseclass of a class.