Here's the patch I've been using for this. It'd be better to rework
the way those functions use those obstacks, but...
2006-12-05 Jim Blandy <jimb@codesourcery.com>
* cp-valprint.c (cp_print_value_fields, cp_print_value):
Initialize tmp_obstack, to avoid warnings.
* p-valprint.c (pascal_object_print_value_fields)
(pascal_object_print_value): Same.
This is silly, at least if they are really unecessary. It's a bug in GCC
and should be fixed. I mean, GCC should get better at detecting this sort
of things; not give more false positives.
Markus, can you file a GCC bug report for this?