Do I need to rebuild libg++ to go with my new g++?
==================================================

   "After I upgraded g++ to the latest version, I'm seeing undefined
symbols."

   or

   "If I upgrade to a new version of g++, do I need to reinstall
libg++?"

   As a rule, the first two digits of your g++ and libg++ should be the
same.  Normally when you do an upgrade in the "minor version number"
(2.5.7 to 2.5.8, say) there isn't a need to rebuild libg++, but there
have been a couple of exceptions in the past.