Example source code from the following page http://libxmlplusplus.sourceforge.net/docs/manual/html/ar01s02.html won't compile with libxmlpp-2.20.0 in Gentoo. Apparently the header libxml++config.h is not installed during the emerge operation. Emerging the previous version, libxmlpp-2.13.1, works ok.
Apparently the problem has been reported elsewhere too: http://www.nabble.com/libxml++config.h-missing---what-package-should-provide-the-file--t4689114.html
# qfile libxml++config.h dev-cpp/libxmlpp (/usr/lib/libxml++-2.6/include/libxml++config.h) # pkg-config --cflags libxml++-2.6 -I/usr/include/libxml++-2.6 ....... No wonder you're not getting that file. Now as to why it's installed there instead of /usr/include/libxml++-2.6 is for you/upstream to find out :) (I'll eventually get to look at this, but the more you dig on your own, the easier it's going to be to fix this) Thanks for the bug report
In case I wasn't clear, please file a bug upstream with the info here and add gnome-mm@gentoo.org as a CC on it. Thanks :)
Rémi: you are right, sorry for not checking more carefully. Reported to GNOME bugzilla: http://bugzilla.gnome.org/show_bug.cgi?id=491191 Unfortunately it seems like they do not allow CCing to unknown email addresses :/
Thanks for reporting upstream. I added gnome@gentoo.org instead :)
Fixed in CVS ... our fault :) Please reopen if it still fails.