I got the following annoying little error after I tried to upgrade to a newer mod_python on my Gentoo Linux box:

libtool: compile: unable to infer tagged configuration

It seems that the main problem was due to the fact that I’ve switched to GCC 4.1.1 and when compiling mod_python, the compilation uses libtool that is brought and compiled with Apache (located under /usr/share/apr-0/build/) which should have been recompiled after I’ve upgraded to the new GCC (I was too lazy to continue running the “emerge -e system” command so I stopped it after GCC was recompiled).

To solve it, simple recompile Apache and emerge upgrade mod_python.