emerge --sync && emerge -avuDN worldAnd when that was (finally) done, I ran:
emerge -av --depcleanWhich uninstalled a bunch of packages. The problem came when I ran:
revdep-rebuild -- -avNothing would emerge. Nothing. Every package I tried to emerge would end in the error:
configure: error: C compiler cannot create executablesThe root problem turned out to be a bug with the way that the gcc ebuild updates from certain versions. Portage was configured to use a compiler version that no longer existed on the system. The solution was to run:
binutils-config -l binutils-config num gcc-config -l gcc-config numWhere num above is the numerical selection of one of the items on the list output by the previous command. My gcc-config selection told me when I selected it that it had a bug with GCC_SPECS and to re-emerge it, so I did that. I probably didn't have to, but it's good to be cautious and I had a few hours to kill (this is a 1GHz Pentium III system). After that, I was good to go.