12:44 < myself_> pacman -Su :: The following packages should be upgraded first :     pacman :: Do you want to cancel the current operation :: and upgrade 
                 these packages now? [Y/n]   resolving dependencies... looking for inter-conflicts... error: failed to prepare transaction (could not 
                 satisfy dependencies) :: gcc: requires gcc-libs=4.7.1-4
12:45 < myself_> any ideas?
12:49 < mtjm> wouldn't trust it to keep pacman working if updating it first (broke it multiple times when I used this option); try n?
12:51 < myself_> Ha, looks like a way to go!
12:53 < mtjm> maybe report a bug?  updating pacman first seems a mostly wrong default (it's not the first report of problems with it here)

The cases I remember were mips64el libarchive (changing soname) and glibc (adding new versions of symbols used by pacman) updates. Using the "broken" priority since this configuration default does result in a broken pacman after some updates.