Please remove x11-libs/qt-assistant:4 from deps, rebuilding after 'emerge -C x11-libs/qt-assistant' does not change anything in installed files. Seems bug #343959 was fixed upstream.
+*cppcheck-1.57 (05 Nov 2012) + + 05 Nov 2012; Michael Weber <xmw@gentoo.org> cppcheck-1.56.ebuild, + +cppcheck-1.57.ebuild: + Version bump, remove qt-assistant dep (bug 441822, thanks Nikoli) +