It's probably related to libxfce4ui-4.12.1-r1 built with USE=gtk3. Here's build.log excerpt, attaching full file. /usr/lib/gcc/x86_64-pc-linux-gnu/4.8.4/../../../../lib64/libgdk-3.so: undefined reference to `cairo_surface_set_device_scale' /usr/lib/gcc/x86_64-pc-linux-gnu/4.8.4/../../../../lib64/libgtk-3.so: undefined reference to `cairo_surface_get_device_scale' collect2: error: ld returned 1 exit status Makefile:511: recipe for target 'xfce4-appfinder' failed make[3]: *** [xfce4-appfinder] Error 1 Reproducible: Always Portage 2.2.18 (python 3.3.5-final-0, default/linux/amd64/13.0/desktop, gcc-4.8.4, glibc-2.20-r2, 3.17.7-gentoo x86_64) ================================================================= System uname: Linux-3.17.7-gentoo-x86_64-AMD_Athlon-tm-_X4_750K_Quad_Core_Processor-with-gentoo-2.2 KiB Mem: 8118020 total, 1848788 free KiB Swap: 0 total, 0 free Timestamp of repository gentoo: Wed, 13 May 2015 18:00:01 +0000 sh bash 4.2_p53 ld GNU ld (Gentoo 2.24 p1.4) 2.24 app-shells/bash: 4.2_p53::gentoo dev-lang/perl: 5.20.2::gentoo dev-lang/python: 2.7.9-r1::gentoo, 3.3.5-r1::gentoo, 3.4.1::gentoo dev-util/cmake: 2.8.12.2-r1::gentoo dev-util/pkgconfig: 0.28-r2::gentoo sys-apps/baselayout: 2.2::gentoo sys-apps/openrc: 0.13.11::gentoo sys-apps/sandbox: 2.6-r1::gentoo sys-devel/autoconf: 2.13::gentoo, 2.69::gentoo sys-devel/automake: 1.11.6-r1::gentoo, 1.13.4::gentoo sys-devel/binutils: 2.24-r3::gentoo sys-devel/gcc: 4.6.3::gentoo, 4.7.3-r1::gentoo, 4.8.4::gentoo sys-devel/gcc-config: 1.7.3::gentoo sys-devel/libtool: 2.4.6::gentoo sys-devel/make: 4.1-r1::gentoo sys-kernel/linux-headers: 3.18::gentoo (virtual/os-headers) sys-libs/glibc: 2.20-r2::gentoo Repositories: gentoo location: /usr/portage sync-type: rsync sync-uri: rsync://h/gentoo-portage priority: -1000 gamerlay location: /usr/portage/local/layman/gamerlay masters: gentoo priority: 0 sunrise location: /usr/portage/local/layman/sunrise masters: gentoo priority: 1 x11 location: /usr/portage/local/layman/x11 masters: gentoo priority: 2 Local location: /usr/portage/local masters: gentoo priority: 3 Installed sets: @system ACCEPT_KEYWORDS="amd64" ACCEPT_LICENSE="* -@EULA" CBUILD="x86_64-pc-linux-gnu" CFLAGS="-O2 -march=native -pipe" CHOST="x86_64-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/lib64/libreoffice/program/sofficerc /usr/share/config /usr/share/gnupg/qualified.txt" CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/dconf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/init.d /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo /etc/texmf/language.dat.d /etc/texmf/language.def.d /etc/texmf/updmap.d /etc/texmf/web2c /etc/xdg" CXXFLAGS="-O2 -march=native -pipe" DISTDIR="/usr/portage/distfiles" EMERGE_DEFAULT_OPTS="--quiet-build=n" FCFLAGS="-O2 -pipe" FEATURES="assume-digests binpkg-logs distlocks ebuild-locks fixlafiles merge-sync news parallel-fetch preserve-libs protect-owned sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv usersandbox usersync" FFLAGS="-O2 -pipe" GENTOO_MIRRORS="http://gentoo.mirror.pw.edu.pl/ http://gentoo.mneisen.org/ ftp://ftp.snt.utwente.nl/pub/os/linux/gentoo" LANG="pl_PL.UTF-8" LDFLAGS="-Wl,-O1 -Wl,--sort-common -Wl,--as-needed" MAKEOPTS="-j4" PKGDIR="/usr/portage/packages" PORTAGE_CONFIGROOT="/" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --omit-dir-times --compress --force --whole-file --delete --stats --human-readable --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages" PORTAGE_TMPDIR="/mnt/fallout/inne/portage" USE="X a52 aac acoustid acpi alsa amd64 bash-completion berkdb branding bzip2 cairo cdda cdr cli consolekit cracklib cups cxx dbus dri dts dvd dvdr emboss emeral encode exif firefox flac fortran gdbm gif gimp glamor gpm gtk gtk3 iconv icu jpeg kpathsea lcms libnotify mad mmx mmxext mng modules mp3 mp4 mpeg multilib musepack musicbrainz ncurses nls nptl offensive ogg opencl opengl openmp opus pam pango pcre pdf png policykit postscript ppds qt3support qt4 readline sane scanner sdl session smp spell sse sse2 sse3 sse4a ssl ssse3 startup-notification svg system-jpeg system-libvpx system-sqlite tcpd tetex threads tiff truetype udev udisks unicode usb userlocales vaapi vorbis wxwidgets x264 xcb xft xml xmp xv xvid zlib" ABI_X86="64" ALSA_CARDS="intel8x0 emu10k1 virtuoso" APACHE2_MODULES="authn_core authz_core socache_shmcb unixd actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" CALLIGRA_FEATURES="kexi words flow plan sheets stage tables krita karbon braindump author" CAMERAS="ptp2" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" CPU_FLAGS_X86="aes avx fma3 fma4 mmx mmxext popcnt sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3 xop" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf superstar2 timing tsip tripmate tnt ublox ubx" INPUT_DEVICES="evdev" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LIBREOFFICE_EXTENSIONS="presenter-console presenter-minimizer" LIRC_DEVICES="serial" OFFICE_IMPLEMENTATION="libreoffice" PHP_TARGETS="php5-5" PYTHON_SINGLE_TARGET="python2_7" PYTHON_TARGETS="python2_7 python3_3" RUBY_TARGETS="ruby19 ruby20" SANE_BACKENDS="pixma" USERLAND="GNU" VIDEO_CARDS="fglrx radeon r600 nvidia nv nouveau" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq steal rawnat logmark ipmark dhcpmac delude chaos account" Unset: CPPFLAGS, CTARGET, INSTALL_MASK, LC_ALL, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS, USE_PYTHON
Created attachment 403212 [details] build.log
It seems to be a problem between x11-libs/gtk+:3 and x11-libs/cairo. Did you try to rebuild x11-libs/gtk+:3 and try again?
The problem seems to have resolved itself. I didn't re-emerge gtk+:3 in the meantime, but I did update cairo to cairo-1.14.2.