Specifically, I needed to manually install sys-apps/dbus in order for the build to complete. # emerge --info Portage 2.3.69 (python 3.6.9-final-0, default/linux/amd64/17.0/desktop/plasma/systemd, gcc-8.3.0, glibc-2.29-r2, 4.19.66-gentoo x86_64) ================================================================= System uname: Linux-4.19.66-gentoo-x86_64-Intel-R-_Core-TM-_i5_CPU_M_540_@_2.53GHz-with-gentoo-2.6 KiB Mem: 7956984 total, 1600356 free KiB Swap: 7340024 total, 4261820 free Timestamp of repository gentoo: Sun, 08 Dec 2019 19:00:01 +0000 Head commit of repository gentoo: c71204fcda467d8b916abd223d30a355332721a4 sh bash 4.4_p23-r1 ld GNU ld (Gentoo 2.32 p2) 2.32.0 distcc 3.3.2 x86_64-pc-linux-gnu [enabled] ccache version 3.7.4 [disabled] app-shells/bash: 4.4_p23-r1::gentoo dev-java/java-config: 2.2.0-r4::gentoo dev-lang/perl: 5.30.1::gentoo dev-lang/python: 2.7.16::gentoo, 3.5.5::gentoo, 3.6.9::gentoo dev-util/ccache: 3.7.4::gentoo dev-util/cmake: 3.14.6::gentoo dev-util/pkgconfig: 0.29.2::gentoo sys-apps/baselayout: 2.6-r1::gentoo sys-apps/sandbox: 2.13::gentoo sys-devel/autoconf: 2.13-r1::gentoo, 2.69-r4::gentoo sys-devel/automake: 1.16.1-r1::gentoo sys-devel/binutils: 2.32-r1::gentoo sys-devel/gcc: 8.3.0-r1::gentoo, 9.2.0-r2::gentoo sys-devel/gcc-config: 2.1::gentoo sys-devel/libtool: 2.4.6-r3::gentoo sys-devel/make: 4.2.1-r4::gentoo sys-kernel/linux-headers: 4.19::gentoo (virtual/os-headers) sys-libs/glibc: 2.29-r2::gentoo Repositories: gentoo location: /home/gentoo/portage sync-type: rsync sync-uri: rsync://rsync.gentoo.org/gentoo-portage priority: -1000 sync-rsync-extra-opts: sync-rsync-verify-jobs: 1 sync-rsync-verify-max-age: 24 sync-rsync-verify-metamanifest: yes localrepo location: /usr/local/portage masters: gentoo ACCEPT_KEYWORDS="amd64" ACCEPT_LICENSE="* -@EULA" CBUILD="x86_64-pc-linux-gnu" CFLAGS="-O2 -pipe -march=westmere -mtune=westmere -maes" CHOST="x86_64-pc-linux-gnu" CONFIG_PROTECT="/etc /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/revdep-rebuild /etc/sandbox.d /etc/terminfo /etc/texmf/language.dat.d /etc/texmf/language.def.d /etc/texmf/updmap.d /etc/texmf/web2c" CXXFLAGS="-O2 -pipe -march=westmere -mtune=westmere -maes" DISTDIR="/home/gentoo/portage/distfiles" ENV_UNSET="DBUS_SESSION_BUS_ADDRESS DISPLAY GOBIN PERL5LIB PERL5OPT PERLPREFIX PERL_CORE PERL_MB_OPT PERL_MM_OPT XAUTHORITY XDG_CACHE_HOME XDG_CONFIG_HOME XDG_DATA_HOME XDG_RUNTIME_DIR" FCFLAGS="-O2 -pipe" FEATURES="assume-digests binpkg-docompress binpkg-dostrip binpkg-logs config-protect-if-modified distcc distlocks ebuild-locks fixlafiles ipc-sandbox merge-sync multilib-strict news parallel-fetch pid-sandbox preserve-libs protect-owned sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv usersandbox usersync xattr" FFLAGS="-O2 -pipe" GENTOO_MIRRORS="http://lug.mtu.edu/gentoo/ http://mirror.lug.udel.edu/pub/gentoo/" LANG="en_US.utf8" LDFLAGS="-Wl,-O1 -Wl,--as-needed" MAKEOPTS="-j14 -l2" PKGDIR="/home/gentoo/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 --exclude=/.git" PORTAGE_TMPDIR="/home/gentoo/portage_temp" USE="X a52 aac acl acpi activities alsa amd64 berkdb bluetooth branding bzip2 cairo cdda cdr cli crypt cups cxx dbus declarative dri dts dvd dvdr emboss encode exif fam flac fortran gdbm gif gpm gtk iconv icu ipv6 jpeg kde kipi kwallet lcms ldap libnotify libtirpc mad mng mp3 mp4 mpeg multilib ncurses networkmanager nls nptl ogg opengl openmp pam pango pcre pdf phonon plasma png policykit ppds pulseaudio qml qt5 readline sdl seccomp semantic-desktop spell split-usr ssl startup-notification svg systemd tcpd tiff truetype udev udisks unicode upower usb vorbis widgets wxwidgets x264 xattr xcb xcomposite xml xv xvid zlib" ABI_X86="64" ADA_TARGET="gnat_2018" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" 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="karbon sheets words" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" CPU_FLAGS_X86="mmx mmxext sse sse2" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock greis isync itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf skytraq superstar2 timing tsip tripmate tnt ublox ubx" INPUT_DEVICES="evdev synaptics joystick" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LIBREOFFICE_EXTENSIONS="presenter-console presenter-minimizer" NETBEANS_MODULES="apisupport cnd groovy gsf harness ide identity j2ee java mobility nb php profiler soa visualweb webcommon websvccommon xml" OFFICE_IMPLEMENTATION="libreoffice" PHP_TARGETS="php7-2" POSTGRES_TARGETS="postgres10 postgres11" PYTHON_SINGLE_TARGET="python3_6" PYTHON_TARGETS="python2_7 python3_6 python3_8" RUBY_TARGETS="ruby24 ruby25" USERLAND="GNU" VIDEO_CARDS="intel" 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: CC, CPPFLAGS, CTARGET, CXX, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LC_ALL, LINGUAS, PORTAGE_BINHOST, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS
Please attach the entire failing build log to this bug report.
Neither libwnck slots have any references to dbus whatsoever in their source code, so with the build.log still not provided, I can't help here.