# emerge -1 --verbose-conflicts --backtrack=100 ncurses
Calculating dependencies... done!
[ebuild  r  U  ] sys-libs/ncurses-6.0-r1 [5.9-r5] USE="{-test%} -threads%"
[ebuild  r  U  ] net-wireless/wpa_supplicant-2.6-r3 [2.5-r1]
[ebuild  rR    ] net-fs/samba-4.5.10-r1
[ebuild  r  U  ] sys-devel/gdb-7.12.1 [7.10.1] USE="xml%*" PYTHON_SINGLE_TARGET="python3_4* -python2_7*"
[ebuild  r  U  ] app-text/aspell-0.60.6.1-r3 [0.60.6.1-r1] L10N="-hu% -hy%" LINGUAS="-de@1901% -hu% -hy%"

!!! Multiple package instances within a single package slot have been pulled
!!! into the dependency graph, resulting in a slot conflict:

sys-libs/ncurses:0

  (sys-libs/ncurses-6.0-r1:0/6::gentoo, ebuild scheduled for merge) pulled in by
    sys-libs/ncurses (Argument)

  (sys-libs/ncurses-5.9-r5:0/5::gentoo, installed) pulled in by
    >=sys-libs/ncurses-5.9-r3:0/5=[abi_x86_64(-)] required by (sys-devel/llvm-3.7.1-r3:0/3.7.1::gentoo, installed)
                             ^^^^^
    >=sys-libs/ncurses-5.2:0/5= required by (sys-apps/less-487:0/0::gentoo, installed)
                          ^^^^^
    sys-libs/ncurses:0/5= required by (sys-apps/openrc-0.32.1:0/0::gentoo, installed)
                    ^^^^^
    sys-libs/ncurses:0/5= required by (dev-lang/ruby-2.3.5:2.3/2.3::gentoo, installed)
                    ^^^^^
    >=sys-libs/ncurses-5.2-r5:0/5= required by (sys-boot/grub-2.02:2/2.02::gentoo, installed)
                             ^^^^^
    >=sys-libs/ncurses-5.7-r7:0/5= required by (sys-apps/gptfdisk-1.0.1:0/0::gentoo, installed)
                             ^^^^^
    sys-libs/ncurses:0/5= required by (dev-util/cmake-3.8.2:0/0::gentoo, installed)
                    ^^^^^
    >=sys-libs/ncurses-5.2-r2:0/5= required by (sys-apps/texinfo-6.3:0/0::gentoo, installed)
                             ^^^^^
    sys-libs/ncurses:0/5= required by (app-text/hunspell-1.6.1-r1:0/1.6::gentoo, installed)
                    ^^^^^
    sys-libs/ncurses:0/5= required by (dev-db/mariadb-10.1.28:0/18::gentoo, installed)
                    ^^^^^
    sys-libs/ncurses:0/5=[unicode] required by (media-video/vlc-2.2.6:0/5-8::gentoo, installed)
                    ^^^^^
    sys-libs/ncurses:0/5= required by (sys-devel/gettext-0.19.8.1:0/0::gentoo, installed)
                    ^^^^^
    >=sys-libs/ncurses-5.7-r7:0/5= required by (media-sound/lame-3.99.5-r1:0/0::gentoo, installed)
                             ^^^^^
    sys-libs/ncurses:0/5= required by (app-crypt/pinentry-0.9.7-r1:0/0::gentoo, installed)
                    ^^^^^
    sys-libs/ncurses:0/5= required by (dev-scheme/guile-1.8.8-r3:12/8::gentoo, installed)
                    ^^^^^
    >=sys-libs/ncurses-5.2-r2:0/5=[unicode] required by (sys-apps/util-linux-2.28.2:0/0::gentoo, installed)
                             ^^^^^
    sys-libs/ncurses:0/5[cxx,gpm,unicode,abi_x86_64(-)] required by (sys-libs/ncurses-5.9-r99:5/5::gentoo, installed)
                    ^^^^


It may be possible to solve this problem by using package.mask to
prevent one of those packages from being selected. However, it is also
possible that conflicting dependencies exist such that they are
impossible to satisfy simultaneously.  If such a conflict exists in
the dependencies of two different packages, then those packages can
not be installed simultaneously.

For more information, see MASKED PACKAGES section in the emerge man
page or refer to the Gentoo Handbook.


The following packages are causing rebuilds:

  (sys-libs/ncurses-6.0-r1:0/6::gentoo, ebuild scheduled for merge) causes rebuilds for:
    (app-text/aspell-0.60.6.1-r3:0/0::gentoo, ebuild scheduled for merge)
    (net-fs/samba-4.5.10-r1:0/0::gentoo, ebuild scheduled for merge)
    (sys-devel/gdb-7.12.1:0/0::gentoo, ebuild scheduled for merge)
    (net-wireless/wpa_supplicant-2.6-r3:0/0::gentoo, ebuild scheduled for merge)

!!! The following installed packages are masked:
- dev-qt/qtwebkit-4.8.6-r1::gentoo (masked by: package.mask)
/usr/portage/profiles/package.mask:
# Andreas Sturmlechner <asturm@gentoo.org> (16 Oct 2017)
# Qt4WebKit is ancient and is likely to have more holes
# in it than swiss cheese. Bug #620684

- app-emulation/vmware-tools-9.9.4.3206955::gentoo (masked by: package.mask)
/usr/portage/profiles/package.mask:
# Thomas Deutschmann <whissi@gentoo.org> (17 Jun 2017)
# Unmaintained in Gentoo repository; Multiple vulnerabilities
# People using VMware in Gentoo should switch to Gentoo's VMware overlay
# Bugs 619398, 621910, 616958, 536364, 614666, 612804 ...

- dev-tex/texmfind-2010.1::gentoo (masked by: package.mask)
/usr/portage/profiles/package.mask:
# Jonas Stein <jstein@gentoo.org> (17 Oct 2017)
# dev-tex/texmfind was superseded by app-portage/pfl
# See also bug #634494. Masked for removal on 2017-11-30

For more information, see the MASKED PACKAGES section in the emerge
man page or refer to the Gentoo Handbook.