emerge -DNuav @world

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild R ] dev-libs/libpcre-8.36:3 USE="bzip2 cxx jit pcre16* readline recursion-limit (unicode) zlib -libedit -pcre32 -static-libs" ABI_X86="(64) -32 (-x32)" 1,498 kB
[ebuild NS ] dev-qt/qtcore-5.4.0:5 [4.8.6-r1:4] USE="icu -debug -systemd {-test}" 45,029 kB
[ebuild U ] dev-util/boost-build-1.56.0-r1000 [1.55.0-r1000] USE="python -examples {-test}" PYTHON_SINGLE_ABI="2.7 -2.6" 92,557 kB
[ebuild U ] dev-libs/boost-1.56.0-r1000:0/1.56.0 [1.55.0-r1000:0/1.55.0] USE="icu nls python threads -c++11 -context -debug -doc -mpi -static-libs -tools" ABI_X86="(64) -32 (-x32)" PYTHON_ABIS="2.7 3.3 -2.6 -3.1 -3.2 -3.4 (-3.5)" 0 kB
[ebuild U ] app-crypt/qca-2.1.0.3:2 [2.0.3:2] USE="openssl%* qt4%* -botan% -debug -doc -examples -gcrypt% -gpg% -logger% -nss% -pkcs11% -qt5% -sasl% -softstore% {-test%} (-aqua%)" 670 kB
[ebuild U ] app-cdr/cdrtools-3.01_alpha27 [3.01_alpha25] USE="acl filecaps nls unicode" 2,031 kB
[ebuild NS ] dev-qt/qtgui-5.4.0:5 [4.8.6-r1:4] USE="gif harfbuzz jpeg opengl png udev xcb -accessibility -debug -egl -eglfs -evdev -gles2 -ibus -kms {-test}" 0 kB
[ebuild U ] gnome-base/gvfs-1.22.3 [1.22.2] USE="cdda http udev udisks -afp -archive -bluray -fuse -gnome-online-accounts -gphoto2 -gtk -ios -libsecret -mtp -samba -systemd {-test} -zeroconf% (-avahi%*)" 1,551 kB
[blocks B ] app-crypt/qca-gnupg ("app-crypt/qca-gnupg" is blocking app-crypt/qca-2.1.0.3)
[blocks B ] app-crypt/qca-ossl ("app-crypt/qca-ossl" is blocking app-crypt/qca-2.1.0.3)

Total: 8 packages (5 upgrades, 2 in new slots, 1 reinstall), Size of downloads: 143,335 kB
Conflict: 2 blocks (2 unsatisfied)