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

Calculating dependencies... done!

emerge: there are no ebuilds built with USE flags to satisfy ">=x11-libs/qt-sql-4.7.0:4[qt3support]".
!!! One of the following packages is required to complete your request:
- x11-libs/qt-sql-4.7.2 (Change USE: +qt3support)
(dependency required by "kde-base/ksysguard-4.6.2-r1" [ebuild])
(dependency required by "kde-base/kdebase-meta-4.6.2" [ebuild])
(dependency required by "@selected" [set])
(dependency required by "@world" [argument])

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

Calculating dependencies... done!
[ebuild     U ] x11-libs/qt-core-4.7.2-r1 [4.6.3-r1] USE="exceptions glib iconv jit%* ssl (-aqua) -debug -optimized-qmake -pch -private-headers% -qt3support* (-doc%)" 0 kB
[uninstall    ] x11-libs/qt-dbus-4.6.3  USE="exceptions (-aqua) -debug -pch"
[blocks b     ] <x11-libs/qt-dbus-4.7.2 ("<x11-libs/qt-dbus-4.7.2" is blocking x11-libs/qt-core-4.7.2-r1)
[uninstall    ] x11-libs/qt-gui-4.6.3-r2  USE="accessibility cups dbus exceptions glib mng qt3support (-aqua) -debug -gtk -nas -nis -pch -raster -tiff -trace -xinerama"
[blocks b     ] <x11-libs/qt-gui-4.7.2 ("<x11-libs/qt-gui-4.7.2" is blocking x11-libs/qt-core-4.7.2-r1)
[uninstall    ] x11-libs/qt-script-4.6.3  USE="exceptions iconv (-aqua) -debug -pch"
[blocks b     ] <x11-libs/qt-script-4.7.2 ("<x11-libs/qt-script-4.7.2" is blocking x11-libs/qt-core-4.7.2-r1)
[uninstall    ] x11-libs/qt-multimedia-4.6.3  USE="exceptions iconv (-aqua) -debug -pch"
[blocks b     ] <x11-libs/qt-multimedia-4.7.2 ("<x11-libs/qt-multimedia-4.7.2" is blocking x11-libs/qt-core-4.7.2-r1)
[uninstall    ] x11-libs/qt-svg-4.6.3  USE="exceptions iconv (-aqua) -debug -pch"
[blocks b     ] <x11-libs/qt-svg-4.7.2 ("<x11-libs/qt-svg-4.7.2" is blocking x11-libs/qt-core-4.7.2-r1)
[uninstall    ] x11-libs/qt-opengl-4.6.3  USE="exceptions qt3support (-aqua) -debug -pch"
[blocks b     ] <x11-libs/qt-opengl-4.7.2 ("<x11-libs/qt-opengl-4.7.2" is blocking x11-libs/qt-core-4.7.2-r1)
[uninstall    ] x11-libs/qt-xmlpatterns-4.6.3  USE="(-aqua) -debug -pch"
[blocks b     ] <x11-libs/qt-xmlpatterns-4.7.2 ("<x11-libs/qt-xmlpatterns-4.7.2" is blocking x11-libs/qt-core-4.7.2-r1)
[blocks B     ] <x11-libs/qt-test-4.7.2 ("<x11-libs/qt-test-4.7.2" is blocking x11-libs/qt-core-4.7.2-r1)
[blocks B     ] <x11-libs/qt-qt3support-4.7.2 ("<x11-libs/qt-qt3support-4.7.2" is blocking x11-libs/qt-core-4.7.2-r1)
[blocks B     ] <x11-libs/qt-webkit-4.7.2 ("<x11-libs/qt-webkit-4.7.2" is blocking x11-libs/qt-core-4.7.2-r1)
[blocks B     ] <x11-libs/qt-sql-4.7.2 ("<x11-libs/qt-sql-4.7.2" is blocking x11-libs/qt-core-4.7.2-r1)
[blocks B     ] >x11-libs/qt-core-4.6.3-r9999 (">x11-libs/qt-core-4.6.3-r9999" is blocking x11-libs/qt-qt3support-4.6.3, x11-libs/qt-test-4.6.3, x11-libs/qt-gui-4.6.3-r2, x11-libs/qt-svg-4.6.3, x11-libs/qt-opengl-4.6.3, x11-libs/qt-dbus-4.6.3, x11-libs/qt-script-4.6.3, x11-libs/qt-webkit-4.6.3-r1, x11-libs/qt-sql-4.6.3-r2, x11-libs/qt-multimedia-4.6.3, x11-libs/qt-xmlpatterns-4.6.3)

Total: 1 package (1 upgrade, 7 uninstalls), Size of downloads: 0 kB
Conflict: 12 blocks (5 unsatisfied)

* Error: The above package list contains packages which cannot be
* installed at the same time on the same system.

  (x11-libs/qt-sql-4.6.3-r2, installed) pulled in by
    x11-libs/qt-sql required by @selected

  (x11-libs/qt-core-4.7.2-r1, ebuild scheduled for merge) pulled in by
    qt-core

For more information about Blocked Packages, please refer to the following
section of the Gentoo Linux x86 Handbook (architecture is irrelevant):

http://www.gentoo.org/doc/en/handbook/h … =1#blocked