sudo apt-get -o Debug::pkgProblemResolveinstall gcc-4.9-base
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 gvfs : Depends: gvfs-daemons (>= 1.20.3-0ubuntu1.2)
        Depends: gvfs-daemons (< 1.20.3-0ubuntu1.2.1~)
 libcheese-gtk23 : Depends: libcheese7 (>= 3.4.0) but it is not going to be installed
                   Depends: libclutter-1.0-0 (>= 1.13.2) but it is not going to be installed
                   Depends: libclutter-gtk-1.0-0 (>= 0.91.8) but it is not going to be installed
                   Depends: libcogl15 (>= 1.15.8) but it is not going to be installed
 libqt5gui5 : Depends: libegl1-mesa (>= 7.8.1) or
                       libegl1-x11
              Depends: libgbm1 (>= 8.1~0) but it is not going to be installed
 libqt5qml5 : Depends: libdouble-conversion1 but it is not going to be installed
 libsoup2.4-1 : Depends: glib-networking (>= 2.32.0) but it is not going to be installed
 libstdc++6 : Depends: gcc-4.9-base (= 4.9.2-10ubuntu13) but 4.9.3-0ubuntu4 is to be installed
 libwebkitgtk-3.0-0 : Depends: libjavascriptcoregtk-3.0-0 (= 2.4.8-1ubuntu1~ubuntu14.04.1) but it is not going to be installed
                      Depends: libenchant1c2a (>= 1.6.0) but it is not going to be installed
                      Depends: libharfbuzz-icu0 (>= 0.9.18) but it is not going to be installed
                      Recommends: gstreamer1.0-plugins-good but it is not going to be installed
 system-config-printer-gnome : Depends: packagekit-system-interface
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.