While trying to update my Gentoo system with the latest libraries available on the portage sync servers I encountered a terrible conflict that drove me crazy. Finally I fix it and I thought it will be nice to share it with my Internet fellows.
The following command generated the error below:
emerge -pvDuN world
[blocks B] sys-fs/udev ("sys-fs/udev" is blocking sys-apps/systemd-216-r3, sys-apps/gentoo-systemd-integration-4)
[blocks B] sys-apps/gentoo-systemd-integration ("sys-apps/gentoo-systemd-integration" is blocking sys-fs/udev-216)
[blocks B] sys-apps/systemd ("sys-apps/systemd is blocking sys-fs/udev-216)
It turns out that the sys-apps/systemd contains udev and, thus, they hate each other. So you can safely let sys-fs/udev be removed as systemd will be the provider for virtual/udev.
With other words you may uninstall sys-fs/udev BUT make sure you let the virtual/udev installed (or just install it if it's not already). Moreover, make sure you set the systemd FLAG globally (eg. in make.conf).
After doing that I just re-run the emerge command above and so there is no conflict anymore. I can confirm that everything went just fine!
Read more about sys-apps/systemd here.
Now, if you think that this article was interesting don't forget to rate it. It shows me that you care and thus I will continue write about these things.