I downgraded xorg-x11 from the latest modular version to 6.8.2-r6. libXdmcp was not installed for some reason, and other programs started complaining. I unmerged and remerged xorg-x11, but it still wasn't installed. Reproducible: Always Steps to Reproduce: 1. Downgrade from Modular xorg-x11 2. emerge xorg-x11 Actual Results: libXdmcp was not installed Expected Results: This library should have been installed by the xorg-x11 ebuild.
6.8.2 does not build a shared version of libXdmcp, only static. You will need to rebuild any packages that linked against a shared libXdmcp.