All channel registrations and user accounts on Freenode have been deleted and have to be registered again. As most other projects we have moved to Libera.Chat:
server: irc.libera.chat
channel: #cmake
help website: https://libera.chat/
Note to Kitware staff: I’m the channel founder I shamefully forgot was so nice to register the channel early and hand it over to me as I was operator on Freenode, too. If any of you wants to take over the channel or just become operator just contact me.