Is it possible to have autocompletion, linter, etc. on project' libraries in CLion?

Hello!
As in title - is it possible to have autocompletion, linting and etc. for library files in CLion? Whenever I open any of them, i get the info: “This file does not belong to any project target, code insight features might not work properly”.

On the other hand, main.cpp in src folder works perfectly (includes, etc).

Thanks for any info!