dev-cmake/cpm-cmake
A cmake not package manager. Essentially, it's about 'how to do bundled dependencies better', though it sucks when you have anything remotely complex. Arniiiii's fork. Don't use CPM in your projects. I've used it and now regret about it. https://michael.orlitzky.com/articles/motherfuckers_need_package_management.xhtml
Reverse Dependencies
Reverse dependancies are sometimes conditional based on your USE flags, Ebuild version and sometimes other packages. please keep this in mind.