build2 is an open-source (MIT), cross-platform build toolchain for developing and packaging C and C++ code. It is a hierarchy of tools that includes the build system, package dependency manager (for package consumption), and project dependency manager (for project development).
CPM is designed to promote small, well-tested, composable C++ modules. CPM allows you to link against multiple different versions of the same static library without symbol conflicts. You can include other C++ modules that may depend on older or newer versions of the same modules...
The project is no longer maintained since 2017. It's still available on GitHub