This project is still in its infancy, but the basic idea is to provide support for C++ and C to Atom-IDE by virtue of the highly experimental LLVM tool, Clangd.
The current implementation should be considered extremely experimental, primarily because Clangd is still under heavy, initial development, and is therefore missing key functionality, contains bugs, etc.
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.