The submission title is strongly misleading. From the page:

  Unlike most other programming languages that encapsulate the
  build system, package dependency manager, and project
  dependency manager into a single tool (such as Rust's cargo
  or Go's go), build2 is a hierarchy of several tools that
  you will be using directly and which together with your
  version control system (VCS) will constitute the core
  of your project management toolset.