module libc [no_undeclared_includes] {
  module math { header "math.h" export * }
  module stdlib { header "stdlib.h" export * }
  module stddef { header "stddef.h" export * }
  module stdint { header "stdint.h" export * }
  module stdio { header "stdio.h" export * }
  module util { header "util.h" export * }
  module POSIX {
    module sys {
      module types {
        umbrella header "sys/_types/_types.h"
        export *
      }
    }
  }
}