lib.closePropagation

The following is the current implementation of this function.

closePropagationFast = list:
    builtins.map (x: x.val) (builtins.genericClosure {
      startSet = builtins.map (x: {
        key = x.outPath;
        val = x;
      }) (builtins.filter (x: x != null) list);
      operator = item:
        if !builtins.isAttrs item.val then
          [ ]
        else
          builtins.concatMap (x:
            if x != null then [{
              key = x.outPath;
              val = x;
            }] else
              [ ]) ((item.val.propagatedBuildInputs or [ ])
                ++ (item.val.propagatedNativeBuildInputs or [ ]));
    });