x.nix

let
  trace' = t: builtins.trace t t;

  toplevel = rec {
    middle = {
      lower = "hi"; # <---------------------------------------------------,
    }; #                                                                  |
    inherit (middle) lower; # <--------------------------------------,    |
  }; #                                                               |    |
  #                                                                  |    |
  # currently, unsafeGetAttrPos will identify 'lower' is defined at -/    |
  #                                                                       |
  # instead of -----------------------------------------------------------/
  # _POSSIBLY_ even, if possible, it'd be cool to have:
  # {
  #   line = 9;
  #   column = 21;
  #   file = "/home/grahamc/projects/nixpkgs/x.nix";
  #   parent = {
  #     line = 8;
  #     column = 7;
  #     file = "/home/grahamc/projects/nixpkgs/x.nix";
  #     parent = null;
  #   };
  # }
  loc = builtins.unsafeGetAttrPos "lower" toplevel;
in trace' loc