anchor.diff:            nativeBuildInputs = nativeBuildInputs ++ (if crossConfig == null then buildInputs else []);
             propagatedNativeBuildInputs = propagatedNativeBuildInputs ++
               (if crossConfig == null then propagatedBuildInputs else []);
  -        }))) (
  +        })) (
         {
           # The meta attribute is passed in the resulting attribute set,
           # but it's not part of the actual derivation, i.e., it's not
  
positive.code:         # include it in the result, it *is* available to nix-env for
          # queries.  We also a meta.position attribute here to
          # identify the source location of the package.
          meta = attrs.meta or {} // (if pos != null then {
            position = pos.file + ":" + (toString pos.line);
          } else {});
          passthru = attrs.passthru or {};
        } //
        # Pass through extra attributes that are not inputs, but
        # should be made available to Nix expressions using the
        # derivation (e.g., in assertions).
        (attrs.passthru or {}));
  
    # The stdenv that we are producing.
    result =
  
negative.code: 
    # Add a utility function to produce derivations that use this
    # stdenv and its shell.
    mkDerivation =
      { buildInputs ? []
      , nativeBuildInputs ? []
      , propagatedBuildInputs ? []
      , propagatedNativeBuildInputs ? []
      , crossConfig ? null
      , meta ? {}
      , passthru ? {}
      , ... } @ attrs:
      let
        pos =
          if attrs.meta.description or null != null then
  