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: 
        lib.addPassthru (derivation (
          (removeAttrs attrs ["meta" "passthru" "crossAttrs"])
          // (let
            buildInputs = attrs.buildInputs or [];
            nativeBuildInputs = attrs.nativeBuildInputs or [];
            propagatedBuildInputs = attrs.propagatedBuildInputs or [];
            propagatedNativeBuildInputs = attrs.propagatedNativeBuildInputs or [];
            crossConfig = attrs.crossConfig or null;
          in
          {
            builder = attrs.realBuilder or shell;
            args = attrs.args or ["-e" (attrs.builder or ./default-builder.sh)];
  
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
  