anchor.diff: -{stdenv, fetchurl, readline ? null, interactive ? false, texinfo ? null, bison}:
  +{stdenv, fetchurl, readline ? null, interactive ? false, texinfo ? null, bison, bashCompletion ? null}:
   
   assert interactive -> readline != null;
   
  
positive.code:   buildNativeInputs = [bison]
      ++ stdenv.lib.optional (texinfo != null) texinfo
      ++ stdenv.lib.optional interactive readline;
     
    postInstall = ''
      # Add an `sh' -> `bash' symlink.
      ln -s bash "$out/bin/sh"
  
      # Install the completion examples.
      ensureDir "$out/etc"
      cp -v "examples/complete/bash_completion" "$out/etc"
  
      ensureDir "$out/etc/bash_completion.d"
      cp -v "examples/complete/complete.gnu-longopt" "$out/etc/bash_completion.d"
    '';
  
    meta = {
      homepage = http://www.gnu.org/software/bash/;
  
negative.code: 
      license = "GPLv3+";
  
      maintainers = [ stdenv.lib.maintainers.ludo stdenv.lib.maintainers.simons ];
    };
  
    passthru = {
  