anchor.diff:    outputs = [ "out" "info" ];
   
     nativeBuildInputs = [ perl xz.bin ];
  -  configureFlags =
  -    optional (singleBinary != false)
  +  configureFlags = optional (openssl != null) "--with-openssl"
  +    ++ optional (singleBinary != false)
         ("--enable-single-binary" + optionalString (isString singleBinary) "=${singleBinary}")
       ++ optional hostPlatform.isSunOS "ac_cv_func_inotify_init=no"
       ++ optional withPrefix "--program-prefix=g"
  
positive.code:     ];
  
  
    buildInputs = [ gmp ]
      ++ optional aclSupport acl
      ++ optional attrSupport attr
      ++ optionals hostPlatform.isCygwin [ autoreconfHook texinfo ]   # due to patch
  
negative.code: { stdenv, lib, buildPackages
  , autoreconfHook, texinfo, fetchurl, perl, xz, libiconv, gmp ? null
  , openssl ? null
  , hostPlatform, buildPlatform
  , aclSupport ? false, acl ? null
  , attrSupport ? false, attr ? null
  