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: { stdenv, lib, buildPackages
  , autoreconfHook, texinfo, fetchurl, perl, xz, libiconv, gmp ? null
  , hostPlatform, buildPlatform
  , aclSupport ? false, acl ? null
  , attrSupport ? false, attr ? null
  
negative.code: 
    # Saw random failures like ‘help2man: can't get '--help' info from
    # man/sha512sum.td/sha512sum’.
    enableParallelBuilding = true;
  
    NIX_LDFLAGS = optionalString selinuxSupport "-lsepol";
    FORCE_UNSAFE_CONFIGURE = optionalString hostPlatform.isSunOS "1";
  