anchor.diff:    enableParallelBuilding = !guileBindings;
   
     buildInputs = [ lzo lzip nettle libtasn1 libidn p11_kit zlib gmp ]
  -    ++ optional stdenv.isLinux trousers
  +    ++ lib.optional (tpmSupport && stdenv.isLinux) trousers
       ++ [ unbound ]
  -    ++ optional guileBindings guile;
  +    ++ lib.optional guileBindings guile;
   
     nativeBuildInputs = [ perl pkgconfig autoreconfHook ];
   
  
positive.code: 
    configureFlags =
      # FIXME: perhaps use $SSL_CERT_FILE instead
      optional stdenv.isLinux "--with-default-trust-store-file=/etc/ssl/certs/ca-certificates.crt"
    ++ [
      "--disable-dependency-tracking"
      "--enable-fast-install"
    ] ++ optionals guileBindings
      [ "--enable-guile" "--with-guile-site-dir=\${out}/share/guile/site" ];
  
    # Build of the Guile bindings is not parallel-safe.  See
  
negative.code: { lib, fetchurl, stdenv, autoreconfHook, zlib, lzo, libtasn1, nettle, pkgconfig, lzip
  , guileBindings, guile, perl, gmp, libidn, p11_kit, unbound
  , tpmSupport ? false, trousers
  
  # Version dependent args
  , version, src, patches ? []
  