anchor.diff:      "--disable-gtk-doc"
       "--disable-gtk-doc-html"
       "--disable-gtk-doc-pdf"
  -    (enFlag "introspection" (gobject-introspection != null) null)
  -    (enFlag "vala" (vala != null) null)
  +    "--enable-introspection"
  +    "--${boolEn (vala != null)}-vala"
       "--disable-update-mime"
       "--disable-update-icon-cache"
       "--disable-debug"
  
positive.code: 
    doCheck = false;
  
    meta = with stdenv.lib; {
      description = "Libraries for cryptographic UIs and accessing PKCS#11 modules";
      homepage = https://git.gnome.org/browse/gcr;
      license = with licenses; [
  
negative.code: }:
  
  let
    inherit (lib)
      boolEn;
  
    versionMajor = "3.20";
    versionMinor = "0";
    version = "${versionMajor}.${versionMinor}";
  in
  stdenv.mkDerivation rec {
    name = "gcr-${version}";
  
    src = fetchurl {
      url = "mirror://gnome/sources/gcr/${versionMajor}/${name}.tar.xz";
  