anchor.diff:  , nixosTestRunner ? false
   }:
   
  -with lib;
   let
  -  audio = optionalString alsaSupport "alsa,"
  -    + optionalString pulseSupport "pa,"
  -    + optionalString sdlSupport "sdl,";
  +  audio = lib.optionalString alsaSupport "alsa,"
  +    + lib.optionalString pulseSupport "pa,"
  +    + lib.optionalString sdlSupport "sdl,";
   
   in
   
   stdenv.mkDerivation rec {
  -  version = "6.0.0";
     pname = "qemu"
       + lib.optionalString xenSupport "-xen"
       + lib.optionalString hostCpuOnly "-host-cpu-only"
       + lib.optionalString nixosTestRunner "-for-vm-tests";
  +  version = "6.0.0";
   
     src = fetchurl {
       url= "https://download.qemu.org/qemu-${version}.tar.xz";
  
positive.code:   };
  
    nativeBuildInputs = [ python python.pkgs.sphinx pkg-config flex bison meson ninja ]
      ++ optionals gtkSupport [ wrapGAppsHook ]
      ++ optionals stdenv.isLinux [ autoPatchelfHook ];
    buildInputs =
      [ zlib glib perl pixman
        vde2 texinfo makeWrapper lzo snappy
        gnutls nettle curl
      ]
      ++ optionals ncursesSupport [ ncurses ]
      ++ optionals stdenv.isDarwin [ CoreServices Cocoa Hypervisor rez setfile ]
      ++ optionals seccompSupport [ libseccomp ]
      ++ optionals numaSupport [ numactl ]
      ++ optionals pulseSupport [ libpulseaudio ]
      ++ optionals sdlSupport [ SDL2 SDL2_image ]
      ++ optionals gtkSupport [ gtk3 gettext vte ]
      ++ optionals vncSupport [ libjpeg libpng ]
      ++ optionals smartcardSupport [ libcacard ]
      ++ optionals spiceSupport [ spice-protocol spice ]
      ++ optionals usbredirSupport [ usbredir ]
      ++ optionals stdenv.isLinux [ alsa-lib libaio libcap_ng libcap attr ]
      ++ optionals xenSupport [ xen ]
      ++ optionals cephSupport [ ceph ]
      ++ optionals glusterfsSupport [ glusterfs libuuid ]
      ++ optionals openGLSupport [ mesa epoxy libdrm ]
      ++ optionals virglSupport [ virglrenderer ]
      ++ optionals libiscsiSupport [ libiscsi ]
      ++ optionals smbdSupport [ samba ];
  
    dontUseMesonConfigure = true; # meson's configurePhase isn't compatible with qemu build
  
  
negative.code:     # copy qemu-ga (guest agent) to separate output
      mkdir -p $ga/bin
      cp $out/bin/qemu-ga $ga/bin/
    '' + lib.optionalString gtkSupport ''
      # wrap GTK Binaries
      for f in $out/bin/qemu-system-*; do
        wrapGApp $f
  