anchor.diff:      #"--disable-atomic"
       "--disable-gcov"
       "--disable-valgrind"
  -    (enFlag "xlib" (xorg != null) null)
  -    (enFlag "xlib-xrender" (xorg != null) null)
  -    (enFlag "xcb" (xorg != null) null)
  -    (enFlag "xlib-xcb" (xorg != null) null)
  -    (enFlag "xcb-shm" (xorg != null) null)
  +    "--${boolEn (xorg != null)}-xlib"
  +    "--${boolEn (xorg != null)}-xlib-xrender"
  +    "--${boolEn (xorg != null)}-xcb"
  +    "--${boolEn (xorg != null)}-xlib-xcb"
  +    "--${boolEn (xorg != null)}-xcb-shm"
       "--disable-qt"
       "--disable-quartz"
       "--disable-quartz-font"
  
positive.code:     "--disable-symbol-lookup"
      #"--enable-some-floating-point"
      "--with-x"
      #(wtFlag "skia" true "yes")
      #(wtFlag "skia-build-type" true "Release")
      "--without-gallium"
    ];
  
  
negative.code: }:
  
  let
    inherit (lib)
      boolEn
      optionalString;
  in
  stdenv.mkDerivation rec {
  