anchor.diff:    CXXFLAGS = stdenv.lib.optionalString stdenv.cc.isClang "-std=c++14";
   
     cmakeFlags = [
  -    (mkFlag true "XPDF_HEADERS")
  +    (mkFlag true "UNSTABLE_API_ABI_HEADERS") # previously "XPDF_HEADERS"
       (mkFlag (!minimal) "GLIB")
       (mkFlag (!minimal) "CPP")
       (mkFlag (!minimal) "LIBCURL")
  
positive.code: 
    src = fetchurl {
      url = "${meta.homepage}/poppler-${version}.tar.xz";
      sha256 = "0lfs1b1jfamxl13zbl5n448dqvl9n8frbv8180y7b7kfyaw7wx61";
    };
  
    outputs = [ "out" "dev" ];
  
negative.code: }:
  
  let # beware: updates often break cups-filters build
    version = "0.73.0";
    mkFlag = optset: flag: "-DENABLE_${flag}=${if optset then "on" else "off"}";
  in
  stdenv.mkDerivation rec {
  