anchor.diff:  { stdenv
   , fetchurl
  +, lib
   , perl
   
   , pcre
  
positive.code: 
    doCheck = false;
  
    meta = with stdenv.lib; {
      description = "Programs to inspect & manipulate PDF files";
      homepage = http://qpdf.sourceforge.net/;
      license = licenses.artistic2;
  
negative.code: }:
  
  let
    inherit (lib)
      boolEn
      optionals;
  
    version = "7.1.1";
  in
  stdenv.mkDerivation rec {
    name = "qpdf-${version}";
  
    src = fetchurl {
      url = "mirror://sourceforge/qpdf/qpdf/${version}/${name}.tar.gz";
      #sha512Url = "mirror://sourceforge/qpdf/qpdf/${version}/${name}.sha512";
      sha256 = "8a0dbfa000a5c257abbc03721c7be277920fe0fcff08202b61c9c2464eedf2fa";
    };
  
    nativeBuildInputs = [
  