anchor.diff:    inherit (stdenv.lib)
       optionals
       optionalString;
  +
  +  tarballUrls = version: [
  +    "https://fedorahosted.org/releases/e/l/elfutils/${version}/elfutils-${version}.tar.bz2"
  +    "mirror://gentoo/elfutils-${version}.tar.bz2"
  +  ];
   in
   
   stdenv.mkDerivation rec {
  
positive.code:     "--disable-sanitize-undefined"
    ];
  
    meta = with stdenv.lib; {
      description = "Libraries/utilities to handle ELF objects";
      homepage = https://fedorahosted.org/elfutils/;
  
negative.code:   version = "0.166";
  
    src = fetchurl {
      urls = tarballUrls version;
      allowHashOutput = false;
      sha256 = "3c056914c8a438b210be0d790463b960fc79d234c3f05ce707cbff80e94cba30";
    };
  
  