anchor.diff:      "opus"
       "snappy"
       "zlib"
  -    # "re2" # fails with linker errors
  -    # "harfbuzz-ng" # in versions over 63 harfbuzz and freetype are being built together
  -                    # so we can't build with one from system and other from source
     ];
   
     opusWithCustomModes = libopus.override {
  
positive.code:       sed -i -e '/libpci_loader.*Load/s!"\(libpci\.so\)!"${pciutils}/lib/\1!' \
          gpu/config/gpu_info_collector_linux.cc
  
        sed -i -re 's/([^:])\<(isnan *\()/\1std::\2/g' \
          chrome/browser/ui/webui/engagement/site_engagement_ui.cc
  
        sed -i -e '/#include/ {
          i #include <algorithm>
          :l; n; bl
        }' gpu/config/gpu_control_list.cc
  
        # Allow to put extensions into the system-path.
        sed -i -e 's,/usr,/run/current-system/sw,' chrome/common/chrome_paths.cc
  
        patchShebangs .
        # use our own nodejs
        mkdir -p third_party/node/linux/node-linux-x64/bin
        ln -s $(which node) third_party/node/linux/node-linux-x64/bin/node
  
        # remove unused third-party
        # in third_party/crashpad third_party/zlib contains just a header-adapter
        for lib in ${toString gnSystemLibraries}; do
          find -type f -path "*third_party/$lib/*"     \
              \! -path "*third_party/crashpad/crashpad/third_party/zlib/*"  \
              \! -path "*third_party/$lib/chromium/*"  \
              \! -path "*third_party/$lib/google/*"    \
              \! -path "*base/third_party/icu/*"       \
              \! -path "*base/third_party/libevent/*"  \
              \! -regex '.*\.\(gn\|gni\|isolate\|py\)' \
              -delete
        done
      '' + optionalString stdenv.isAarch64 ''
        substituteInPlace build/toolchain/linux/BUILD.gn \
          --replace 'toolprefix = "aarch64-linux-gnu-"' 'toolprefix = ""'
      '' + optionalString stdenv.cc.isClang ''
        mkdir -p third_party/llvm-build/Release+Asserts/bin
        ln -s ${stdenv.cc}/bin/clang              third_party/llvm-build/Release+Asserts/bin/clang
        ln -s ${stdenv.cc}/bin/clang++            third_party/llvm-build/Release+Asserts/bin/clang++
        ln -s ${llvmPackages.llvm}/bin/llvm-ar    third_party/llvm-build/Release+Asserts/bin/llvm-ar
      '';
  
      gnFlags = mkGnFlags ({
        use_lld = false;
        use_gold = stdenv.buildPlatform.is64bit;  # ld.gold outs-of-memory on i686
        gold_path = "${stdenv.cc}/bin";
        is_debug = false;
  
        proprietary_codecs = false;
  
negative.code:     libevent expat libjpeg snappy
      libpng libcap
      xdg_utils minizip libwebp
      libusb1 re2
      ffmpeg libxslt libxml2
      nasm
    ];
  
    # build paths and release info
  