anchor.diff:      cmakeFlags = [
         "-DENABLE_CLI=OFF"
         "-DENABLE_SHARED=OFF"
  +      "-DENABLE_HDR10_PLUS=ON"
         "-DEXPORT_C_API=OFF"
         "-DHIGH_BIT_DEPTH=ON"
         "-DLINKED_8BIT=OFF"
  
positive.code:     rm -v $out/lib/libx265.a
    '';
  
    meta = with stdenv.lib; {
      description = "Library for encoding h.265/HEVC video streams";
      homepage = http://x265.org;
      license = licenses.gpl2;
  
negative.code: let
    inherit (stdenv)
      targetSystem;
    inherit (lib)
      boolOn
      concatStringsSep
      elem
      optionals
      platforms;
  
    sources = {
      "stable" = {
        version = "2.5";
        multihash = "QmSsqLD2yPEuf9CDKgMFEBNSpHYzpE8K2cr6d8aV2icLfB";
        sha256 = "2e53259b504a7edb9b21b9800163b1ff4c90e60c74e23e7001d423c69c5d3d17";
      };
      "head" = {
        fetchzipversion = 3;
        version = "2017-06-21";
        rev = "80c23559084c78c8154ca411ed8e369a07fd7e78";
        sha256 = "074441de68a38488af0f4054292783425abe2a119987785225b2af13ecb44b3c";
      };
    };
    source = sources."${channel}";
  
    src =
      if channel == "head" then
  