anchor.diff:  
   stdenv.mkDerivation rec {
     pname = "nvidia-texture-tools";
  -  version = "unstable-2019-10-27";
  +  version = "unstable-2020-12-21";
   
     src = fetchFromGitHub {
       owner = "castano";
       repo = "nvidia-texture-tools";
  -    rev = "a131e4c6b0b7c9c73ccc3c9e6f1c7e165be86bcc";
  -    sha256 = "1qzyr3ib5dpxyq1y33lq02qv4cww075sm9bm4f651d34q5x38sk3";
  +    rev = "aeddd65f81d36d8cb7b169b469ef25156666077e";
  +    sha256 = "sha256-BYNm8CxPQbfmnnzNmOQ2Dc8HSyO8mkqzYsBZ5T80398=";
     };
  -
  -  patches = [
  -    (fetchpatch {
  -      url = "https://github.com/castano/nvidia-texture-tools/commit/6474f2593428d89ec152da2502aa136ababe66ca.patch";
  -      sha256 = "0akbkvm55hiv58jx71h9hj173rbnqlb5a430y9azjiix7zga42vd";
  -    })
  -  ];
   
     nativeBuildInputs = [ cmake ];
   
  
positive.code:     # Make a recently added pure virtual function just virtual,
      # to keep compatibility.
      sed -i 's/virtual void endImage() = 0;/virtual void endImage() {}/' src/nvtt/nvtt.h
    '';
  
    cmakeFlags = [
  
negative.code:     homepage = "https://github.com/castano/nvidia-texture-tools";
      license = licenses.mit;
      platforms = platforms.unix;
      maintainers = with maintainers; [ wegank ];
    };
  }
  