anchor.diff:      cp --no-preserve=mode -r "${contribSrc}/modules" "$NIX_BUILD_TOP/source/opencv_contrib"
     '';
   
  -  patches = [
  -    # https://github.com/opencv/opencv/pull/13232
  -    # This also fixes the test of haskell-opencv HEAD where we got the following error:
  -    # libgomp: Out of memory allocating 927712937064 bytes
  -    (fetchpatch {
  -      url = https://github.com/opencv/opencv/commit/e1ac8589f8a19b9bf5598bbae073ae12721c541d.patch;
  -      sha256 = "1ap2818lixjhc5jgf779c57kwacafc0ap40lqrx6nqfz31silglj";
  -    })
  -  ] ++
  +  patches =
       # Fixes issue: https://github.com/opencv/opencv_contrib/issues/1923
       # PR: https://github.com/opencv/opencv_contrib/pull/1913
       lib.optional buildContrib (fetchpatch {
  
positive.code: }:
  
  let
    version = "4.0.0";
  
    src = fetchFromGitHub {
      owner  = "opencv";
      repo   = "opencv";
      rev    = version;
      sha256 = "1r2hszm4044dfx65wv69rcs419jjd7bqllhnpcwk3n28f5ahln50";
    };
  
    contribSrc = fetchFromGitHub {
      owner  = "opencv";
      repo   = "opencv_contrib";
      rev    = version;
      sha256 = "1g4pzw7hv1v9jp1nrqjxqwpi1byl3mxkj6w6ibq6ydsn0138p66z";
    };
  
  
negative.code:       sha256 = "102mq1qgmla40hhj8mda70inhakdazm9agyah98kq9931scvf0c9";
        stripLen = 2;
        extraPrefix = "opencv_contrib/";
      });
  
    # This prevents cmake from using libraries in impure paths (which
  