anchor.diff:  
     patches = [
       ./sw_vers.patch
  -
  -    # Fix builtin_llvm=OFF support
  -    (fetchpatch {
  -      url = "https://github.com/root-project/root/commit/0cddef5d3562a89fe254e0036bb7d5ca8a5d34d2.diff";
  -      excludes = [ "interpreter/cling/tools/plugins/clad/CMakeLists.txt" ];
  -      sha256 = "sha256-VxWUbxRHB3O6tERFQdbGI7ypDAZD3sjSi+PYfu1OAbM=";
  -    })
     ];
   
     # Fix build against vanilla LLVM 9
  
positive.code: , noSplash ? false
  }:
  
  stdenv.mkDerivation rec {
    pname = "root";
    version = "6.24.06";
  
    src = fetchurl {
      url = "https://root.cern.ch/download/root_v${version}.source.tar.gz";
      sha256 = "sha256-kH9p9LrKHk8w7rSXlZjKdZm2qoA8oEboDiW2u6oO9SI=";
    };
  
    nativeBuildInputs = [ makeWrapper cmake pkg-config git ];
  
negative.code:     zstd
      lapack
      libxml2
      _llvm_9
      lz4
      xz
      gsl
  