anchor.diff:          sha256 = "40b8204a8c97e95913c31d11dc58527780e866424c5dd577f9a8ee2209612209";
         };
   
  +      nativeBuildInputs = [
  +        python2Packages.lxml
  +        python2Packages.python
  +      ];
  +
  +      postPatch = ''
  +        sed -i xml/genglvnd.py \
  +          -e 's,drafts/,,'
  +      '';
  +
         configurePhase = ":";
   
         buildPhase = ''
  +        # Some headers such as glx.h are not pre-generated, regenerate all
  +        # to be sure none are missing.
  +        pushd xml
  +          python genheaders.py
  +        popd
  +        pushd api
  +          for header in glcorearb.h glext.h gl.h; do
  +            python ../xml/genglvnd.py -registry ../xml/gl.xml GL/$header.h
  +          done
  +        popd
  +
           tar -Jcvf opengl-headers-${version}.tar.xz api/
         '';
   
  
positive.code:   name = "opengl-headers-${version}";
  
    src = fetchurl {
      url = "http://opengl-headers.tar.xz";
      multihash = "QmZvWAAPb4FAB4psCuvfKZW1N638AFG7ZTLX1Jr4kRE8UB";
      sha256 = "77172528da0549cebdaf4f5f129e020bfad722fdf9808f5e32d14766c2e81081";
    };
  
    configurePhase = ":";
  
negative.code: , fetchurl
  , fetchFromGitHub
  , lib
  , python2Packages
  }:
  
  # TODO: build release tarballs, repo vendors pdfs
  