anchor.diff:    # for finding the nlopt library, which doesn't pick up the package in the nix store.
     # We need to set the path via the NLOPT environment variable instead.
     NLOPT = nlopt;
  +
  +  # Disable compiler warnings that clutter the build log
  +  # It seems to be a known issue for Eigen:
  +  # http://eigen.tuxfamily.org/bz/show_bug.cgi?id=1221
  +  NIX_CFLAGS_COMPILE = "-Wno-ignored-attributes";
   
     prePatch = ''
       # In nix ioctls.h isn't available from the standard kernel-headers package
  
positive.code:     pkgconfig
    ];
  
    # We could add Eigen, but it doesn't currently compile with the version in
    # nixpkgs.
    buildInputs = [
      boost
      cereal
      curl
      expat
      glew
      libpng
  
negative.code: { stdenv, lib, fetchFromGitHub, makeWrapper, cmake, pkgconfig
  , boost, cereal, curl, eigen, expat, glew, libpng, tbb, wxGTK30
  , gtest, nlopt, xorg, makeDesktopItem
  }:
  let
  