anchor.diff:    # Contains the ruby version heuristics
     rubyVersion = import ./ruby-version.nix { inherit lib; };
   
  +  # Needed during postInstall
  +  buildRuby =
  +    if stdenv.hostPlatform == stdenv.buildPlatform
  +    then "$out/bin/ruby"
  +    else "${buildPackages.ruby}/bin/ruby";
  +
     generic = { version, sha256 }: let
       ver = version;
       tag = ver.gitTag;
  
positive.code:             "--with-out-ext=tk"
              # on yosemite, "generating encdb.h" will hang for a very long time without this flag
              "--with-setjmp-type=setjmp"
            ];
  
          installFlags = stdenv.lib.optionalString docSupport "install-doc";
          # Bundler tries to create this directory
          postInstall = ''
            # Update rubygems
            pushd rubygems
            $out/bin/ruby setup.rb
            popd
  
            # Remove unnecessary groff reference from runtime closure, since it's big
  
negative.code: { stdenv, buildPackages, lib
  , fetchurl, fetchpatch, fetchFromSavannah, fetchFromGitHub
  , zlib, openssl, gdbm, ncurses, readline, groff, libyaml, libffi, autoreconfHook, bison
  , autoconf, darwin ? null
  , buildEnv, bundler, bundix, Foundation
  