anchor.diff:  , expat, libcap, oniguruma, libdwarf, libmcrypt, tbb, gperftools, glog, libkrb5
   , bzip2, openldap, readline, libelf, uwimap, binutils, cyrus_sasl, pam, libpng
   , libxslt, ocaml, freetype, gdb, git, perl, mariadb, gmp, libyaml, libedit
  -, libvpx, imagemagick, fribidi
  +, libvpx, imagemagick, fribidi, gperf
   }:
   
   stdenv.mkDerivation rec {
     name    = "hhvm-${version}";
  -  version = "3.6.0";
  +  version = "3.12.1";
   
     # use git version since we need submodules
     src = fetchgit {
       url    = "https://github.com/facebook/hhvm.git";
  -    rev    = "6ef13f20da20993dc8bab9eb103f73568618d3e8";
  -    sha256 = "29a2d4b56cfd348b199d8f90b4e4b07de85dfb2ef1538479cd1e84f5bc1fbf96";
  +    rev    = "f516f1bb9046218f89885a220354c19dda6d8f4d";
  +    sha256 = "1jdw6j394z7ksg4wdcnm7lkcs7iam5myx6k18w8hr595s1dfk3sj";
       fetchSubmodules = true;
     };
   
  
positive.code:       libevent gd curl libxml2 icu flex bison openssl zlib php expat libcap
        oniguruma libdwarf libmcrypt tbb gperftools bzip2 openldap readline
        libelf uwimap binutils cyrus_sasl pam glog libpng libxslt ocaml libkrb5
        gmp libyaml libedit libvpx imagemagick fribidi
      ];
  
    enableParallelBuilding = false;
    dontUseCmakeBuildDir = true;
    NIX_LDFLAGS = "-lpam -L${pam}/lib";
    MYSQL_INCLUDE_DIR="${mariadb}/include/mysql";
  
negative.code:       --replace /bin/bash ${stdenv.shell}
      substituteInPlace ./configure \
        --replace "/usr/bin/env bash" ${stdenv.shell}
      perl -pi -e 's/([ \t(])(isnan|isinf)\(/$1std::$2(/g' \
        hphp/runtime/base/*.cpp \
        hphp/runtime/ext/std/*.cpp \
        hphp/runtime/ext_zend_compat/php-src/main/*.cpp \
        hphp/runtime/ext_zend_compat/php-src/main/*.h
      patchShebangs .
    '';
  
    cmakeFlags = [ "-DCMAKE_BUILD_TYPE=Release" ];
  