anchor.diff:      EOF
     '';
   
  -  NIX_CFLAGS_LINK = stdenv.lib.optionalString stdenv.isDarwin
  -                      "-headerpad_max_install_names";
  -
     enableParallelBuilding = true;
   
  -  buildInputs = [ icu expat zlib bzip2 python ]
  -    ++ stdenv.lib.optional stdenv.isDarwin fixDarwinDylibNames;
  +  buildInputs = [ icu expat zlib bzip2 python2 ];
   
     configureScript = "./bootstrap.sh";
     configureFlags = commonConfigureFlags ++ [
       "--with-icu=${icu}"
  -    "--with-python=${python.interpreter}"
  +    "--with-python=${python2.interpreter}"
     ] ++ optional (toolset != null) "--with-toolset=${toolset}";
   
     buildPhase = builder nativeB2Args;
  
positive.code: { stdenv, icu, expat, zlib, bzip2, python, fixDarwinDylibNames
  , toolset ? if stdenv.cc.isClang then "clang" else null
  , enableRelease ? true
  , enableDebug ? false
  
negative.code:     installPhase = installer crossB2Args;
      postFixup = fixup;
    };
  
    meta = {
      homepage = "http://boost.org/";
      description = "Collection of C++ libraries";
      license = stdenv.lib.licenses.boost;
      platforms = platforms.unix;
      maintainers = with maintainers; [ simons wkennington ];
    };
  }
  