#include <boost/preprocessor/list/adt.hpp>
#define OLD /* ........... */ \
BOOST_PP_LIST_CONS( \
a, \
BOOST_PP_LIST_CONS( \
b, \
BOOST_PP_LIST_CONS( \
c, \
BOOST_PP_LIST_NIL \
) \
) \
) \
/**/
#define NEW (a, (b, (c, BOOST_PP_NIL)))
BOOST_PP_LIST_FIRST(OLD) == BOOST_PP_LIST_FIRST(NEW)
// expands to a == a
BOOST_PP_LIST_REST(OLD) == BOOST_PP_LIST_REST(NEW)
// expands to (b, (c, BOOST_PP_NIL)) == (b, (c, BOOST_PP_NIL))