Что на собеседовании показалось самым сложным

// ty: EMPTY() | typename
#define BOOST_SCOPE_EXIT_AUX_IMPL(id, ty, traits) \
    BOOST_PP_LIST_FOR_EACH_I(BOOST_SCOPE_EXIT_DETAIL_TAG_DECL, id, \
            BOOST_SCOPE_EXIT_AUX_TRAITS_CAPTURES(traits)) \
    BOOST_PP_LIST_FOR_EACH_I(BOOST_SCOPE_EXIT_DETAIL_CAPTURE_DECL, (id, ty), \
            BOOST_SCOPE_EXIT_AUX_TRAITS_CAPTURES(traits)) \
    BOOST_PP_IIF(BOOST_SCOPE_EXIT_AUX_TRAITS_HAS_THIS(traits), \
        BOOST_SCOPE_EXIT_DETAIL_TYPEDEF_TYPEOF_THIS \
    , \
        BOOST_PP_TUPLE_EAT(3) \
    )(id, ty, BOOST_SCOPE_EXIT_AUX_THIS_CAPTURE_T(id)) \
    struct BOOST_SCOPE_EXIT_DETAIL_PARAMS_T(id) { \
        /* interim capture types to workaround internal errors on old GCC */ \
        BOOST_PP_LIST_FOR_EACH_I(BOOST_SCOPE_EXIT_DETAIL_PARAM_DECL, (id, ty), \
                BOOST_SCOPE_EXIT_AUX_TRAITS_CAPTURES(traits)) \
        BOOST_PP_EXPR_IIF(BOOST_SCOPE_EXIT_AUX_TRAITS_HAS_THIS(traits), \
            typedef BOOST_SCOPE_EXIT_AUX_THIS_CAPTURE_T(id) \
                    BOOST_SCOPE_EXIT_AUX_THIS_T(id) ; \
        ) \
        BOOST_PP_LIST_FOR_EACH_I(BOOST_SCOPE_EXIT_AUX_MEMBER, id, \
                BOOST_SCOPE_EXIT_AUX_TRAITS_CAPTURES(traits)) \
        BOOST_PP_EXPR_IIF(BOOST_SCOPE_EXIT_AUX_TRAITS_HAS_THIS(traits), \
            BOOST_SCOPE_EXIT_AUX_THIS_T(id) \
                    BOOST_SCOPE_EXIT_DETAIL_PARAM_THIS(id) ; \
        ) \
        BOOST_SCOPE_EXIT_AUX_PARAMS_T_CTOR(id, ty, \
                BOOST_SCOPE_EXIT_AUX_TRAITS_CAPTURES(traits), \
                BOOST_SCOPE_EXIT_AUX_TRAITS_HAS_THIS(traits)) \
    } BOOST_SCOPE_EXIT_AUX_PARAMS(id) \
        BOOST_SCOPE_EXIT_AUX_PARAMS_INIT(id, \
                BOOST_SCOPE_EXIT_AUX_TRAITS_CAPTURES(traits), \
                BOOST_SCOPE_EXIT_AUX_TRAITS_HAS_THIS(traits)) \
    ; \
    ::boost::scope_exit::detail::declared< \
        ::boost::scope_exit::detail::resolve< \
            sizeof(BOOST_SCOPE_EXIT_AUX_ARGS) \
        >::cmp1<0>::cmp2 \
    > BOOST_SCOPE_EXIT_AUX_ARGS; \
    BOOST_SCOPE_EXIT_AUX_ARGS.value = &BOOST_SCOPE_EXIT_AUX_PARAMS(id); \
    struct BOOST_SCOPE_EXIT_AUX_GUARD_T(id) { \
        BOOST_SCOPE_EXIT_DETAIL_PARAMS_T(id)* boost_se_params_; \
        BOOST_SCOPE_EXIT_AUX_GUARD_T(id) (void* boost_se_params) \
            : boost_se_params_( \
                    (BOOST_SCOPE_EXIT_DETAIL_PARAMS_T(id)*)boost_se_params) \
        {} \
        ~BOOST_SCOPE_EXIT_AUX_GUARD_T(id)() { \
            boost_se_body( \
                BOOST_PP_LIST_FOR_EACH_I(BOOST_SCOPE_EXIT_AUX_ARG, id, \
                        BOOST_SCOPE_EXIT_AUX_TRAITS_CAPTURES(traits)) \
                BOOST_PP_COMMA_IF(BOOST_PP_BITAND(BOOST_PP_LIST_IS_CONS( \
                        BOOST_SCOPE_EXIT_AUX_TRAITS_CAPTURES(traits)), \
                        BOOST_SCOPE_EXIT_AUX_TRAITS_HAS_THIS(traits))) \
                BOOST_PP_EXPR_IIF(BOOST_SCOPE_EXIT_AUX_TRAITS_HAS_THIS( \
                        traits), \
                    boost_se_params_->BOOST_SCOPE_EXIT_DETAIL_PARAM_THIS(id) \
                ) \
            ); \
        } \
        static void boost_se_body( \
            BOOST_PP_LIST_FOR_EACH_I(BOOST_SCOPE_EXIT_AUX_ARG_DECL, (id, ty), \
                    BOOST_SCOPE_EXIT_AUX_TRAITS_CAPTURES(traits)) \
            BOOST_PP_COMMA_IF(BOOST_PP_BITAND(BOOST_PP_LIST_IS_CONS( \
                    BOOST_SCOPE_EXIT_AUX_TRAITS_CAPTURES(traits)), \
                    BOOST_SCOPE_EXIT_AUX_TRAITS_HAS_THIS(traits))) \
            BOOST_PP_EXPR_IIF(BOOST_SCOPE_EXIT_AUX_TRAITS_HAS_THIS(traits), \
                ty BOOST_SCOPE_EXIT_DETAIL_PARAMS_T(id):: \
                        BOOST_SCOPE_EXIT_AUX_THIS_T(id) this_ \
            ) \
        )