In C++20 variadic data can be empty. This means that BOOST_PP_VARIADIC_SIZE now returns 0 for empty data instead of 1, and that conversions to and from empty variadic data and lists or arrays, which can be empty, work properly.

2020-06-29 21:57:23 -04:00
parent ffb26db146
commit 3ac4c915a3
14 changed files with 173 additions and 16 deletions
--- a/include/boost/preprocessor/array/enum.hpp
+++ b/include/boost/preprocessor/array/enum.hpp
@ -15,11 +15,27 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
+# include <boost/preprocessor/array/size.hpp>
 # include <boost/preprocessor/tuple/rem.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 #
 # /* BOOST_PP_ARRAY_ENUM */
 #
-# if BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MSVC()
+# if BOOST_PP_VARIADIC_HAS_OPT()
+#    if BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MSVC()
+#        define BOOST_PP_ARRAY_ENUM_NOT_EMPTY(array) BOOST_PP_ARRAY_ENUM_I(BOOST_PP_TUPLE_REM_CTOR, array)
+#        define BOOST_PP_ARRAY_ENUM_I(m, args) BOOST_PP_ARRAY_ENUM_II(m, args)
+#        define BOOST_PP_ARRAY_ENUM_II(m, args) BOOST_PP_CAT(m ## args,)
+#    elif BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MWCC()
+#        define BOOST_PP_ARRAY_ENUM_NOT_EMPTY(array) BOOST_PP_ARRAY_ENUM_I(array)
+#        define BOOST_PP_ARRAY_ENUM_I(array) BOOST_PP_TUPLE_REM_CTOR ## array
+#    else
+#        define BOOST_PP_ARRAY_ENUM_NOT_EMPTY(array) BOOST_PP_TUPLE_REM_CTOR array
+#    endif
+#    define BOOST_PP_ARRAY_ENUM_EMPTY(array)
+#    define BOOST_PP_ARRAY_ENUM(array) BOOST_PP_IF(BOOST_PP_ARRAY_SIZE(array),BOOST_PP_ARRAY_ENUM_NOT_EMPTY,BOOST_PP_ARRAY_ENUM_EMPTY)(array)
+# elif BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MSVC()
 #    define BOOST_PP_ARRAY_ENUM(array) BOOST_PP_ARRAY_ENUM_I(BOOST_PP_TUPLE_REM_CTOR, array)
 #    define BOOST_PP_ARRAY_ENUM_I(m, args) BOOST_PP_ARRAY_ENUM_II(m, args)
 #    define BOOST_PP_ARRAY_ENUM_II(m, args) BOOST_PP_CAT(m ## args,)
--- a/include/boost/preprocessor/list/enum.hpp
+++ b/include/boost/preprocessor/list/enum.hpp
@ -15,12 +15,24 @@
 # define BOOST_PREPROCESSOR_LIST_ENUM_HPP
 #
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/iif.hpp>
+# include <boost/preprocessor/list/adt.hpp>
 # include <boost/preprocessor/list/for_each_i.hpp>
 # include <boost/preprocessor/punctuation/comma_if.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 #
 # /* BOOST_PP_LIST_ENUM */
 #
-# if ~BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_EDG()
+# if BOOST_PP_VARIADIC_HAS_OPT()
+#    if ~BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_EDG()
+#        define BOOST_PP_LIST_ENUM_NOT_EMPTY(list) BOOST_PP_LIST_FOR_EACH_I(BOOST_PP_LIST_ENUM_O, BOOST_PP_NIL, list)
+#    else
+#        define BOOST_PP_LIST_ENUM_NOT_EMPTY(list) BOOST_PP_LIST_ENUM_I(list)
+#        define BOOST_PP_LIST_ENUM_I(list) BOOST_PP_LIST_FOR_EACH_I(BOOST_PP_LIST_ENUM_O, BOOST_PP_NIL, list)
+#    endif
+#    define BOOST_PP_LIST_ENUM_EMPTY(list)
+#    define BOOST_PP_LIST_ENUM(list) BOOST_PP_IIF(BOOST_PP_LIST_IS_NIL(list),BOOST_PP_LIST_ENUM_EMPTY,BOOST_PP_LIST_ENUM_NOT_EMPTY)(list)
+# elif ~BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_EDG()
 #    define BOOST_PP_LIST_ENUM(list) BOOST_PP_LIST_FOR_EACH_I(BOOST_PP_LIST_ENUM_O, BOOST_PP_NIL, list)
 # else
 #    define BOOST_PP_LIST_ENUM(list) BOOST_PP_LIST_ENUM_I(list)
--- a/include/boost/preprocessor/tuple/reverse.hpp
+++ b/include/boost/preprocessor/tuple/reverse.hpp
@ -17,9 +17,11 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
 # include <boost/preprocessor/facilities/overload.hpp>
 # include <boost/preprocessor/tuple/size.hpp>
 # include <boost/preprocessor/variadic/size.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 #
 # /* BOOST_PP_TUPLE_REVERSE */
 #
@ -31,7 +33,12 @@
 #        define BOOST_PP_TUPLE_REVERSE_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_REVERSE_, BOOST_PP_TUPLE_SIZE(tuple)) tuple
 #    else
 #        define BOOST_PP_TUPLE_REVERSE(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_REVERSE_O_, __VA_ARGS__)(__VA_ARGS__)
-#        define BOOST_PP_TUPLE_REVERSE_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_REVERSE_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        if BOOST_PP_VARIADIC_HAS_OPT()
+#            define BOOST_PP_TUPLE_REVERSE_O_1(tuple) BOOST_PP_TUPLE_REVERSE_O_1_SIZE(BOOST_PP_VARIADIC_SIZE tuple,tuple)
+#            define BOOST_PP_TUPLE_REVERSE_O_1_SIZE(size,tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_REVERSE_, BOOST_PP_IF(size,size,1)) tuple
+#        else
+#            define BOOST_PP_TUPLE_REVERSE_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_REVERSE_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        endif
 #    endif
 #    define BOOST_PP_TUPLE_REVERSE_O_2(size, tuple) BOOST_PP_TUPLE_REVERSE_O_1(tuple)
 # else
--- a/include/boost/preprocessor/tuple/size.hpp
+++ b/include/boost/preprocessor/tuple/size.hpp
@ -15,10 +15,19 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 # include <boost/preprocessor/variadic/size.hpp>
 #
 # if BOOST_PP_VARIADICS
-#    if BOOST_PP_VARIADICS_MSVC
+#    if BOOST_PP_VARIADIC_HAS_OPT()
+#        if BOOST_PP_VARIADICS_MSVC
+#            define BOOST_PP_TUPLE_SIZE(tuple) BOOST_PP_TUPLE_SIZE_CHECK(BOOST_PP_CAT(BOOST_PP_VARIADIC_SIZE tuple,))
+#        else
+#            define BOOST_PP_TUPLE_SIZE(tuple) BOOST_PP_TUPLE_SIZE_CHECK(BOOST_PP_VARIADIC_SIZE tuple)
+#        endif
+#        define BOOST_PP_TUPLE_SIZE_CHECK(size) BOOST_PP_IF(size,size,1)
+#    elif BOOST_PP_VARIADICS_MSVC
 #        define BOOST_PP_TUPLE_SIZE(tuple) BOOST_PP_CAT(BOOST_PP_VARIADIC_SIZE tuple,)
 #    else
 #        define BOOST_PP_TUPLE_SIZE(tuple) BOOST_PP_VARIADIC_SIZE tuple
--- a/include/boost/preprocessor/tuple/to_array.hpp
+++ b/include/boost/preprocessor/tuple/to_array.hpp
@ -15,9 +15,11 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
 # include <boost/preprocessor/facilities/overload.hpp>
 # include <boost/preprocessor/tuple/size.hpp>
 # include <boost/preprocessor/variadic/size.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 #
 # /* BOOST_PP_TUPLE_TO_ARRAY */
 #
@ -29,7 +31,12 @@
 #        define BOOST_PP_TUPLE_TO_ARRAY_1(tuple) (BOOST_PP_TUPLE_SIZE(tuple), tuple)
 #    else
 #        define BOOST_PP_TUPLE_TO_ARRAY(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_TO_ARRAY_, __VA_ARGS__)(__VA_ARGS__)
-#        define BOOST_PP_TUPLE_TO_ARRAY_1(tuple) (BOOST_PP_VARIADIC_SIZE tuple, tuple)
+#        if BOOST_PP_VARIADIC_HAS_OPT()
+#            define BOOST_PP_TUPLE_TO_ARRAY_1(tuple) BOOST_PP_TUPLE_TO_ARRAY_1_SIZE(BOOST_PP_VARIADIC_SIZE tuple, tuple)
+#            define BOOST_PP_TUPLE_TO_ARRAY_1_SIZE(size,tuple) (BOOST_PP_IF(size,size,1), tuple)
+#        else
+#            define BOOST_PP_TUPLE_TO_ARRAY_1(tuple) (BOOST_PP_VARIADIC_SIZE tuple, tuple)
+#        endif
 #    endif
 #    define BOOST_PP_TUPLE_TO_ARRAY_2(size, tuple) (size, tuple)
 # else
--- a/include/boost/preprocessor/tuple/to_list.hpp
+++ b/include/boost/preprocessor/tuple/to_list.hpp
@ -17,9 +17,11 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
 # include <boost/preprocessor/facilities/overload.hpp>
 # include <boost/preprocessor/tuple/size.hpp>
 # include <boost/preprocessor/variadic/size.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 #
 # /* BOOST_PP_TUPLE_TO_LIST */
 #
@ -31,7 +33,12 @@
 #        define BOOST_PP_TUPLE_TO_LIST_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_LIST_, BOOST_PP_TUPLE_SIZE(tuple)) tuple
 #    else
 #        define BOOST_PP_TUPLE_TO_LIST(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_TO_LIST_O_, __VA_ARGS__)(__VA_ARGS__)
-#        define BOOST_PP_TUPLE_TO_LIST_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_LIST_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        if BOOST_PP_VARIADIC_HAS_OPT()
+#            define BOOST_PP_TUPLE_TO_LIST_O_1(tuple) BOOST_PP_TUPLE_TO_LIST_O_1_SIZE(BOOST_PP_VARIADIC_SIZE tuple, tuple)
+#            define BOOST_PP_TUPLE_TO_LIST_O_1_SIZE(size,tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_LIST_, BOOST_PP_IF(size,size,1)) tuple
+#        else
+#            define BOOST_PP_TUPLE_TO_LIST_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_LIST_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        endif
 #    endif
 #    define BOOST_PP_TUPLE_TO_LIST_O_2(size, tuple) BOOST_PP_TUPLE_TO_LIST_O_1(tuple)
 # else
--- a/include/boost/preprocessor/tuple/to_seq.hpp
+++ b/include/boost/preprocessor/tuple/to_seq.hpp
@ -15,9 +15,11 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
 # include <boost/preprocessor/facilities/overload.hpp>
 # include <boost/preprocessor/tuple/size.hpp>
 # include <boost/preprocessor/variadic/size.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 #
 # /* BOOST_PP_TUPLE_TO_SEQ */
 #
@ -29,7 +31,12 @@
 #        define BOOST_PP_TUPLE_TO_SEQ_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_SEQ_, BOOST_PP_TUPLE_SIZE(tuple)) tuple
 #    else
 #        define BOOST_PP_TUPLE_TO_SEQ(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_TO_SEQ_O_, __VA_ARGS__)(__VA_ARGS__)
-#        define BOOST_PP_TUPLE_TO_SEQ_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_SEQ_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        if BOOST_PP_VARIADIC_HAS_OPT()
+#            define BOOST_PP_TUPLE_TO_SEQ_O_1(tuple) BOOST_PP_TUPLE_TO_SEQ_O_1_SIZE(BOOST_PP_VARIADIC_SIZE tuple, tuple)
+#            define BOOST_PP_TUPLE_TO_SEQ_O_1_SIZE(size,tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_SEQ_, BOOST_PP_IF(size,size,1)) tuple
+#        else
+#            define BOOST_PP_TUPLE_TO_SEQ_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_SEQ_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        endif
 #    endif
 #    define BOOST_PP_TUPLE_TO_SEQ_O_2(size, tuple) BOOST_PP_TUPLE_TO_SEQ_O_1(tuple)
 # else
--- a/include/boost/preprocessor/variadic/size.hpp
+++ b/include/boost/preprocessor/variadic/size.hpp
@ -15,14 +15,24 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/iif.hpp>
+# include <boost/preprocessor/facilities/check_empty.hpp>
 #
 # /* BOOST_PP_VARIADIC_SIZE */
 #
 # if BOOST_PP_VARIADICS
-#    if BOOST_PP_VARIADICS_MSVC
-#        define BOOST_PP_VARIADIC_SIZE(...) BOOST_PP_CAT(BOOST_PP_VARIADIC_SIZE_I(__VA_ARGS__, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1,),)
+#    if BOOST_PP_VARIADIC_HAS_OPT()
+#       if BOOST_PP_VARIADICS_MSVC
+#           define BOOST_PP_VARIADIC_SIZE_NOT_EMPTY(...) BOOST_PP_CAT(BOOST_PP_VARIADIC_SIZE_I(__VA_ARGS__, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1,),)
+#       else
+#           define BOOST_PP_VARIADIC_SIZE_NOT_EMPTY(...) BOOST_PP_VARIADIC_SIZE_I(__VA_ARGS__, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1,)
+#       endif
+#       define BOOST_PP_VARIADIC_SIZE_EMPTY(...) 0
+#       define BOOST_PP_VARIADIC_SIZE(...) BOOST_PP_IIF(BOOST_PP_CHECK_EMPTY(__VA_ARGS__),BOOST_PP_VARIADIC_SIZE_EMPTY,BOOST_PP_VARIADIC_SIZE_NOT_EMPTY)(__VA_ARGS__)
+#    elif BOOST_PP_VARIADICS_MSVC
+#       define BOOST_PP_VARIADIC_SIZE(...) BOOST_PP_CAT(BOOST_PP_VARIADIC_SIZE_I(__VA_ARGS__, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1,),)
 #    else
-#        define BOOST_PP_VARIADIC_SIZE(...) BOOST_PP_VARIADIC_SIZE_I(__VA_ARGS__, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1,)
+#       define BOOST_PP_VARIADIC_SIZE(...) BOOST_PP_VARIADIC_SIZE_I(__VA_ARGS__, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1,)
 #    endif
 #    define BOOST_PP_VARIADIC_SIZE_I(e0, e1, e2, e3, e4, e5, e6, e7, e8, e9, e10, e11, e12, e13, e14, e15, e16, e17, e18, e19, e20, e21, e22, e23, e24, e25, e26, e27, e28, e29, e30, e31, e32, e33, e34, e35, e36, e37, e38, e39, e40, e41, e42, e43, e44, e45, e46, e47, e48, e49, e50, e51, e52, e53, e54, e55, e56, e57, e58, e59, e60, e61, e62, e63, size, ...) size
 # endif
--- a/include/boost/preprocessor/variadic/to_array.hpp
+++ b/include/boost/preprocessor/variadic/to_array.hpp
@ -14,15 +14,23 @@
 # define BOOST_PREPROCESSOR_VARIADIC_TO_ARRAY_HPP
 #
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
 # include <boost/preprocessor/tuple/to_array.hpp>
-# if BOOST_PP_VARIADICS_MSVC
-#    include <boost/preprocessor/variadic/size.hpp>
-# endif
+# include <boost/preprocessor/variadic/has_opt.hpp>
+# include <boost/preprocessor/variadic/size.hpp>
 #
 # /* BOOST_PP_VARIADIC_TO_ARRAY */
 #
 # if BOOST_PP_VARIADICS
-#    if BOOST_PP_VARIADICS_MSVC
+#    if BOOST_PP_VARIADIC_HAS_OPT()
+#        if BOOST_PP_VARIADICS_MSVC
+#            define BOOST_PP_VARIADIC_TO_ARRAY_NON_EMPTY(...) BOOST_PP_TUPLE_TO_ARRAY_2(BOOST_PP_VARIADIC_SIZE(__VA_ARGS__),(__VA_ARGS__))
+#        else
+#            define BOOST_PP_VARIADIC_TO_ARRAY_NON_EMPTY(...) BOOST_PP_TUPLE_TO_ARRAY((__VA_ARGS__))
+#        endif
+#        define BOOST_PP_VARIADIC_TO_ARRAY_EMPTY(...) (0,())
+#        define BOOST_PP_VARIADIC_TO_ARRAY(...) BOOST_PP_IF(BOOST_PP_VARIADIC_SIZE(__VA_ARGS__),BOOST_PP_VARIADIC_TO_ARRAY_NON_EMPTY,BOOST_PP_VARIADIC_TO_ARRAY_EMPTY)(__VA_ARGS__)
+#    elif BOOST_PP_VARIADICS_MSVC
 #        define BOOST_PP_VARIADIC_TO_ARRAY(...) BOOST_PP_TUPLE_TO_ARRAY_2(BOOST_PP_VARIADIC_SIZE(__VA_ARGS__),(__VA_ARGS__))
 #    else
 #        define BOOST_PP_VARIADIC_TO_ARRAY(...) BOOST_PP_TUPLE_TO_ARRAY((__VA_ARGS__))
--- a/include/boost/preprocessor/variadic/to_list.hpp
+++ b/include/boost/preprocessor/variadic/to_list.hpp
@ -14,12 +14,21 @@
 # define BOOST_PREPROCESSOR_VARIADIC_TO_LIST_HPP
 #
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
 # include <boost/preprocessor/tuple/to_list.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
+# include <boost/preprocessor/variadic/size.hpp>
 #
 # /* BOOST_PP_VARIADIC_TO_LIST */
 #
 # if BOOST_PP_VARIADICS
-#    define BOOST_PP_VARIADIC_TO_LIST(...) BOOST_PP_TUPLE_TO_LIST((__VA_ARGS__))
+#    if BOOST_PP_VARIADIC_HAS_OPT()
+#        define BOOST_PP_VARIADIC_TO_LIST_NOT_EMPTY(...) BOOST_PP_TUPLE_TO_LIST((__VA_ARGS__))
+#        define BOOST_PP_VARIADIC_TO_LIST_EMPTY(...) BOOST_PP_NIL
+#        define BOOST_PP_VARIADIC_TO_LIST(...) BOOST_PP_IF(BOOST_PP_VARIADIC_SIZE(__VA_ARGS__),BOOST_PP_VARIADIC_TO_LIST_NOT_EMPTY,BOOST_PP_VARIADIC_TO_LIST_EMPTY)(__VA_ARGS__)
+#    else
+#        define BOOST_PP_VARIADIC_TO_LIST(...) BOOST_PP_TUPLE_TO_LIST((__VA_ARGS__))
+#    endif
 # endif
 #
 # endif