Changed functionality so empty arrays/lists when converted to a seq or a tuple expand to nothing.

include/boost/preprocessor/array/to_seq.hpp

@@ -15,19 +15,32 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/array/size.hpp>
+# include <boost/preprocessor/control/if.hpp>
+# include <boost/preprocessor/facilities/empty.hpp>
 # include <boost/preprocessor/tuple/to_seq.hpp>
 #
 # /* BOOST_PP_ARRAY_TO_SEQ */
 #
+#    define BOOST_PP_ARRAY_TO_SEQ(array) \
+		BOOST_PP_IF \
+			( \
+			BOOST_PP_ARRAY_SIZE(array), \
+			BOOST_PP_ARRAY_TO_SEQ_DO, \
+			BOOST_PP_EMPTY \
+			) \
+		(array) \
+/**/
+#
 # if BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MSVC()
-#    define BOOST_PP_ARRAY_TO_SEQ(array) BOOST_PP_ARRAY_TO_SEQ_I(BOOST_PP_TUPLE_TO_SEQ, array)
+#    define BOOST_PP_ARRAY_TO_SEQ_DO(array) BOOST_PP_ARRAY_TO_SEQ_I(BOOST_PP_TUPLE_TO_SEQ, array)
 #    define BOOST_PP_ARRAY_TO_SEQ_I(m, args) BOOST_PP_ARRAY_TO_SEQ_II(m, args)
 #    define BOOST_PP_ARRAY_TO_SEQ_II(m, args) BOOST_PP_CAT(m ## args,)
 # elif BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MWCC()
-#    define BOOST_PP_ARRAY_TO_SEQ(array) BOOST_PP_ARRAY_TO_SEQ_I(array)
+#    define BOOST_PP_ARRAY_TO_SEQ_DO(array) BOOST_PP_ARRAY_TO_SEQ_I(array)
 #    define BOOST_PP_ARRAY_TO_SEQ_I(array) BOOST_PP_TUPLE_TO_SEQ ## array
 # else
-#    define BOOST_PP_ARRAY_TO_SEQ(array) BOOST_PP_TUPLE_TO_SEQ array
+#    define BOOST_PP_ARRAY_TO_SEQ_DO(array) BOOST_PP_TUPLE_TO_SEQ array
 # endif
 #
 # endif

include/boost/preprocessor/array/to_tuple.hpp

@@ -14,9 +14,20 @@
 # define BOOST_PREPROCESSOR_ARRAY_TO_TUPLE_HPP
 #
 # include <boost/preprocessor/array/data.hpp>
+# include <boost/preprocessor/array/size.hpp>
+# include <boost/preprocessor/control/if.hpp>
+# include <boost/preprocessor/facilities/empty.hpp>
 #
 # /* BOOST_PP_ARRAY_TO_TUPLE */
 #
-# define BOOST_PP_ARRAY_TO_TUPLE BOOST_PP_ARRAY_DATA
+#    define BOOST_PP_ARRAY_TO_TUPLE(array) \
+		BOOST_PP_IF \
+			( \
+			BOOST_PP_ARRAY_SIZE(array), \
+			BOOST_PP_ARRAY_DATA, \
+			BOOST_PP_EMPTY \
+			) \
+		(array) \
+/**/
 #
 # endif

include/boost/preprocessor/list/to_array.hpp

@@ -137,6 +137,20 @@
 #
 # /* BOOST_PP_LIST_TO_ARRAY_D */
 #
+# if BOOST_PP_VARIADICS && BOOST_PP_VARIADICS_MSVC && (_MSC_VER <= 1400)
+# define BOOST_PP_LIST_TO_ARRAY_D(d, list) \
+	BOOST_PP_IIF \
+		( \
+		BOOST_PP_LIST_IS_NIL(list), \
+		BOOST_PP_LIST_TO_ARRAY_D_VC8ORLESS_EMPTY, \
+		BOOST_PP_LIST_TO_ARRAY_D_VC8ORLESS_DO \
+		) \
+	(d, list) \
+/**/
+# define BOOST_PP_LIST_TO_ARRAY_D_VC8ORLESS_EMPTY(d, list) (0,())
+# define BOOST_PP_LIST_TO_ARRAY_D_VC8ORLESS_DO(d, list) BOOST_PP_LIST_TO_ARRAY_I(BOOST_PP_WHILE_ ## d, list)
+# else
 # define BOOST_PP_LIST_TO_ARRAY_D(d, list) BOOST_PP_LIST_TO_ARRAY_I(BOOST_PP_WHILE_ ## d, list)
+# endif
 #
 # endif /* BOOST_PREPROCESSOR_LIST_TO_ARRAY_HPP */

include/boost/preprocessor/list/to_tuple.hpp

@@ -16,22 +16,44 @@
 #
 # include <boost/preprocessor/config/config.hpp>
 # include <boost/preprocessor/list/enum.hpp>
+# include <boost/preprocessor/control/iif.hpp>
+# include <boost/preprocessor/facilities/empty.hpp>
 #
 # /* BOOST_PP_LIST_TO_TUPLE */
 #
+# define BOOST_PP_LIST_TO_TUPLE(list) \
+	BOOST_PP_IIF \
+		( \
+		BOOST_PP_LIST_IS_NIL(list), \
+		BOOST_PP_EMPTY, \
+		BOOST_PP_LIST_TO_TUPLE_DO \
+		) \
+	(list) \
+/**/
+#
 # if ~BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_EDG()
-#    define BOOST_PP_LIST_TO_TUPLE(list) (BOOST_PP_LIST_ENUM(list))
+#    define BOOST_PP_LIST_TO_TUPLE_DO(list) (BOOST_PP_LIST_ENUM(list))
 # else
-#    define BOOST_PP_LIST_TO_TUPLE(list) BOOST_PP_LIST_TO_TUPLE_I(list)
+#    define BOOST_PP_LIST_TO_TUPLE_DO(list) BOOST_PP_LIST_TO_TUPLE_I(list)
 #    define BOOST_PP_LIST_TO_TUPLE_I(list) (BOOST_PP_LIST_ENUM(list))
 # endif
 #
 # /* BOOST_PP_LIST_TO_TUPLE_R */
 #
+# define BOOST_PP_LIST_TO_TUPLE_R(r, list) \
+	BOOST_PP_IIF \
+		( \
+		BOOST_PP_LIST_IS_NIL(list), \
+		BOOST_PP_EMPTY, \
+		BOOST_PP_LIST_TO_TUPLE_R_DO \
+		) \
+	(r, list) \
+/**/
+#
 # if ~BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_EDG()
-#    define BOOST_PP_LIST_TO_TUPLE_R(r, list) (BOOST_PP_LIST_ENUM_R(r, list))
+#    define BOOST_PP_LIST_TO_TUPLE_R_DO(r, list) (BOOST_PP_LIST_ENUM_R(r, list))
 # else
-#    define BOOST_PP_LIST_TO_TUPLE_R(r, list) BOOST_PP_LIST_TO_TUPLE_R_I(r, list)
+#    define BOOST_PP_LIST_TO_TUPLE_R_DO(r, list) BOOST_PP_LIST_TO_TUPLE_R_I(r, list)
 #    define BOOST_PP_LIST_TO_TUPLE_R_I(r, list) (BOOST_PP_LIST_ENUM_R(r, list))
 # endif
 #