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Factoring out the workaround to access last variadic parameter.

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Indeed when some parameter are BOOST_PP_EMPTY the last parameter is
accessed correctly but results in a compilation error which doesn't stop
some compiler (e.g. g++) to go through the preprocessing pass and still
compile the binary correctly. But to avoid the error message I used a
workaround which behaves better. I preferred factoring it out to make
clear that there are some reason why this element is strangely accessed.
This commit is contained in:
Damien Buhl (alias daminetreg)
2014-09-23 23:07:00 +02:00
parent 69e67cd1ad
commit aa7b0a6972
1 changed files with 8 additions and 2 deletions
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10
include/boost/fusion/adapted/adt/detail/adapt_base_attr_filler.hpp
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@ -11,6 +11,7 @@
#include <boost/config.hpp> #include <boost/config.hpp>
#include <boost/fusion/adapted/struct/detail/preprocessor/is_seq.hpp> #include <boost/fusion/adapted/struct/detail/preprocessor/is_seq.hpp>
#include <boost/preprocessor/arithmetic/sub.hpp>
#include <boost/preprocessor/control/if.hpp> #include <boost/preprocessor/control/if.hpp>
#include <boost/preprocessor/logical/or.hpp> #include <boost/preprocessor/logical/or.hpp>
#include <boost/preprocessor/empty.hpp> #include <boost/preprocessor/empty.hpp>
@ -53,13 +54,18 @@
BOOST_PP_IS_EMPTY(BOOST_PP_VARIADIC_ELEM(1, __VA_ARGS__))), \ BOOST_PP_IS_EMPTY(BOOST_PP_VARIADIC_ELEM(1, __VA_ARGS__))), \
BOOST_FUSION_ADAPT_ADT_WRAP_ATTR( \ BOOST_FUSION_ADAPT_ADT_WRAP_ATTR( \
BOOST_PP_VARIADIC_ELEM(2, __VA_ARGS__), \ BOOST_PP_VARIADIC_ELEM(2, __VA_ARGS__), \
BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_REST_N(3, \ BOOST_FUSION_WORKAROUND_VARIADIC_EMPTINESS_LAST_ELEM(__VA_ARGS__) \
BOOST_PP_VARIADIC_TO_SEQ(__VA_ARGS__))) ), \ ), \
BOOST_FUSION_ADAPT_ADT_WRAP_ATTR(__VA_ARGS__)) BOOST_FUSION_ADAPT_ADT_WRAP_ATTR(__VA_ARGS__))
# define BOOST_FUSION_ADAPT_ADT_WRAP_ATTR(...) \ # define BOOST_FUSION_ADAPT_ADT_WRAP_ATTR(...) \
((BOOST_PP_VARIADIC_SIZE(__VA_ARGS__), (__VA_ARGS__))) ((BOOST_PP_VARIADIC_SIZE(__VA_ARGS__), (__VA_ARGS__)))
# define BOOST_FUSION_WORKAROUND_VARIADIC_EMPTINESS_LAST_ELEM(...) \
BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_REST_N( \
BOOST_PP_SUB(BOOST_PP_VARIADIC_SIZE(__VA_ARGS__), 1), \
BOOST_PP_VARIADIC_TO_SEQ(__VA_ARGS__)))
#else // BOOST_PP_VARIADICS #else // BOOST_PP_VARIADICS
# define BOOST_FUSION_ADAPT_ADT_FILLER_0(A, B, C, D) \ # define BOOST_FUSION_ADAPT_ADT_FILLER_0(A, B, C, D) \