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Partly fixed fusion::fold regression for MSVC <=8.

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It implicitly includes MSVC 9's workaround.
This commit is contained in:
Kohei Takahashi
2015-11-13 20:03:12 +09:00
parent bb8b5afc7f
commit 0c18e85ecd
1 changed files with 23 additions and 4 deletions
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27
include/boost/fusion/algorithm/iteration/detail/fold.hpp
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@ -46,23 +46,42 @@ namespace boost { namespace fusion
{ {
namespace detail namespace detail
{ {
template<int SeqSize, typename It, typename State, typename F, typename = void> template<int SeqSize, typename It, typename State, typename F, typename = void
#if BOOST_WORKAROUND(BOOST_MSVC, < 1500)
// Dirty hack: those compilers cannot choose exactly one partial specialization.
, bool = SeqSize == 0
#endif
>
struct BOOST_PP_CAT(result_of_it_,BOOST_FUSION_FOLD_NAME) struct BOOST_PP_CAT(result_of_it_,BOOST_FUSION_FOLD_NAME)
{}; {};
template<typename It, typename State, typename F> template<typename It, typename State, typename F>
struct BOOST_PP_CAT(result_of_it_,BOOST_FUSION_FOLD_NAME)<0,It,State,F struct BOOST_PP_CAT(result_of_it_,BOOST_FUSION_FOLD_NAME)<0,It,State,F
, typename boost::enable_if_has_type<typename State::type>::type> , typename boost::enable_if_has_type<typename State::type>::type
#if BOOST_WORKAROUND(BOOST_MSVC, < 1500)
, true
#endif
>
{ {
typedef typename State::type type; typedef typename State::type type;
}; };
template<int SeqSize, typename It, typename State, typename F> template<int SeqSize, typename It, typename State, typename F>
struct BOOST_PP_CAT(result_of_it_,BOOST_FUSION_FOLD_NAME)<SeqSize,It,State,F struct BOOST_PP_CAT(result_of_it_,BOOST_FUSION_FOLD_NAME)<SeqSize,It,State,F
// MSVC9 issues a compile error as a partial specialization is ambiguous.
, typename boost::enable_if_has_type< , typename boost::enable_if_has_type<
#if BOOST_WORKAROUND(BOOST_MSVC, == 1500)
// Following SFINAE enables to avoid MSVC 9's partial specialization
// ambiguous bug but MSVC 8 don't compile, and moreover MSVC 8 style
// workaround won't work with MSVC 9.
typename boost::disable_if_c<SeqSize == 0, State>::type::type typename boost::disable_if_c<SeqSize == 0, State>::type::type
>::type> #else
typename State::type
#endif
>::type
#if BOOST_WORKAROUND(BOOST_MSVC, < 1500)
, false
#endif
>
: BOOST_PP_CAT(result_of_it_,BOOST_FUSION_FOLD_NAME)< : BOOST_PP_CAT(result_of_it_,BOOST_FUSION_FOLD_NAME)<
SeqSize-1 SeqSize-1
, typename result_of::BOOST_FUSION_FOLD_IMPL_NEXT_IT_FUNCTION<It>::type , typename result_of::BOOST_FUSION_FOLD_IMPL_NEXT_IT_FUNCTION<It>::type