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VC 7.1 has_xxx/SFINAE fix (thanks to Daniel Wallin!)

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[SVN r29583]
This commit is contained in:
Aleksey Gurtovoy
2005-06-15 10:43:23 +00:00
parent bea1c79ed7
commit 50c8cde351
1 changed files with 24 additions and 13 deletions
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37
include/boost/mpl/has_xxx.hpp
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@@ -148,25 +148,36 @@ template<> struct trait<T> \
// MSVC 7.1+
// agurt, 15/jun/05: replace overload-based SFINAE implementation with SFINAE
// applied to partial specialization to fix some apparently random failures
// (thanks to Daniel Wallin for researching this!)
namespace boost { namespace mpl { namespace aux {
template< typename T > struct msvc71_sfinae_helper { typedef void type; };
}}}
# define BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(trait, name, default_) \
template< typename T > struct BOOST_PP_CAT(trait,_wrapper_); \
template< typename T > \
boost::mpl::aux::yes_tag BOOST_PP_CAT(trait,_helper_)( \
BOOST_PP_CAT(trait,_wrapper_)<T> const volatile* \
, BOOST_PP_CAT(trait,_wrapper_)<BOOST_MSVC_TYPENAME T::name>* = 0 \
); \
template< typename T, typename U = void > \
struct BOOST_PP_CAT(trait,_impl_) \
{ \
BOOST_STATIC_CONSTANT(bool, value = false); \
typedef boost::mpl::bool_<value> type; \
}; \
\
boost::mpl::aux::no_tag BOOST_PP_CAT(trait,_helper_)(...); \
template< typename T > \
struct BOOST_PP_CAT(trait,_impl_)< \
T \
, typename boost::mpl::aux::msvc71_sfinae_helper< typename T::name >::type \
> \
{ \
BOOST_STATIC_CONSTANT(bool, value = true); \
typedef boost::mpl::bool_<value> type; \
}; \
\
template< typename T, typename fallback_ = boost::mpl::bool_<default_> > \
struct trait \
: BOOST_PP_CAT(trait,_impl_)<T> \
{ \
typedef BOOST_PP_CAT(trait,_wrapper_)<T> t_; \
BOOST_STATIC_CONSTANT(bool, value = \
sizeof((BOOST_PP_CAT(trait,_helper_))(static_cast<t_*>(0))) \
== sizeof(boost::mpl::aux::yes_tag) \
); \
typedef boost::mpl::bool_<value> type; \
}; \
/**/