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Fixed visitor result type deduction at rvalue ref operators

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This commit is contained in:
Nikita Kniazev
2019-01-03 22:11:47 +03:00
parent 4addd1022a
commit 4b37f9b804
2 changed files with 30 additions and 2 deletions
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include/boost/variant/detail/apply_visitor_unary.hpp
+3 -2
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@@ -108,6 +108,7 @@ apply_visitor(const Visitor& visitor, Visitable& visitable)
#if !defined(BOOST_NO_CXX14_DECLTYPE_AUTO) && !defined(BOOST_NO_CXX11_DECLTYPE_N3276)
#define BOOST_VARIANT_HAS_DECLTYPE_APPLY_VISITOR_RETURN_TYPE
// C++14
namespace detail { namespace variant {
@@ -125,14 +126,14 @@ struct result_multideduce1 {
struct deduce_impl {
typedef typename boost::mpl::next<It>::type next_t;
typedef typename boost::mpl::deref<It>::type value_t;
typedef decltype(true ? boost::declval< Visitor& >()( boost::declval< value_t& >() )
typedef decltype(true ? boost::declval< Visitor& >()( boost::declval< value_t >() )
: boost::declval< typename deduce_impl<next_t>::type >()) type;
};
template <class Dummy>
struct deduce_impl<last_it, Dummy> {
typedef typename boost::mpl::deref<last_it>::type value_t;
typedef decltype(boost::declval< Visitor& >()( boost::declval< value_t& >() )) type;
typedef decltype(boost::declval< Visitor& >()( boost::declval< value_t >() )) type;
};
typedef typename deduce_impl<begin_it>::type type;
test/variant_visit_test.cpp
+27
View File
@@ -62,6 +62,22 @@ public:
};
#ifndef BOOST_NO_CXX11_REF_QUALIFIERS //BOOST_NO_CXX11_RVALUE_REFERENCES
struct rvalue_ref_visitor
{
typedef int result_type;
int operator()(udt1&&) const { return 0; }
int operator()(udt2&&) const { return 1; }
};
#endif
#ifdef BOOST_VARIANT_HAS_DECLTYPE_APPLY_VISITOR_RETURN_TYPE
struct rvalue_ref_decltype_visitor
{
int operator()(udt1&&) const { return 0; }
int operator()(udt2&&) const { return 1; }
};
#endif
template <typename Checker, typename Variant>
inline void unary_test(Variant& var, Checker* = 0)
{
@@ -124,6 +140,17 @@ int main()
unary_test< check2_t >(var2);
unary_test< check2_const_t >(cvar2);
#ifndef BOOST_NO_CXX11_REF_QUALIFIERS //BOOST_NO_CXX11_RVALUE_REFERENCES
BOOST_TEST_EQ( (boost::apply_visitor(
rvalue_ref_visitor(),
boost::variant<udt1, udt2>(udt2()))), 1 );
#endif
#ifdef BOOST_VARIANT_HAS_DECLTYPE_APPLY_VISITOR_RETURN_TYPE
BOOST_TEST_EQ( (boost::apply_visitor(
rvalue_ref_decltype_visitor(),
boost::variant<udt1, udt2>(udt2()))), 1 );
#endif
//
// binary tests
//