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Apply fix for issue https://svn.boost.org/trac/boost/ticket/9910 which provides a C++11 conforming version of is_convertible.

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jzmaddock
2014-04-23 12:50:53 +01:00
parent 3b12bbb0d6
commit f91ab70055
2 changed files with 61 additions and 2 deletions
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42
include/boost/type_traits/is_convertible.hpp
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@ -30,7 +30,9 @@
#if defined(__MWERKS__)
#include <boost/type_traits/remove_reference.hpp>
#endif
#if !defined(BOOST_NO_SFINAE_EXPR) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
# include <boost/utility/declval.hpp>
#endif
#endif // BOOST_IS_CONVERTIBLE
// should be always the last #include directive
@ -52,7 +54,43 @@ namespace boost {
namespace detail {
#if defined(__BORLANDC__) && (__BORLANDC__ < 0x560)
#if !defined(BOOST_NO_SFINAE_EXPR) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
// This is a C++11 conforming version:
template <class A, class B, class C>
struct or_helper
{
static const bool value = (A::value || B::value || C::value);
};
template<typename From, typename To, bool b = or_helper<boost::is_void<From>, boost::is_function<To>, boost::is_array<To> >::value>
struct is_convertible_basic_impl
{
// Nothing converts to function or array, but void converts to void:
static const bool value = is_void<To>::value;
};
template<typename From, typename To>
class is_convertible_basic_impl<From, To, false>
{
typedef char one;
typedef int two;
template<typename To1>
static void test_aux(To1);
template<typename From1, typename To1>
static decltype(test_aux<To1>(boost::declval<From1>()), one()) test(int);
template<typename, typename>
static two test(...);
public:
static const bool value = sizeof(test<From, To>(0)) == 1;
};
#elif defined(__BORLANDC__) && (__BORLANDC__ < 0x560)
//
// special version for Borland compilers
// this version breaks when used for some

21
test/is_convertible_test.cpp
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@ -56,6 +56,20 @@ struct bug_5271b
#endif
#if ((!defined(BOOST_NO_SFINAE_EXPR) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)) || defined(BOOST_IS_CONVERTIBLE)) && !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
struct bug9910
{
bug9910() = default;
bug9910(const bug9910&) = delete; // or private: A(const A&) = default;
};
struct Ref_bug9910
{
// proxy reference to bug9910
operator bug9910& () { return *_ptr; }
bug9910* _ptr;
};
#endif
TT_TEST_BEGIN(is_convertible)
BOOST_CHECK_INTEGRAL_CONSTANT((::tt::is_convertible<Derived,Base>::value), true);
@ -192,5 +206,12 @@ BOOST_CHECK_INTEGRAL_CONSTANT((::tt::is_convertible<int, bug_5271a>::value), fal
BOOST_CHECK_INTEGRAL_CONSTANT((::tt::is_convertible<int, bug_5271b>::value), true);
#endif
#if ((!defined(BOOST_NO_SFINAE_EXPR) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)) || defined(BOOST_IS_CONVERTIBLE)) && !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
#ifndef _MSC_VER
// MSVC gives the wrong answer here, see https://connect.microsoft.com/VisualStudio/feedback/details/858956/std-is-convertible-returns-incorrect-value
BOOST_CHECK_INTEGRAL_CONSTANT((::tt::is_convertible<Ref_bug9910, bug9910>::value), false);
#endif
#endif
TT_TEST_END