WSJT-X/boost/libs/config/test/boost_no_is_abstract.ipp

54 lines
1.4 KiB
Plaintext
Raw Normal View History

// (C) Copyright John Maddock and Dave Abrahams 2002.
// Use, modification and distribution are subject to the
// Boost Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
// See http://www.boost.org/libs/config for most recent version.
// MACRO: BOOST_NO_IS_ABSTRACT
// TITLE: is_abstract implementation technique
// DESCRIPTION: Some compilers can't handle the code used for is_abstract even if they support SFINAE.
namespace boost_no_is_abstract{
#if defined(__CODEGEARC__)
template<class T>
struct is_abstract_test
{
enum{ value = __is_abstract(T) };
};
#else
template<class T>
struct is_abstract_test
{
// Deduction fails if T is void, function type,
// reference type (14.8.2/2)or an abstract class type
// according to review status issue #337
//
template<class U>
static double check_sig(U (*)[1]);
template<class U>
static char check_sig(...);
#ifdef __GNUC__
enum{ s1 = sizeof(is_abstract_test<T>::template check_sig<T>(0)) };
#else
enum{ s1 = sizeof(check_sig<T>(0)) };
#endif
enum{ value = (s1 == sizeof(char)) };
};
#endif
struct non_abstract{};
struct abstract{ virtual void foo() = 0; };
int test()
{
return static_cast<bool>(is_abstract_test<non_abstract>::value) == static_cast<bool>(is_abstract_test<abstract>::value);
}
}