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https://github.com/boostorg/type_traits.git
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Extracted C++11 implementation of is_nothrow_swappable to a separate header.
Also modified the implementation to avoid referencing any potential swap overloads in namespace boost, unless these overloads are found by ADL. Added tests to verify is_nothrow_swappable works with ADL.
This commit is contained in:
Andrey Semashev
37
include/boost/type_traits/detail/is_swappable_cxx_11.hpp
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37
include/boost/type_traits/detail/is_swappable_cxx_11.hpp
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#ifndef BOOST_TYPE_TRAITS_DETAIL_IS_SWAPPABLE_CXX_11_HPP_INCLUDED
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#define BOOST_TYPE_TRAITS_DETAIL_IS_SWAPPABLE_CXX_11_HPP_INCLUDED
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// Copyright 2017 Peter Dimov
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//
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// Distributed under the Boost Software License, Version 1.0.
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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#include <boost/config.hpp>
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#include <boost/type_traits/declval.hpp>
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#include <boost/type_traits/integral_constant.hpp>
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#if __cplusplus >= 201103L || defined(BOOST_DINKUMWARE_STDLIB)
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#include <utility> // for std::swap (C++11)
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#else
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#include <algorithm> // for std::swap (C++98)
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#endif
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// Intentionally not within boost namespace to avoid implicitly pulling in boost::swap overloads other than through ADL
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namespace boost_type_traits_swappable_detail
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{
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using std::swap;
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template<class T, class U, bool B = noexcept(swap(boost::declval<T>(), boost::declval<U>()))> boost::integral_constant<bool, B> is_nothrow_swappable_with_impl( int );
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template<class T, class U> boost::false_type is_nothrow_swappable_with_impl( ... );
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template<class T, class U>
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struct is_nothrow_swappable_with_helper { typedef decltype( boost_type_traits_swappable_detail::is_nothrow_swappable_with_impl<T, U>(0) ) type; };
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template<class T, bool B = noexcept(swap(boost::declval<T&>(), boost::declval<T&>()))> boost::integral_constant<bool, B> is_nothrow_swappable_impl( int );
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template<class T> boost::false_type is_nothrow_swappable_impl( ... );
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template<class T>
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struct is_nothrow_swappable_helper { typedef decltype( boost_type_traits_swappable_detail::is_nothrow_swappable_impl<T>(0) ) type; };
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} // namespace boost_type_traits_swappable_detail
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#endif // #ifndef BOOST_TYPE_TRAITS_DETAIL_IS_SWAPPABLE_CXX_11_HPP_INCLUDED
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@ -28,35 +28,16 @@ template <class T> struct is_nothrow_swappable_with<T, T> : is_nothrow_swappable
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#else
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#include <boost/type_traits/declval.hpp>
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#include <boost/type_traits/integral_constant.hpp>
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#include <algorithm>
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#include <boost/type_traits/detail/is_swappable_cxx_11.hpp>
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namespace boost
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{
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namespace type_traits_swappable_detail
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{
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using std::swap;
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template<class T, class U, bool B = noexcept(swap(declval<T>(), declval<U>()))> integral_constant<bool, B> is_nothrow_swappable_with_impl( int );
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template<class T, class U> false_type is_nothrow_swappable_with_impl( ... );
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template<class T, class U>
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struct is_nothrow_swappable_with_helper { typedef decltype( type_traits_swappable_detail::is_nothrow_swappable_with_impl<T, U>(0) ) type; };
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template<class T, bool B = noexcept(swap(declval<T&>(), declval<T&>()))> integral_constant<bool, B> is_nothrow_swappable_impl( int );
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template<class T> false_type is_nothrow_swappable_impl( ... );
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template<class T>
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struct is_nothrow_swappable_helper { typedef decltype( type_traits_swappable_detail::is_nothrow_swappable_impl<T>(0) ) type; };
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} // namespace type_traits_swappable_detail
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template<class T, class U> struct is_nothrow_swappable_with: type_traits_swappable_detail::is_nothrow_swappable_with_helper<T, U>::type
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template<class T, class U> struct is_nothrow_swappable_with: boost_type_traits_swappable_detail::is_nothrow_swappable_with_helper<T, U>::type
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{
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};
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template<class T> struct is_nothrow_swappable: type_traits_swappable_detail::is_nothrow_swappable_helper<T>::type
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template<class T> struct is_nothrow_swappable: boost_type_traits_swappable_detail::is_nothrow_swappable_helper<T>::type
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{
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};
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@ -1,4 +1,3 @@
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// Copyright 2017 Peter Dimov
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//
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// Distributed under the Boost Software License, Version 1.0.
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@ -17,6 +16,13 @@
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#include "check_integral_constant.hpp"
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#include <utility>
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// These conditions should be similar to those in is_nothrow_swappable.hpp
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#if defined(BOOST_NO_SFINAE_EXPR) || defined(BOOST_NO_CXX11_NOEXCEPT) || defined(BOOST_NO_CXX11_DECLTYPE) || defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS) \
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|| BOOST_WORKAROUND(BOOST_GCC, < 40700) \
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|| (defined(__GLIBCXX__) && __GLIBCXX__ <= 20120301) // built-in clang++ -std=c++11 on Travis, w/ libstdc++ 4.6
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#define BOOST_TYPE_TRAITS_IS_NOTHROW_SWAPPABLE_EMULATED
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#endif
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struct X
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{
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};
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@ -45,6 +51,44 @@ struct U
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void swap(U&, U&) {}
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#if !defined(BOOST_TYPE_TRAITS_IS_NOTHROW_SWAPPABLE_EMULATED) && !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
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namespace test_ns {
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// Not swappable using std::swap, but swappable using test_ns::swap
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struct only_adl_swappable
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{
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only_adl_swappable(only_adl_swappable const&) = delete;
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only_adl_swappable& operator= (only_adl_swappable const&) = delete;
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};
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inline void swap(only_adl_swappable&, only_adl_swappable&) BOOST_NOEXCEPT {}
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} // namespace test_ns
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namespace boost {
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namespace type_traits_is_nothrow_swappable_test {
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// Some type that is defined within boost namespace and that has a specialized swap overload
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struct swappable
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{
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swappable(swappable const&) = delete;
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swappable& operator= (swappable const&) = delete;
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};
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// This overload should be selected by is_nothrow_swappable
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inline void swap(swappable&, swappable&) BOOST_NOEXCEPT {}
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} // namespace type_traits_is_nothrow_swappable_test
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// Some generic swap implementation, such as the one from Boost.Swap. This overload should *not* be selected by is_nothrow_swappable.
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template< typename T1, typename T2 >
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inline void swap(T1&, T2&) {}
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} // namespace boost
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#endif
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TT_TEST_BEGIN(is_nothrow_swappable)
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<int>::value, true);
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@ -52,9 +96,7 @@ BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<int const>::value, fals
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<int volatile>::value, true);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<int const volatile>::value, false);
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#if defined(BOOST_NO_SFINAE_EXPR) || defined(BOOST_NO_CXX11_NOEXCEPT) || defined(BOOST_NO_CXX11_DECLTYPE) || defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS) \
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|| BOOST_WORKAROUND(BOOST_GCC, < 40700)\
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|| (defined(__GLIBCXX__) && __GLIBCXX__ <= 20120301) // built-in clang++ -std=c++11 on Travis, w/ libstdc++ 4.6
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#if defined(BOOST_TYPE_TRAITS_IS_NOTHROW_SWAPPABLE_EMULATED)
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<int[2]>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<int const[2]>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<int volatile[2]>::value, false);
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@ -71,9 +113,7 @@ BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<void const>::value, fal
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<void volatile>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<void const volatile>::value, false);
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#if defined(BOOST_NO_SFINAE_EXPR) || defined(BOOST_NO_CXX11_NOEXCEPT) || defined(BOOST_NO_CXX11_DECLTYPE) || defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS) \
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|| BOOST_WORKAROUND(BOOST_GCC, < 40700)\
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|| (defined(__GLIBCXX__) && __GLIBCXX__ <= 20120301) // built-in clang++ -std=c++11 on Travis, w/ libstdc++ 4.6
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#if defined(BOOST_TYPE_TRAITS_IS_NOTHROW_SWAPPABLE_EMULATED)
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<X>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<X const>::value, false);
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@ -157,6 +197,30 @@ BOOST_CHECK_INTEGRAL_CONSTANT((::tt::is_nothrow_swappable<std::pair<V, int> cons
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BOOST_CHECK_INTEGRAL_CONSTANT((::tt::is_nothrow_swappable<std::pair<V, int> volatile>::value), false);
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BOOST_CHECK_INTEGRAL_CONSTANT((::tt::is_nothrow_swappable<std::pair<V, int> const volatile>::value), false);
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#if !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<test_ns::only_adl_swappable>::value, true);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<test_ns::only_adl_swappable const>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<test_ns::only_adl_swappable volatile>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<test_ns::only_adl_swappable const volatile>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<test_ns::only_adl_swappable[2]>::value, true);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<test_ns::only_adl_swappable const[2]>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<test_ns::only_adl_swappable volatile[2]>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<test_ns::only_adl_swappable const volatile[2]>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<boost::type_traits_is_nothrow_swappable_test::swappable>::value, true);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<boost::type_traits_is_nothrow_swappable_test::swappable const>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<boost::type_traits_is_nothrow_swappable_test::swappable volatile>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<boost::type_traits_is_nothrow_swappable_test::swappable const volatile>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<boost::type_traits_is_nothrow_swappable_test::swappable[2]>::value, true);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<boost::type_traits_is_nothrow_swappable_test::swappable const[2]>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<boost::type_traits_is_nothrow_swappable_test::swappable volatile[2]>::value, false);
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BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_nothrow_swappable<boost::type_traits_is_nothrow_swappable_test::swappable const volatile[2]>::value, false);
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#endif // !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
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#endif
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TT_TEST_END
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