boost/type_traits/is_copy_constructible.hpp
// (C) Copyright Antony Polukhin 2013. // // 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/type_traits for most recent version including documentation. #ifndef BOOST_TT_IS_COPY_CONSTRUCTIBLE_HPP_INCLUDED #define BOOST_TT_IS_COPY_CONSTRUCTIBLE_HPP_INCLUDED #include <boost/config.hpp> #include <boost/detail/workaround.hpp> #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1800) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40900) #include <boost/type_traits/is_constructible.hpp> #if !BOOST_WORKAROUND(BOOST_MSVC, <= 1800) namespace boost { template <class T> struct is_copy_constructible : public boost::is_constructible<T, const T&>{}; template <> struct is_copy_constructible<void> : public false_type{}; template <> struct is_copy_constructible<void const> : public false_type{}; template <> struct is_copy_constructible<void const volatile> : public false_type{}; template <> struct is_copy_constructible<void volatile> : public false_type{}; } // namespace boost #else // // Special version for VC12 which has a problem when a base class (such as non_copyable) has a deleted // copy constructor. In this case the compiler thinks there really is a copy-constructor and tries to // instantiate the deleted member. std::is_copy_constructible has the same issue (or at least returns // an incorrect value, which just defers the issue into the users code) as well. We can at least fix // boost::non_copyable as a base class as a special case: // #include <boost/type_traits/is_noncopyable.hpp> namespace boost { namespace detail { template <class T, bool b> struct is_copy_constructible_imp : public boost::is_constructible<T, const T&>{}; template <class T> struct is_copy_constructible_imp<T, true> : public false_type{}; } template <class T> struct is_copy_constructible : public detail::is_copy_constructible_imp<T, is_noncopyable<T>::value>{}; template <> struct is_copy_constructible<void> : public false_type{}; template <> struct is_copy_constructible<void const> : public false_type{}; template <> struct is_copy_constructible<void const volatile> : public false_type{}; template <> struct is_copy_constructible<void volatile> : public false_type{}; } // namespace boost #endif #else #include <boost/type_traits/detail/yes_no_type.hpp> #include <boost/type_traits/is_noncopyable.hpp> #include <boost/type_traits/add_reference.hpp> #include <boost/type_traits/is_rvalue_reference.hpp> #include <boost/type_traits/declval.hpp> #include <boost/type_traits/is_array.hpp> #include <boost/type_traits/declval.hpp> #ifdef BOOST_MSVC #pragma warning(push) #pragma warning(disable:4181) #endif namespace boost { namespace detail{ template <bool DerivedFromNoncopyable, class T> struct is_copy_constructible_impl2 { // Intel compiler has problems with SFINAE for copy constructors and deleted functions: // // error: function *function_name* cannot be referenced -- it is a deleted function // static boost::type_traits::yes_type test(T1&, decltype(T1(boost::declval<T1&>()))* = 0); // ^ // // MSVC 12.0 (Visual 2013) has problems when the copy constructor has been deleted. See: // https://connect.microsoft.com/VisualStudio/feedback/details/800328/std-is-copy-constructible-is-broken #if !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS) && !defined(BOOST_INTEL_CXX_VERSION) && !(defined(BOOST_MSVC) && _MSC_VER == 1800) #ifdef BOOST_NO_CXX11_DECLTYPE template <class T1> static boost::type_traits::yes_type test(const T1&, boost::mpl::int_<sizeof(T1(boost::declval<const T1&>()))>* = 0); #else template <class T1> static boost::type_traits::yes_type test(const T1&, decltype(T1(boost::declval<const T1&>()))* = 0); #endif static boost::type_traits::no_type test(...); #else template <class T1> static boost::type_traits::no_type test(const T1&, typename T1::boost_move_no_copy_constructor_or_assign* = 0); static boost::type_traits::yes_type test(...); #endif // If you see errors like this: // // `'T::T(const T&)' is private` // `boost/type_traits/is_copy_constructible.hpp:68:5: error: within this context` // // then you are trying to call that macro for a structure defined like that: // // struct T { // ... // private: // T(const T &); // ... // }; // // To fix that you must modify your structure: // // // C++03 and C++11 version // struct T: private boost::noncopyable { // ... // private: // T(const T &); // ... // }; // // // C++11 version // struct T { // ... // private: // T(const T &) = delete; // ... // }; BOOST_STATIC_CONSTANT(bool, value = ( sizeof(test( boost::declval<BOOST_DEDUCED_TYPENAME boost::add_reference<T const>::type>() )) == sizeof(boost::type_traits::yes_type) && !boost::is_rvalue_reference<T>::value && !boost::is_array<T>::value )); }; template <class T> struct is_copy_constructible_impl2<true, T> { BOOST_STATIC_CONSTANT(bool, value = false); }; template <class T> struct is_copy_constructible_impl { BOOST_STATIC_CONSTANT(bool, value = ( boost::detail::is_copy_constructible_impl2< boost::is_noncopyable<T>::value, T >::value )); }; } // namespace detail template <class T> struct is_copy_constructible : public integral_constant<bool, ::boost::detail::is_copy_constructible_impl<T>::value>{}; template <> struct is_copy_constructible<void> : public false_type{}; #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS template <> struct is_copy_constructible<void const> : public false_type{}; template <> struct is_copy_constructible<void volatile> : public false_type{}; template <> struct is_copy_constructible<void const volatile> : public false_type{}; #endif } // namespace boost #ifdef BOOST_MSVC #pragma warning(pop) #endif #endif #endif // BOOST_TT_IS_COPY_CONSTRUCTIBLE_HPP_INCLUDED