1 // (C) Copyright Antony Polukhin 2013. 2 // 3 // Use, modification and distribution are subject to the Boost Software License, 4 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at 5 // http://www.boost.org/LICENSE_1_0.txt). 6 // 7 // See http://www.boost.org/libs/type_traits for most recent version including documentation. 8 9 #ifndef BOOST_TT_IS_COPY_CONSTRUCTIBLE_HPP_INCLUDED 10 #define BOOST_TT_IS_COPY_CONSTRUCTIBLE_HPP_INCLUDED 11 12 #include <boost/config.hpp> 13 #include <boost/detail/workaround.hpp> 14 15 #if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1800) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40900) 16 17 #include <boost/type_traits/is_constructible.hpp> 18 19 #if !BOOST_WORKAROUND(BOOST_MSVC, <= 1800) 20 21 namespace boost { 22 23 template <class T> struct is_copy_constructible : public boost::is_constructible<T, const T&>{}; 24 25 template <> struct is_copy_constructible<void> : public false_type{}; 26 template <> struct is_copy_constructible<void const> : public false_type{}; 27 template <> struct is_copy_constructible<void const volatile> : public false_type{}; 28 template <> struct is_copy_constructible<void volatile> : public false_type{}; 29 30 } // namespace boost 31 32 #else 33 // 34 // Special version for VC12 which has a problem when a base class (such as non_copyable) has a deleted 35 // copy constructor. In this case the compiler thinks there really is a copy-constructor and tries to 36 // instantiate the deleted member. std::is_copy_constructible has the same issue (or at least returns 37 // an incorrect value, which just defers the issue into the users code) as well. We can at least fix 38 // boost::non_copyable as a base class as a special case: 39 // 40 #include <boost/type_traits/is_noncopyable.hpp> 41 42 namespace boost { 43 44 namespace detail 45 { 46 47 template <class T, bool b> struct is_copy_constructible_imp : public boost::is_constructible<T, const T&>{}; 48 template <class T> struct is_copy_constructible_imp<T, true> : public false_type{}; 49 50 } 51 52 template <class T> struct is_copy_constructible : public detail::is_copy_constructible_imp<T, is_noncopyable<T>::value>{}; 53 54 template <> struct is_copy_constructible<void> : public false_type{}; 55 template <> struct is_copy_constructible<void const> : public false_type{}; 56 template <> struct is_copy_constructible<void const volatile> : public false_type{}; 57 template <> struct is_copy_constructible<void volatile> : public false_type{}; 58 59 } // namespace boost 60 61 #endif 62 63 #else 64 65 #include <boost/type_traits/detail/yes_no_type.hpp> 66 #include <boost/type_traits/is_noncopyable.hpp> 67 #include <boost/type_traits/add_reference.hpp> 68 #include <boost/type_traits/is_rvalue_reference.hpp> 69 #include <boost/type_traits/declval.hpp> 70 #include <boost/type_traits/is_array.hpp> 71 #include <boost/type_traits/declval.hpp> 72 73 #ifdef BOOST_MSVC 74 #pragma warning(push) 75 #pragma warning(disable:4181) 76 #endif 77 78 namespace boost { 79 80 namespace detail{ 81 82 template <bool DerivedFromNoncopyable, class T> 83 struct is_copy_constructible_impl2 { 84 85 // Intel compiler has problems with SFINAE for copy constructors and deleted functions: 86 // 87 // error: function *function_name* cannot be referenced -- it is a deleted function 88 // static boost::type_traits::yes_type test(T1&, decltype(T1(boost::declval<T1&>()))* = 0); 89 // ^ 90 // 91 // MSVC 12.0 (Visual 2013) has problems when the copy constructor has been deleted. See: 92 // https://connect.microsoft.com/VisualStudio/feedback/details/800328/std-is-copy-constructible-is-broken 93 #if !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS) && !defined(BOOST_INTEL_CXX_VERSION) && !(defined(BOOST_MSVC) && _MSC_VER == 1800) 94 95 #ifdef BOOST_NO_CXX11_DECLTYPE 96 template <class T1> 97 static boost::type_traits::yes_type test(const T1&, boost::mpl::int_<sizeof(T1(boost::declval<const T1&>()))>* = 0); 98 #else 99 template <class T1> 100 static boost::type_traits::yes_type test(const T1&, decltype(T1(boost::declval<const T1&>()))* = 0); 101 #endif 102 103 static boost::type_traits::no_type test(...); 104 #else 105 template <class T1> 106 static boost::type_traits::no_type test(const T1&, typename T1::boost_move_no_copy_constructor_or_assign* = 0); 107 static boost::type_traits::yes_type test(...); 108 #endif 109 110 // If you see errors like this: 111 // 112 // `'T::T(const T&)' is private` 113 // `boost/type_traits/is_copy_constructible.hpp:68:5: error: within this context` 114 // 115 // then you are trying to call that macro for a structure defined like that: 116 // 117 // struct T { 118 // ... 119 // private: 120 // T(const T &); 121 // ... 122 // }; 123 // 124 // To fix that you must modify your structure: 125 // 126 // // C++03 and C++11 version 127 // struct T: private boost::noncopyable { 128 // ... 129 // private: 130 // T(const T &); 131 // ... 132 // }; 133 // 134 // // C++11 version 135 // struct T { 136 // ... 137 // private: 138 // T(const T &) = delete; 139 // ... 140 // }; 141 BOOST_STATIC_CONSTANT(bool, value = ( 142 sizeof(test( 143 boost::declval<BOOST_DEDUCED_TYPENAME boost::add_reference<T const>::type>() 144 )) == sizeof(boost::type_traits::yes_type) 145 && 146 !boost::is_rvalue_reference<T>::value 147 && !boost::is_array<T>::value 148 )); 149 }; 150 151 template <class T> 152 struct is_copy_constructible_impl2<true, T> { 153 BOOST_STATIC_CONSTANT(bool, value = false); 154 }; 155 156 template <class T> 157 struct is_copy_constructible_impl { 158 159 BOOST_STATIC_CONSTANT(bool, value = ( 160 boost::detail::is_copy_constructible_impl2< 161 boost::is_noncopyable<T>::value, 162 T 163 >::value 164 )); 165 }; 166 167 } // namespace detail 168 169 template <class T> struct is_copy_constructible : public integral_constant<bool, ::boost::detail::is_copy_constructible_impl<T>::value>{}; 170 template <> struct is_copy_constructible<void> : public false_type{}; 171 #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS 172 template <> struct is_copy_constructible<void const> : public false_type{}; 173 template <> struct is_copy_constructible<void volatile> : public false_type{}; 174 template <> struct is_copy_constructible<void const volatile> : public false_type{}; 175 #endif 176 177 } // namespace boost 178 179 #ifdef BOOST_MSVC 180 #pragma warning(pop) 181 #endif 182 183 #endif 184 185 #endif // BOOST_TT_IS_COPY_CONSTRUCTIBLE_HPP_INCLUDED 186