boost/type_traits/is_copy_constructible.hpp

   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/type_traits/detail/yes_no_type.hpp>
  14 #include <boost/type_traits/is_base_and_derived.hpp>
  15 #include <boost/type_traits/add_reference.hpp>
  16 #include <boost/type_traits/is_rvalue_reference.hpp>
  17 #include <boost/utility/declval.hpp>
  18 #include <boost/noncopyable.hpp>
  19
  20 // should be the last #include
  21 #include <boost/type_traits/detail/bool_trait_def.hpp>
  22
  23 namespace boost {
  24
  25 namespace detail{
  26
  27 template <bool DerivedFromNoncopyable, class T>
  28 struct is_copy_constructible_impl2 {
  29
  30 // Intel compiler has problems with SFINAE for copy constructors and deleted functions:
  31 //
  32 // error: function *function_name* cannot be referenced -- it is a deleted function
  33 // static boost::type_traits::yes_type test(T1&, decltype(T1(boost::declval<T1&>()))* = 0);
  34 //                                                        ^
  35 //
  36 // MSVC 12.0 (Visual 2013) has problems when the copy constructor has been deleted. See:
  37 // https://connect.microsoft.com/VisualStudio/feedback/details/800328/std-is-copy-constructible-is-broken
  38 #if !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS) && !defined(BOOST_INTEL_CXX_VERSION) && !(defined(BOOST_MSVC) && _MSC_VER == 1800)
  39
  40 #ifdef BOOST_NO_CXX11_DECLTYPE
  41     template <class T1>
  42     static boost::type_traits::yes_type test(T1&, boost::mpl::int_<sizeof(T1(boost::declval<T1&>()))>* = 0);
  43 #else
  44     template <class T1>
  45     static boost::type_traits::yes_type test(T1&, decltype(T1(boost::declval<T1&>()))* = 0);
  46 #endif
  47
  48     static boost::type_traits::no_type test(...);
  49 #else
  50     template <class T1>
  51     static boost::type_traits::no_type test(T1&, typename T1::boost_move_no_copy_constructor_or_assign* = 0);
  52     static boost::type_traits::yes_type test(...);
  53 #endif
  54
  55     // If you see errors like this:
  56     //
  57     //      `'T::T(const T&)' is private`
  58     //      `boost/type_traits/is_copy_constructible.hpp:68:5: error: within this context`
  59     //
  60     // then you are trying to call that macro for a structure defined like that:
  61     //
  62     //      struct T {
  63     //          ...
  64     //      private:
  65     //          T(const T &);
  66     //          ...
  67     //      };
  68     //
  69     // To fix that you must modify your structure:
  70     //
  71     //      // C++03 and C++11 version
  72     //      struct T: private boost::noncopyable {
  73     //          ...
  74     //      private:
  75     //          T(const T &);
  76     //          ...
  77     //      };
  78     //
  79     //      // C++11 version
  80     //      struct T {
  81     //          ...
  82     //      private:
  83     //          T(const T &) = delete;
  84     //          ...
  85     //      };
  86     BOOST_STATIC_CONSTANT(bool, value = (
  87             sizeof(test(
  88                 boost::declval<BOOST_DEDUCED_TYPENAME boost::add_reference<T>::type>()
  89             )) == sizeof(boost::type_traits::yes_type)
  90         ||
  91             boost::is_rvalue_reference<T>::value
  92     ));
  93 };
  94
  95 template <class T>
  96 struct is_copy_constructible_impl2<true, T> {
  97     BOOST_STATIC_CONSTANT(bool, value = false);
  98 };
  99
 100 template <class T>
 101 struct is_copy_constructible_impl {
 102
 103     BOOST_STATIC_CONSTANT(bool, value = (
 104         boost::detail::is_copy_constructible_impl2<
 105             boost::is_base_and_derived<boost::noncopyable, T>::value,
 106             T
 107         >::value
 108     ));
 109 };
 110
 111 } // namespace detail
 112
 113 BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_copy_constructible,T,::boost::detail::is_copy_constructible_impl<T>::value)
 114 BOOST_TT_AUX_BOOL_TRAIT_SPEC1(is_copy_constructible,void,false)
 115 #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
 116 BOOST_TT_AUX_BOOL_TRAIT_SPEC1(is_copy_constructible,void const,false)
 117 BOOST_TT_AUX_BOOL_TRAIT_SPEC1(is_copy_constructible,void const volatile,false)
 118 BOOST_TT_AUX_BOOL_TRAIT_SPEC1(is_copy_constructible,void volatile,false)
 119 #endif
 120
 121 } // namespace boost
 122
 123 #include <boost/type_traits/detail/bool_trait_undef.hpp>
 124
 125 #endif // BOOST_TT_IS_COPY_CONSTRUCTIBLE_HPP_INCLUDED