39     template <typename First, typename Second>
41     struct __declspec(empty_bases) pair : detail::operators::adl<pair<First, Second>>
43     struct pair : detail::operators::adl<pair<First, Second>>
45                 , private detail::ebo<detail::pix<0>, First>
50             BOOST_HANA_TT_IS_CONSTRUCTIBLE(First, dummy...) &&
54             : detail::ebo<detail::pix<0>, First>()  in pair()
60             BOOST_HANA_TT_IS_CONSTRUCTIBLE(First, First const&, dummy...) &&
63         constexpr pair(First const& fst, Second const& snd)  in pair()
64             : detail::ebo<detail::pix<0>, First>(fst)  in pair()
69             BOOST_HANA_TT_IS_CONVERTIBLE(T&&, First) &&
73             : detail::ebo<detail::pix<0>, First>(static_cast<T&&>(t))  in pair()
80             BOOST_HANA_TT_IS_CONSTRUCTIBLE(First, T const&) &&
82             BOOST_HANA_TT_IS_CONVERTIBLE(T const&, First) &&
86             : detail::ebo<detail::pix<0>, First>(hana::first(other))  in pair()
91             BOOST_HANA_TT_IS_CONSTRUCTIBLE(First, T&&) &&
93             BOOST_HANA_TT_IS_CONVERTIBLE(T&&, First) &&
97             : detail::ebo<detail::pix<0>, First>(hana::first(static_cast<pair<T, U>&&>(other)))  in pair()
104             BOOST_HANA_TT_IS_ASSIGNABLE(First&, T const&) &&
114             BOOST_HANA_TT_IS_ASSIGNABLE(First&, T&&) &&
133     template <typename First, typename Second>
134     struct tag_of<pair<First, Second>> {
168         template <typename First, typename Second>
169         static constexpr decltype(auto) apply(hana::pair<First, Second>& p) {  in apply()
171                 static_cast<detail::ebo<detail::pix<0>, First>&>(p)  in apply()
174         template <typename First, typename Second>
175         static constexpr decltype(auto) apply(hana::pair<First, Second> const& p) {  in apply()
177                 static_cast<detail::ebo<detail::pix<0>, First> const&>(p)  in apply()
180         template <typename First, typename Second>
181         static constexpr decltype(auto) apply(hana::pair<First, Second>&& p) {  in apply()
183                 static_cast<detail::ebo<detail::pix<0>, First>&&>(p)  in apply()
190         template <typename First, typename Second>
191         static constexpr decltype(auto) apply(hana::pair<First, Second>& p) {  in apply()
196         template <typename First, typename Second>
197         static constexpr decltype(auto) apply(hana::pair<First, Second> const& p) {  in apply()
202         template <typename First, typename Second>
203         static constexpr decltype(auto) apply(hana::pair<First, Second>&& p) {  in apply()