1 // -*- C++ -*- 2 //===----------------------------------------------------------------------===// 3 // 4 // The LLVM Compiler Infrastructure 5 // 6 // This file is dual licensed under the MIT and the University of Illinois Open 7 // Source Licenses. See LICENSE.TXT for details. 8 // 9 //===----------------------------------------------------------------------===// 10 11 // UNSUPPORTED: c++98, c++03, c++11, c++14 12 13 // <variant> 14 15 // template <size_t I, class T> struct variant_alternative; // undefined 16 // template <size_t I, class T> struct variant_alternative<I, const T>; 17 // template <size_t I, class T> struct variant_alternative<I, volatile T>; 18 // template <size_t I, class T> struct variant_alternative<I, const volatile T>; 19 // template <size_t I, class T> 20 // using variant_alternative_t = typename variant_alternative<I, T>::type; 21 // 22 // template <size_t I, class... Types> 23 // struct variant_alternative<I, variant<Types...>>; 24 25 #include <memory> 26 #include <type_traits> 27 #include <variant> 28 29 #include "test_macros.h" 30 #include "variant_test_helpers.hpp" 31 32 template <class V, size_t I, class E> void test() { 33 static_assert( 34 std::is_same_v<typename std::variant_alternative<I, V>::type, E>, ""); 35 static_assert( 36 std::is_same_v<typename std::variant_alternative<I, const V>::type, 37 const E>, 38 ""); 39 static_assert( 40 std::is_same_v<typename std::variant_alternative<I, volatile V>::type, 41 volatile E>, 42 ""); 43 static_assert( 44 std::is_same_v< 45 typename std::variant_alternative<I, const volatile V>::type, 46 const volatile E>, 47 ""); 48 static_assert(std::is_same_v<std::variant_alternative_t<I, V>, E>, ""); 49 static_assert(std::is_same_v<std::variant_alternative_t<I, const V>, const E>, 50 ""); 51 static_assert( 52 std::is_same_v<std::variant_alternative_t<I, volatile V>, volatile E>, 53 ""); 54 static_assert(std::is_same_v<std::variant_alternative_t<I, const volatile V>, 55 const volatile E>, 56 ""); 57 } 58 59 int main() { 60 { 61 using V = std::variant<int, void *, const void *, long double>; 62 test<V, 0, int>(); 63 test<V, 1, void *>(); 64 test<V, 2, const void *>(); 65 test<V, 3, long double>(); 66 } 67 #if !defined(TEST_VARIANT_HAS_NO_REFERENCES) 68 { 69 using V = std::variant<int, int &, const int &, int &&, long double>; 70 test<V, 0, int>(); 71 test<V, 1, int &>(); 72 test<V, 2, const int &>(); 73 test<V, 3, int &&>(); 74 test<V, 4, long double>(); 75 } 76 #endif 77 } 78
