1 //===----------------------------------------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // UNSUPPORTED: c++98, c++03 11 12 // <tuple> 13 14 // template <class... Types> class tuple; 15 16 // template <class ...UTypes> 17 // EXPLICIT(...) tuple(UTypes&&...) 18 19 // Check that the UTypes... ctor is properly disabled before evaluating any 20 // SFINAE when the tuple-like copy/move ctor should *clearly* be selected 21 // instead. This happens 'sizeof...(UTypes) == 1' and the first element of 22 // 'UTypes...' is an instance of the tuple itself. See PR23256. 23 24 #include <tuple> 25 #include <memory> 26 #include <type_traits> 27 28 29 struct UnconstrainedCtor { 30 int value_; 31 32 UnconstrainedCtor() : value_(0) {} 33 34 // Blows up when instantiated for any type other than int. Because the ctor 35 // is constexpr it is instantiated by 'is_constructible' and 'is_convertible' 36 // for Clang based compilers. GCC does not instantiate the ctor body 37 // but it does instantiate the noexcept specifier and it will blow up there. 38 template <typename T> 39 constexpr UnconstrainedCtor(T value) noexcept(noexcept(value_ = value)) 40 : value_(static_cast<int>(value)) 41 { 42 static_assert(std::is_same<int, T>::value, ""); 43 } 44 }; 45 46 struct ExplicitUnconstrainedCtor { 47 int value_; 48 49 ExplicitUnconstrainedCtor() : value_(0) {} 50 51 template <typename T> 52 constexpr explicit ExplicitUnconstrainedCtor(T value) 53 noexcept(noexcept(value_ = value)) 54 : value_(static_cast<int>(value)) 55 { 56 static_assert(std::is_same<int, T>::value, ""); 57 } 58 59 }; 60 61 int main() { 62 typedef UnconstrainedCtor A; 63 typedef ExplicitUnconstrainedCtor ExplicitA; 64 { 65 static_assert(std::is_copy_constructible<std::tuple<A>>::value, ""); 66 static_assert(std::is_move_constructible<std::tuple<A>>::value, ""); 67 static_assert(std::is_copy_constructible<std::tuple<ExplicitA>>::value, ""); 68 static_assert(std::is_move_constructible<std::tuple<ExplicitA>>::value, ""); 69 } 70 { 71 static_assert(std::is_constructible< 72 std::tuple<A>, 73 std::allocator_arg_t, std::allocator<void>, 74 std::tuple<A> const& 75 >::value, ""); 76 static_assert(std::is_constructible< 77 std::tuple<A>, 78 std::allocator_arg_t, std::allocator<void>, 79 std::tuple<A> && 80 >::value, ""); 81 static_assert(std::is_constructible< 82 std::tuple<ExplicitA>, 83 std::allocator_arg_t, std::allocator<void>, 84 std::tuple<ExplicitA> const& 85 >::value, ""); 86 static_assert(std::is_constructible< 87 std::tuple<ExplicitA>, 88 std::allocator_arg_t, std::allocator<void>, 89 std::tuple<ExplicitA> && 90 >::value, ""); 91 } 92 { 93 std::tuple<A&&> t(std::forward_as_tuple(A{})); 94 ((void)t); 95 std::tuple<ExplicitA&&> t2(std::forward_as_tuple(ExplicitA{})); 96 ((void)t2); 97 } 98 } 99
