1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 // UNSUPPORTED: c++03, c++11, c++14 10 11 // type_traits 12 13 // is_swappable 14 15 #include <type_traits> 16 #include <utility> 17 #include <vector> 18 #include "test_macros.h" 19 20 namespace MyNS { 21 22 // Make the test types non-copyable so that generic std::swap is not valid. 23 struct A { 24 A(A const&) = delete; 25 A& operator=(A const&) = delete; 26 }; 27 28 struct B { 29 B(B const&) = delete; 30 B& operator=(B const&) = delete; 31 }; 32 33 struct C {}; 34 struct D {}; 35 36 void swap(A&, A&) {} 37 38 void swap(A&, B&) {} 39 void swap(B&, A&) {} 40 41 void swap(A&, C&) {} // missing swap(C, A) 42 void swap(D&, C&) {} 43 44 struct M { 45 M(M const&) = delete; 46 M& operator=(M const&) = delete; 47 }; 48 49 void swap(M&&, M&&) {} 50 51 struct DeletedSwap { 52 friend void swap(DeletedSwap&, DeletedSwap&) = delete; 53 }; 54 55 } // namespace MyNS 56 57 namespace MyNS2 { 58 59 struct AmbiguousSwap {}; 60 61 template <class T> 62 void swap(T&, T&) {} 63 64 } // namespace MyNS2 65 66 int main(int, char**) 67 { 68 using namespace MyNS; 69 { 70 // Test that is_swappable applies an lvalue reference to the type. 71 static_assert(std::is_swappable<A>::value, ""); 72 static_assert(std::is_swappable<A&>::value, ""); 73 static_assert(!std::is_swappable<M>::value, ""); 74 static_assert(!std::is_swappable<M&&>::value, ""); 75 } 76 static_assert(!std::is_swappable<B>::value, ""); 77 static_assert(std::is_swappable<C>::value, ""); 78 { 79 // test non-referencable types 80 static_assert(!std::is_swappable<void>::value, ""); 81 static_assert(!std::is_swappable<int() const>::value, ""); 82 static_assert(!std::is_swappable<int() &>::value, ""); 83 } 84 { 85 // test that a deleted swap is correctly handled. 86 static_assert(!std::is_swappable<DeletedSwap>::value, ""); 87 } 88 { 89 // test that a swap with ambiguous overloads is handled correctly. 90 static_assert(!std::is_swappable<MyNS2::AmbiguousSwap>::value, ""); 91 } 92 { 93 // test for presence of is_swappable_v 94 static_assert(std::is_swappable_v<int>, ""); 95 static_assert(!std::is_swappable_v<M>, ""); 96 } 97 98 return 0; 99 } 100