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 // test forward 13 14 #include <utility> 15 #include <type_traits> 16 #include <cassert> 17 18 #include "test_macros.h" 19 20 struct A 21 { 22 }; 23 24 A source() noexcept {return A();} 25 const A csource() noexcept {return A();} 26 27 28 constexpr bool test_constexpr_forward() { 29 #if TEST_STD_VER > 11 30 int x = 42; 31 const int cx = 101; 32 return std::forward<int&>(x) == 42 33 && std::forward<int>(x) == 42 34 && std::forward<const int&>(x) == 42 35 && std::forward<const int>(x) == 42 36 && std::forward<int&&>(x) == 42 37 && std::forward<const int&&>(x) == 42 38 && std::forward<const int&>(cx) == 101 39 && std::forward<const int>(cx) == 101; 40 #else 41 return true; 42 #endif 43 } 44 45 int main() 46 { 47 A a; 48 const A ca = A(); 49 50 ((void)a); // Prevent unused warning 51 ((void)ca); // Prevent unused warning 52 53 static_assert(std::is_same<decltype(std::forward<A&>(a)), A&>::value, ""); 54 static_assert(std::is_same<decltype(std::forward<A>(a)), A&&>::value, ""); 55 static_assert(std::is_same<decltype(std::forward<A>(source())), A&&>::value, ""); 56 static_assert(noexcept(std::forward<A&>(a)), ""); 57 static_assert(noexcept(std::forward<A>(a)), ""); 58 static_assert(noexcept(std::forward<A>(source())), ""); 59 60 static_assert(std::is_same<decltype(std::forward<const A&>(a)), const A&>::value, ""); 61 static_assert(std::is_same<decltype(std::forward<const A>(a)), const A&&>::value, ""); 62 static_assert(std::is_same<decltype(std::forward<const A>(source())), const A&&>::value, ""); 63 static_assert(noexcept(std::forward<const A&>(a)), ""); 64 static_assert(noexcept(std::forward<const A>(a)), ""); 65 static_assert(noexcept(std::forward<const A>(source())), ""); 66 67 static_assert(std::is_same<decltype(std::forward<const A&>(ca)), const A&>::value, ""); 68 static_assert(std::is_same<decltype(std::forward<const A>(ca)), const A&&>::value, ""); 69 static_assert(std::is_same<decltype(std::forward<const A>(csource())), const A&&>::value, ""); 70 static_assert(noexcept(std::forward<const A&>(ca)), ""); 71 static_assert(noexcept(std::forward<const A>(ca)), ""); 72 static_assert(noexcept(std::forward<const A>(csource())), ""); 73 74 #if TEST_STD_VER > 11 75 { 76 constexpr int i2 = std::forward<int>(42); 77 static_assert(std::forward<int>(42) == 42, ""); 78 static_assert(std::forward<const int&>(i2) == 42, ""); 79 static_assert(test_constexpr_forward(), ""); 80 } 81 #endif 82 #if TEST_STD_VER == 11 && defined(_LIBCPP_VERSION) 83 // Test that std::forward is constexpr in C++11. This is an extension 84 // provided by both libc++ and libstdc++. 85 { 86 constexpr int i2 = std::forward<int>(42); 87 static_assert(std::forward<int>(42) == 42, "" ); 88 static_assert(std::forward<const int&>(i2) == 42, ""); 89 } 90 #endif 91 } 92
