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
source()24 A source() noexcept {return A();}
csource()25 const A csource() noexcept {return A();}
26
27
test_constexpr_forward()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
main()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