Marshall Clow | f60d092 | 2015-11-17 00:08:08 +0000 | [diff] [blame] | 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, c++11, c++14 |
| 11 | |
| 12 | // template <class T> constexpr add_const<T>& as_const(T& t) noexcept; // C++17 |
| 13 | // template <class T> add_const<T>& as_const(const T&&) = delete; // C++17 |
| 14 | |
| 15 | #include <utility> |
| 16 | #include <cassert> |
| 17 | |
| 18 | struct S {int i;}; |
| 19 | bool operator==(const S& x, const S& y) { return x.i == y.i; } |
| 20 | bool operator==(const volatile S& x, const volatile S& y) { return x.i == y.i; } |
| 21 | |
| 22 | template<typename T> |
| 23 | void test(T& t) |
| 24 | { |
| 25 | static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const (t))>::type>::value, ""); |
| 26 | static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const< T>(t))>::type>::value, ""); |
| 27 | static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const<const T>(t))>::type>::value, ""); |
| 28 | static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const<volatile T>(t))>::type>::value, ""); |
| 29 | static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const<const volatile T>(t))>::type>::value, ""); |
| 30 | |
| 31 | assert(std::as_const(t) == t); |
| 32 | assert(std::as_const< T>(t) == t); |
| 33 | assert(std::as_const<const T>(t) == t); |
| 34 | assert(std::as_const<volatile T>(t) == t); |
| 35 | assert(std::as_const<const volatile T>(t) == t); |
| 36 | } |
| 37 | |
| 38 | int main() |
| 39 | { |
| 40 | int i = 3; |
| 41 | double d = 4.0; |
| 42 | S s{2}; |
| 43 | test(i); |
| 44 | test(d); |
| 45 | test(s); |
| 46 | } |