| // Copyright (C) 2018-2022 Free Software Foundation, Inc. |
| // |
| // This file is part of the GNU ISO C++ Library. This library is free |
| // software; you can redistribute it and/or modify it under the |
| // terms of the GNU General Public License as published by the |
| // Free Software Foundation; either version 3, or (at your option) |
| // any later version. |
| |
| // This library is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // You should have received a copy of the GNU General Public License along |
| // with this library; see the file COPYING3. If not see |
| // <http://www.gnu.org/licenses/>. |
| |
| // { dg-options "-std=gnu++2a" } |
| // { dg-do compile { target c++2a } } |
| |
| #include <type_traits> |
| |
| template<typename T, typename U> struct expect_same; |
| template<typename T> struct expect_same<T, T> : std::true_type { }; |
| |
| template<typename T, typename U = std::decay_t<T>> |
| constexpr bool check() |
| { |
| using T2 = typename std::unwrap_ref_decay<T>::type; |
| static_assert(expect_same<T2, std::unwrap_ref_decay_t<T>>::value); |
| return expect_same<T2, U>::value; |
| } |
| |
| void |
| test01() |
| { |
| static_assert( check<int>() ); |
| static_assert( check<const int>() ); |
| static_assert( check<const int&>() ); |
| static_assert( check<const int*>() ); |
| static_assert( check<const int*&>() ); |
| |
| // reference_wrapper types (including cv and references) get unwrapped: |
| static_assert( check<std::reference_wrapper<int>, int&>() ); |
| static_assert( check<std::reference_wrapper<int>&, int&>() ); |
| static_assert( check<const std::reference_wrapper<int>, int&>() ); |
| static_assert( check<const std::reference_wrapper<int>&, int&>() ); |
| static_assert( check<std::reference_wrapper<const int>, const int&>() ); |
| static_assert( check<std::reference_wrapper<const int>&, const int&>() ); |
| static_assert( check<std::reference_wrapper<long>, long&>() ); |
| } |