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// Copyright (C) 2018-2019 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 = T>
constexpr bool check()
{
using std::unwrap_reference;
using T2 = typename unwrap_reference<T>::type;
static_assert(expect_same<T2, typename unwrap_reference<T2>::type>::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 should get unwrapped:
static_assert( check<std::reference_wrapper<int>, int&>() );
static_assert( check<std::reference_wrapper<const int>, const int&>() );
static_assert( check<std::reference_wrapper<long>, long&>() );
// But not cv-qualified reference_wrapper types:
static_assert( check<const std::reference_wrapper<int>>() );
static_assert( check<volatile std::reference_wrapper<int>>() );
static_assert( check<const volatile std::reference_wrapper<int>>() );
// Or references to reference_wrapper types:
static_assert( check<std::reference_wrapper<int>&>() );
static_assert( check<std::reference_wrapper<int>&&>() );
static_assert( check<const std::reference_wrapper<int>&>() );
}
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