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