56 lines
1.8 KiB
C++
56 lines
1.8 KiB
C++
// Copyright (C) 2018-2020 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-do compile { target c++11 } }
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#include <functional>
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// LWG 2993. reference_wrapper<T> conversion from T&&
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static_assert(std::is_convertible<std::reference_wrapper<int>,
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std::reference_wrapper<const int>>::value,
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"LWG 2993 enables qualification conversions");
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// The comments below are taken from the issue discussion and describe the
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// behaviour before the resolution of LWG 2993. There should be no errors now.
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struct convertible_from_int { convertible_from_int(int) { } };
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void
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test01()
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{
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void meow(std::reference_wrapper<int>); //#1
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void meow(convertible_from_int); //#2
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// error, ambiguous; would unambiguously call #2 if #1 instead took int&
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meow(0);
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}
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void
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test02()
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{
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std::reference_wrapper<int> purr();
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// error, ambiguous: ICS exists from int prvalue to
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// reference_wrapper<int> and from reference_wrapper<int> to int
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auto x = true ? purr() : 0;
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// error: no member 'type' because the conditional
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// expression is ill-formed
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using t = typename std::common_type<std::reference_wrapper<int>, int>::type;
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}
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