PR libstdc++/87822 fix layout change for nested std::pair
The introduction of the empty __pair_base base class for PR 86751 changed the layout of std::pair<std::pair<...>, ...>. The outer pair and its first member both have a base class of the same type, which cannot exist at the same address. This causes the first member to be at a non-zero offset. The solution is to make the base class depend on the template parameters, so that each pair type has a different base class type, which allows the base classes of the outer pair and its first member to have the same address. PR libstdc++/87822 * include/bits/stl_pair.h (__pair_base): Change to class template. (pair): Make base class type depend on template parameters. * testsuite/20_util/pair/87822.cc: New test. From-SVN: r265678
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2018-10-31 Jonathan Wakely <jwakely@redhat.com>
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PR libstdc++/87822
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* include/bits/stl_pair.h (__pair_base): Change to class template.
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(pair): Make base class type depend on template parameters.
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* testsuite/20_util/pair/87822.cc: New test.
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2018-10-30 Marek Polacek <polacek@redhat.com>
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2018-10-30 Marek Polacek <polacek@redhat.com>
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Implement P0892R2, explicit(bool).
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Implement P0892R2, explicit(bool).
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@ -187,7 +187,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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};
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};
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#endif // C++11
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#endif // C++11
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class __pair_base
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template<typename _U1, typename _U2> class __pair_base
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{
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{
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#if __cplusplus >= 201103L
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#if __cplusplus >= 201103L
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template<typename _T1, typename _T2> friend struct pair;
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template<typename _T1, typename _T2> friend struct pair;
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@ -206,7 +206,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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*/
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*/
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template<typename _T1, typename _T2>
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template<typename _T1, typename _T2>
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struct pair
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struct pair
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: private __pair_base
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: private __pair_base<_T1, _T2>
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{
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{
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typedef _T1 first_type; /// @c first_type is the first bound type
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typedef _T1 first_type; /// @c first_type is the first bound type
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typedef _T2 second_type; /// @c second_type is the second bound type
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typedef _T2 second_type; /// @c second_type is the second bound type
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// 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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#include <utility>
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#include <testsuite_hooks.h>
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void
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test01()
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{
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std::pair<std::pair<int, int>, int> p;
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#if __cplusplus >= 201103L
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static_assert(sizeof(p) == (3 * sizeof(int)), "PR libstdc++/87822");
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#endif
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VERIFY( (void*)&p == (void*)&p.first );
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}
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struct empty { };
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void
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test02()
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{
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std::pair<std::pair<empty, empty>, empty> p;
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#if __cplusplus >= 201103L
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static_assert(sizeof(p) == (3 * sizeof(empty)), "PR libstdc++/87822");
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#endif
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VERIFY( (void*)&p == (void*)&p.first );
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}
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int main()
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{
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test01();
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test02();
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}
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