From 0db78d0a5e95572841a98754dca6c3513a3a334d Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Wed, 31 Oct 2018 12:29:02 +0000 Subject: [PATCH] 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, ...>. 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 --- libstdc++-v3/ChangeLog | 7 +++ libstdc++-v3/include/bits/stl_pair.h | 4 +- libstdc++-v3/testsuite/20_util/pair/87822.cc | 47 ++++++++++++++++++++ 3 files changed, 56 insertions(+), 2 deletions(-) create mode 100644 libstdc++-v3/testsuite/20_util/pair/87822.cc diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index d9d4f0e64e0f..ac4df1ad515e 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,3 +1,10 @@ +2018-10-31 Jonathan Wakely + + 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. + 2018-10-30 Marek Polacek Implement P0892R2, explicit(bool). diff --git a/libstdc++-v3/include/bits/stl_pair.h b/libstdc++-v3/include/bits/stl_pair.h index ea8bd981559b..48af2b02ef97 100644 --- a/libstdc++-v3/include/bits/stl_pair.h +++ b/libstdc++-v3/include/bits/stl_pair.h @@ -187,7 +187,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION }; #endif // C++11 - class __pair_base + template class __pair_base { #if __cplusplus >= 201103L template friend struct pair; @@ -206,7 +206,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION */ template struct pair - : private __pair_base + : private __pair_base<_T1, _T2> { typedef _T1 first_type; /// @c first_type is the first bound type typedef _T2 second_type; /// @c second_type is the second bound type diff --git a/libstdc++-v3/testsuite/20_util/pair/87822.cc b/libstdc++-v3/testsuite/20_util/pair/87822.cc new file mode 100644 index 000000000000..cd099d6f9f9f --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/pair/87822.cc @@ -0,0 +1,47 @@ +// Copyright (C) 2018 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 +// . + +#include +#include + +void +test01() +{ + std::pair, int> p; +#if __cplusplus >= 201103L + static_assert(sizeof(p) == (3 * sizeof(int)), "PR libstdc++/87822"); +#endif + VERIFY( (void*)&p == (void*)&p.first ); +} + +struct empty { }; + +void +test02() +{ + std::pair, empty> p; +#if __cplusplus >= 201103L + static_assert(sizeof(p) == (3 * sizeof(empty)), "PR libstdc++/87822"); +#endif + VERIFY( (void*)&p == (void*)&p.first ); +} + +int main() +{ + test01(); + test02(); +} -- 2.39.2