From 0db78d0a5e95572841a98754dca6c3513a3a334d Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
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<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 <jwakely@redhat.com>
+
+ 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 <polacek@redhat.com>
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<typename _U1, typename _U2> class __pair_base
{
#if __cplusplus >= 201103L
template<typename _T1, typename _T2> friend struct pair;
@@ -206,7 +206,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*/
template<typename _T1, typename _T2>
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
+// <http://www.gnu.org/licenses/>.
+
+#include <utility>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+ std::pair<std::pair<int, int>, 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<std::pair<empty, empty>, 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();
+}
--
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