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* [gcc/devel/c++-modules] libstdc++: Make self-move well-defined for containers [PR 85828]
@ 2020-08-27 18:08 Nathan Sidwell
0 siblings, 0 replies; only message in thread
From: Nathan Sidwell @ 2020-08-27 18:08 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:c2fb0a1a2e7a0fb15cf3cf876f621902ccd273f0
commit c2fb0a1a2e7a0fb15cf3cf876f621902ccd273f0
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Wed Aug 12 20:36:00 2020 +0100
libstdc++: Make self-move well-defined for containers [PR 85828]
The C++ LWG recently confirmed that self-move assignment should not have
undefined behaviour for standard containers (see the proposed resolution
of LWG 2839). The result should be a valid but unspecified value, just
like other times when a container is moved from.
Our std::list, std::__cxx11::basic_string and unordered containers all
have bugs which result in undefined behaviour.
For std::list the problem is that we clear the previous contents using
_M_clear() instead of clear(). This means the _M_next, _M_prev and
_M_size members are not zeroed, and so after we "update" them (with
their existing values), we are left with dangling pointers and a
non-zero size, but no elements.
For the unordered containers the problem is similar. _Hashtable first
deallocates the existing contents, then takes ownership of the pointers
from the RHS object (which has just had its contents deallocated so the
pointers are dangling).
For std::basic_string it's a little more subtle. When the string is
local (i.e. fits in the SSO buffer) we use char_traits::copy to copy the
contents from this->data() to __rhs.data(). When &__rhs == this that
copy violates the precondition that the ranges don't overlap. We only
need to check for self-move for this case where it's local, because the
only other case that can be true for self-move is that it's non-local
but the allocators compare equal. In that case the data pointer is
neither deallocated nor leaked, so the result is well-defined.
This patch also makes a small optimization for std::deque move
assignment, to use the efficient move when is_always_equal is false, but
the allocators compare equal at runtime.
Finally, we need to remove all the Debug Mode checks which abort the
program when a self-move is detected, because it's not undefined to do
that.
Before PR 85828 can be closed we should also look into fixing
std::shuffle so it doesn't do any redundant self-swaps.
libstdc++-v3/ChangeLog:
PR libstdc++/85828
* include/bits/basic_string.h (operator=(basic_string&&)): Check
for self-move before copying with char_traits::copy.
* include/bits/hashtable.h (operator=(_Hashtable&&)): Check for
self-move.
* include/bits/stl_deque.h (_M_move_assign1(deque&&, false_type)):
Check for equal allocators.
* include/bits/stl_list.h (_M_move_assign(list&&, true_type)):
Call clear() instead of _M_clear().
* include/debug/formatter.h (__msg_self_move_assign): Change
comment.
* include/debug/macros.h (__glibcxx_check_self_move_assign):
(_GLIBCXX_DEBUG_VERIFY): Remove.
* include/debug/safe_container.h (operator=(_Safe_container&&)):
Remove assertion check for safe move and make it well-defined.
* include/debug/safe_iterator.h (operator=(_Safe_iterator&&)):
Remove assertion check for self-move.
* include/debug/safe_local_iterator.h
(operator=(_Safe_local_iterator&&)): Likewise.
* testsuite/21_strings/basic_string/cons/char/self_move.cc: New test.
* testsuite/23_containers/deque/cons/self_move.cc: New test.
* testsuite/23_containers/forward_list/cons/self_move.cc: New test.
* testsuite/23_containers/list/cons/self_move.cc: New test.
* testsuite/23_containers/set/cons/self_move.cc: New test.
* testsuite/23_containers/unordered_set/cons/self_move.cc: New test.
* testsuite/23_containers/vector/cons/self_move.cc: New test.
Diff:
---
libstdc++-v3/include/bits/basic_string.h | 13 ++++--
libstdc++-v3/include/bits/hashtable.h | 3 ++
libstdc++-v3/include/bits/stl_deque.h | 3 ++
libstdc++-v3/include/bits/stl_list.h | 2 +-
libstdc++-v3/include/debug/formatter.h | 2 +-
libstdc++-v3/include/debug/macros.h | 6 ---
libstdc++-v3/include/debug/safe_container.h | 9 +++-
libstdc++-v3/include/debug/safe_iterator.h | 6 +--
libstdc++-v3/include/debug/safe_local_iterator.h | 6 +--
.../21_strings/basic_string/cons/char/self_move.cc | 52 ++++++++++++++++++++++
.../23_containers/deque/cons/self_move.cc | 44 ++++++++++++++++++
.../23_containers/forward_list/cons/self_move.cc | 44 ++++++++++++++++++
.../testsuite/23_containers/list/cons/self_move.cc | 44 ++++++++++++++++++
.../testsuite/23_containers/set/cons/self_move.cc | 47 +++++++++++++++++++
.../23_containers/unordered_set/cons/self_move.cc | 50 +++++++++++++++++++++
.../23_containers/vector/cons/self_move.cc | 44 ++++++++++++++++++
16 files changed, 356 insertions(+), 19 deletions(-)
diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h
index e34b5c1fca3..a9fe09f2069 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -717,10 +717,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
if (__str._M_is_local())
{
- // We've always got room for a short string, just copy it.
- if (__str.size())
- this->_S_copy(_M_data(), __str._M_data(), __str.size());
- _M_set_length(__str.size());
+ // We've always got room for a short string, just copy it
+ // (unless this is a self-move, because that would violate the
+ // char_traits::copy precondition that the ranges don't overlap).
+ if (__builtin_expect(std::__addressof(__str) != this, true))
+ {
+ if (__str.size())
+ this->_S_copy(_M_data(), __str._M_data(), __str.size());
+ _M_set_length(__str.size());
+ }
}
else if (_Alloc_traits::_S_propagate_on_move_assign()
|| _Alloc_traits::_S_always_equal()
diff --git a/libstdc++-v3/include/bits/hashtable.h b/libstdc++-v3/include/bits/hashtable.h
index dc8ed2ee18c..7b772a475e3 100644
--- a/libstdc++-v3/include/bits/hashtable.h
+++ b/libstdc++-v3/include/bits/hashtable.h
@@ -1296,6 +1296,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_move_assign(_Hashtable&& __ht, true_type)
{
+ if (__builtin_expect(std::__addressof(__ht) == this, false))
+ return;
+
this->_M_deallocate_nodes(_M_begin());
_M_deallocate_buckets();
__hashtable_base::operator=(std::move(__ht));
diff --git a/libstdc++-v3/include/bits/stl_deque.h b/libstdc++-v3/include/bits/stl_deque.h
index 3959dd7899d..baebf7a343b 100644
--- a/libstdc++-v3/include/bits/stl_deque.h
+++ b/libstdc++-v3/include/bits/stl_deque.h
@@ -2156,6 +2156,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
void
_M_move_assign1(deque&& __x, /* always equal: */ false_type)
{
+ if (_M_get_Tp_allocator() == __x._M_get_Tp_allocator())
+ return _M_move_assign1(std::move(__x), true_type());
+
constexpr bool __move_storage =
_Alloc_traits::_S_propagate_on_move_assign();
_M_move_assign2(std::move(__x), __bool_constant<__move_storage>());
diff --git a/libstdc++-v3/include/bits/stl_list.h b/libstdc++-v3/include/bits/stl_list.h
index e7135e3e7ed..d63a96562e0 100644
--- a/libstdc++-v3/include/bits/stl_list.h
+++ b/libstdc++-v3/include/bits/stl_list.h
@@ -1947,7 +1947,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
void
_M_move_assign(list&& __x, true_type) noexcept
{
- this->_M_clear();
+ this->clear();
this->_M_move_nodes(std::move(__x));
std::__alloc_on_move(this->_M_get_Node_allocator(),
__x._M_get_Node_allocator());
diff --git a/libstdc++-v3/include/debug/formatter.h b/libstdc++-v3/include/debug/formatter.h
index bb9b3e5653a..c4283fe6047 100644
--- a/libstdc++-v3/include/debug/formatter.h
+++ b/libstdc++-v3/include/debug/formatter.h
@@ -143,7 +143,7 @@ namespace __gnu_debug
// unordered container local iterators
__msg_local_iter_compare_bad,
__msg_non_empty_range,
- // self move assign
+ // self move assign (no longer used)
__msg_self_move_assign,
// unordered container buckets
__msg_bucket_index_oob,
diff --git a/libstdc++-v3/include/debug/macros.h b/libstdc++-v3/include/debug/macros.h
index 73fb50d0cbd..ed606809a4d 100644
--- a/libstdc++-v3/include/debug/macros.h
+++ b/libstdc++-v3/include/debug/macros.h
@@ -447,12 +447,6 @@ _GLIBCXX_DEBUG_VERIFY(__gnu_debug::__check_partitioned_upper( \
._M_iterator(_Last, #_Last) \
._M_string(#_Pred))
-// Verify that the container is not self move assigned
-#define __glibcxx_check_self_move_assign(_Other) \
-_GLIBCXX_DEBUG_VERIFY(this != &_Other, \
- _M_message(__gnu_debug::__msg_self_move_assign) \
- ._M_sequence(*this, "this"))
-
// Verify that load factor is positive
#define __glibcxx_check_max_load_factor(_F) \
_GLIBCXX_DEBUG_VERIFY(_F > 0.0f, \
diff --git a/libstdc++-v3/include/debug/safe_container.h b/libstdc++-v3/include/debug/safe_container.h
index 36b3e017c19..2059eca9855 100644
--- a/libstdc++-v3/include/debug/safe_container.h
+++ b/libstdc++-v3/include/debug/safe_container.h
@@ -80,7 +80,14 @@ namespace __gnu_debug
_Safe_container&
operator=(_Safe_container&& __x) noexcept
{
- __glibcxx_check_self_move_assign(__x);
+ if (std::__addressof(__x) == this)
+ {
+ // Standard containers have a valid but unspecified value after
+ // self-move, so we invalidate all debug iterators even if the
+ // underlying container happens to preserve its contents.
+ this->_M_invalidate_all();
+ return *this;
+ }
if (_IsCxx11AllocatorAware)
{
diff --git a/libstdc++-v3/include/debug/safe_iterator.h b/libstdc++-v3/include/debug/safe_iterator.h
index 687b844fd75..84a9f1d526d 100644
--- a/libstdc++-v3/include/debug/safe_iterator.h
+++ b/libstdc++-v3/include/debug/safe_iterator.h
@@ -263,15 +263,15 @@ namespace __gnu_debug
_Safe_iterator&
operator=(_Safe_iterator&& __x) noexcept
{
- _GLIBCXX_DEBUG_VERIFY(this != &__x,
- _M_message(__msg_self_move_assign)
- ._M_iterator(*this, "this"));
_GLIBCXX_DEBUG_VERIFY(!__x._M_singular()
|| __x.base() == _Iterator(),
_M_message(__msg_copy_singular)
._M_iterator(*this, "this")
._M_iterator(__x, "other"));
+ if (std::__addressof(__x) == this)
+ return *this;
+
if (this->_M_sequence && this->_M_sequence == __x._M_sequence)
{
__gnu_cxx::__scoped_lock __l(this->_M_get_mutex());
diff --git a/libstdc++-v3/include/debug/safe_local_iterator.h b/libstdc++-v3/include/debug/safe_local_iterator.h
index d0abcf6da24..5b051d0ebf9 100644
--- a/libstdc++-v3/include/debug/safe_local_iterator.h
+++ b/libstdc++-v3/include/debug/safe_local_iterator.h
@@ -209,15 +209,15 @@ namespace __gnu_debug
_Safe_local_iterator&
operator=(_Safe_local_iterator&& __x) noexcept
{
- _GLIBCXX_DEBUG_VERIFY(this != &__x,
- _M_message(__msg_self_move_assign)
- ._M_iterator(*this, "this"));
_GLIBCXX_DEBUG_VERIFY(!__x._M_singular()
|| __x.base() == _Iterator(),
_M_message(__msg_copy_singular)
._M_iterator(*this, "this")
._M_iterator(__x, "other"));
+ if (std::__addressof(__x) == this)
+ return *this;
+
if (this->_M_sequence && this->_M_sequence == __x._M_sequence)
{
__gnu_cxx::__scoped_lock __l(this->_M_get_mutex());
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/self_move.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/self_move.cc
new file mode 100644
index 00000000000..456b03353c3
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/self_move.cc
@@ -0,0 +1,52 @@
+// Copyright (C) 2020 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/>.
+
+// { dg-do run { target c++11 } }
+
+#include <string>
+#include <debug/string>
+#include <testsuite_hooks.h>
+
+template<typename String>
+void
+test(const char* s)
+{
+ String s1 = s;
+ std::string s2 __attribute__((unused)) = s1.c_str();
+ s1 = std::move(s1);
+
+ String s3 __attribute__((unused)) = s1;
+ s1 = std::move(s1);
+
+ s1.begin(); // causes COW string to "leak"
+ s1 = std::move(s1);
+
+ String s4 __attribute__((unused)) = s1;
+ s1 = std::move(s1);
+
+ s1.reserve(2 * s1.capacity()); // causes SSO string to be on the heap
+ s1 = std::move(s1);
+}
+
+int
+main()
+{
+ test<std::string>("short");
+ test<std::string>("very, very, very, VERY long");
+ test<__gnu_debug::string>("short");
+ test<__gnu_debug::string>("very, very, very, VERY long");
+}
diff --git a/libstdc++-v3/testsuite/23_containers/deque/cons/self_move.cc b/libstdc++-v3/testsuite/23_containers/deque/cons/self_move.cc
new file mode 100644
index 00000000000..e05f43c572f
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/deque/cons/self_move.cc
@@ -0,0 +1,44 @@
+// Copyright (C) 2020 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/>.
+
+// { dg-do run { target c++11 } }
+
+#include <deque>
+#include <debug/deque>
+#include <testsuite_hooks.h>
+
+template<typename Container>
+void
+test(std::initializer_list<typename Container::value_type> vals)
+{
+ Container c{vals};
+ c = std::move(c);
+ VERIFY( c == c );
+
+ auto it = c.begin();
+ it = std::move(it);
+ VERIFY( it == c.begin() );
+}
+
+int
+main()
+{
+ test<std::deque<int>>({1, 2, 3});
+ test<std::deque<std::deque<int>>>({{1,2}, {3,4}, {5,6}, {7,8}});
+ test<__gnu_debug::deque<int>>({1, 2, 3});
+ test<__gnu_debug::deque<std::deque<int>>>({{1,2}, {3,4}});
+}
diff --git a/libstdc++-v3/testsuite/23_containers/forward_list/cons/self_move.cc b/libstdc++-v3/testsuite/23_containers/forward_list/cons/self_move.cc
new file mode 100644
index 00000000000..35525cab263
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/forward_list/cons/self_move.cc
@@ -0,0 +1,44 @@
+// Copyright (C) 2020 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/>.
+
+// { dg-do run { target c++11 } }
+
+#include <forward_list>
+#include <debug/forward_list>
+#include <testsuite_hooks.h>
+
+template<typename Container>
+void
+test(std::initializer_list<typename Container::value_type> vals)
+{
+ Container c{vals};
+ c = std::move(c);
+ VERIFY( c == c );
+
+ auto it = c.begin();
+ it = std::move(it);
+ VERIFY( it == c.begin() );
+}
+
+int
+main()
+{
+ test<std::forward_list<int>>({1, 2, 3});
+ test<std::forward_list<std::forward_list<int>>>({{1,2}, {3,4}, {5,6}, {7,8}});
+ test<__gnu_debug::forward_list<int>>({1, 2, 3});
+ test<__gnu_debug::forward_list<std::forward_list<int>>>({{1,2}, {3,4}});
+}
diff --git a/libstdc++-v3/testsuite/23_containers/list/cons/self_move.cc b/libstdc++-v3/testsuite/23_containers/list/cons/self_move.cc
new file mode 100644
index 00000000000..6ff6f1527e7
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/list/cons/self_move.cc
@@ -0,0 +1,44 @@
+// Copyright (C) 2020 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/>.
+
+// { dg-do run { target c++11 } }
+
+#include <list>
+#include <debug/list>
+#include <testsuite_hooks.h>
+
+template<typename Container>
+void
+test(std::initializer_list<typename Container::value_type> vals)
+{
+ Container c{vals};
+ c = std::move(c);
+ VERIFY( c == c );
+
+ auto it = c.begin();
+ it = std::move(it);
+ VERIFY( it == c.begin() );
+}
+
+int
+main()
+{
+ test<std::list<int>>({1, 2, 3});
+ test<std::list<std::list<int>>>({{1,2}, {3,4}, {5,6}, {7,8}});
+ test<__gnu_debug::list<int>>({1, 2, 3});
+ test<__gnu_debug::list<std::list<int>>>({{1,2}, {3,4}});
+}
diff --git a/libstdc++-v3/testsuite/23_containers/set/cons/self_move.cc b/libstdc++-v3/testsuite/23_containers/set/cons/self_move.cc
new file mode 100644
index 00000000000..9c226622ae6
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/set/cons/self_move.cc
@@ -0,0 +1,47 @@
+// Copyright (C) 2020 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/>.
+
+// { dg-do run { target c++11 } }
+
+#include <set>
+#include <debug/set>
+#include <string>
+#include <stdlib.h>
+#include <testsuite_hooks.h>
+
+template<typename Container>
+void
+test(std::initializer_list<typename Container::value_type> vals)
+{
+ Container c{vals};
+ c = std::move(c);
+ VERIFY( c == c );
+
+ auto it = c.begin();
+ it = std::move(it);
+ VERIFY( it == c.begin() );
+}
+
+int
+main()
+{
+ std::string s = "how long is a piece of SSO string?";
+ test<std::set<int>>({1, 2, 3});
+ test<std::set<std::string>>({s, s, s, s});
+ test<__gnu_debug::set<int>>({1, 2, 3});
+ test<__gnu_debug::set<std::string>>({s, s, s, s});
+}
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_set/cons/self_move.cc b/libstdc++-v3/testsuite/23_containers/unordered_set/cons/self_move.cc
new file mode 100644
index 00000000000..089f2c07b88
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/unordered_set/cons/self_move.cc
@@ -0,0 +1,50 @@
+// Copyright (C) 2020 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/>.
+
+// { dg-do run { target c++11 } }
+
+#include <unordered_set>
+#include <debug/unordered_set>
+#include <string>
+#include <stdlib.h>
+#include <testsuite_hooks.h>
+
+template<typename Container>
+void
+test(std::initializer_list<typename Container::value_type> vals)
+{
+ Container c{vals};
+ c = std::move(c);
+ VERIFY( c == c );
+
+ auto it = c.begin();
+ it = std::move(it);
+ VERIFY( it == c.begin() );
+
+ auto localit = c.begin(0);
+ localit = std::move(localit);
+}
+
+int
+main()
+{
+ std::string s = "how long is a piece of SSO string?";
+ test<std::unordered_set<int>>({1, 2, 3});
+ test<std::unordered_set<std::string>>({s, s, s, s});
+ test<__gnu_debug::unordered_set<int>>({1, 2, 3});
+ test<__gnu_debug::unordered_set<std::string>>({s, s, s, s});
+}
diff --git a/libstdc++-v3/testsuite/23_containers/vector/cons/self_move.cc b/libstdc++-v3/testsuite/23_containers/vector/cons/self_move.cc
new file mode 100644
index 00000000000..02159ee6293
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/vector/cons/self_move.cc
@@ -0,0 +1,44 @@
+// Copyright (C) 2020 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/>.
+
+// { dg-do run { target c++11 } }
+
+#include <vector>
+#include <debug/vector>
+#include <testsuite_hooks.h>
+
+template<typename Container>
+void
+test(std::initializer_list<typename Container::value_type> vals)
+{
+ Container c{vals};
+ c = std::move(c);
+ VERIFY( c == c );
+
+ auto it = c.begin();
+ it = std::move(it);
+ VERIFY( it == c.begin() );
+}
+
+int
+main()
+{
+ test<std::vector<int>>({1, 2, 3});
+ test<std::vector<std::vector<int>>>({{1,2}, {3,4}, {5,6}, {7,8}});
+ test<__gnu_debug::vector<int>>({1, 2, 3});
+ test<__gnu_debug::vector<std::vector<int>>>({{1,2}, {3,4}});
+}
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2020-08-27 18:08 [gcc/devel/c++-modules] libstdc++: Make self-move well-defined for containers [PR 85828] Nathan Sidwell
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