This allows move-assignment for std::vector<T> when T is not
MoveAssignable but the allocator is moved or equal, as a QoI
extension. It also makes the code a bit cleaner and simpler, so I
plan to use the same pattern as I make the rest of the library meet
the allocator-aware container requirements.
PR libstdc++/52591
* include/bits/stl_vector.h (vector::operator=(vector&&)): Dispatch
to _M_move_assign depending on whether allocator is moved.
(vector::_M_move_assign): Add overloaded functions.
* testsuite/23_containers/vector/52591.cc: New.
* testsuite/23_containers/vector/requirements/dr438/assign_neg.cc:
Adjust dg-error line number.
*
testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc:
Likewise.
*
testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc:
Likewise.
* testsuite/23_containers/vector/requirements/dr438/insert_neg.cc:
Likewise.
Tested x86_64-linux, committed to trunk. After this has been on the
trunk for a while I plan to apply it to the 4.7 branch too.
commit e08d4fbd65667448fd93505acefc4828baff7a69
Author: Jonathan Wakely <jwakely....@gmail.com>
Date: Fri Mar 16 22:22:31 2012 +0000
PR libstdc++/52591
* include/bits/stl_vector.h (vector::operator=(vector&&)): Dispatch
to _M_move_assign depending on whether allocator is moved.
(vector::_M_move_assign): Add overloaded functions.
* testsuite/23_containers/vector/52591.cc: New.
* testsuite/23_containers/vector/requirements/dr438/assign_neg.cc:
Adjust dg-error line number.
*
testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc:
Likewise.
*
testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc:
Likewise.
* testsuite/23_containers/vector/requirements/dr438/insert_neg.cc:
Likewise.
diff --git a/libstdc++-v3/include/bits/stl_vector.h
b/libstdc++-v3/include/bits/stl_vector.h
index 239f8b9..31660d3 100644
--- a/libstdc++-v3/include/bits/stl_vector.h
+++ b/libstdc++-v3/include/bits/stl_vector.h
@@ -428,36 +428,18 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
* @brief %Vector move assignment operator.
* @param __x A %vector of identical element and allocator types.
*
- * The contents of @a __x are moved into this %vector (without copying).
+ * The contents of @a __x are moved into this %vector (without copying,
+ * if the allocators permit it).
* @a __x is a valid, but unspecified %vector.
*/
vector&
operator=(vector&& __x) noexcept(_Alloc_traits::_S_nothrow_move())
{
- if (_Alloc_traits::_S_propagate_on_move_assign())
- {
- // We're moving the rvalue's allocator so can move the data too.
- const vector __tmp(std::move(*this)); // discard existing data
- this->_M_impl._M_swap_data(__x._M_impl);
- std::__alloc_on_move(_M_get_Tp_allocator(),
- __x._M_get_Tp_allocator());
- }
- else if (_Alloc_traits::_S_always_equal()
- || __x._M_get_Tp_allocator() == this->_M_get_Tp_allocator())
- {
- // The rvalue's allocator can free our storage and vice versa,
- // so can swap the data storage after destroying our contents.
- this->clear();
- this->_M_impl._M_swap_data(__x._M_impl);
- }
- else
- {
- // The rvalue's allocator cannot be moved, or is not equal,
- // so we need to individually move each element.
- this->assign(std::__make_move_if_noexcept_iterator(__x.begin()),
- std::__make_move_if_noexcept_iterator(__x.end()));
- __x.clear();
- }
+ constexpr bool __move_storage =
+ _Alloc_traits::_S_propagate_on_move_assign()
+ || _Alloc_traits::_S_always_equal();
+ _M_move_assign(std::move(__x),
+ integral_constant<bool, __move_storage>());
return *this;
}
@@ -1363,6 +1345,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
std::_Destroy(__pos, this->_M_impl._M_finish, _M_get_Tp_allocator());
this->_M_impl._M_finish = __pos;
}
+
+#ifdef __GXX_EXPERIMENTAL_CXX0X__
+ private:
+ // Constant-time move assignment when source object's memory can be
+ // moved, either because the source's allocator will move too
+ // or because the allocators are equal.
+ void
+ _M_move_assign(vector&& __x, std::true_type) noexcept
+ {
+ const vector __tmp(std::move(*this));
+ this->_M_impl._M_swap_data(__x._M_impl);
+ if (_Alloc_traits::_S_propagate_on_move_assign())
+ std::__alloc_on_move(_M_get_Tp_allocator(),
+ __x._M_get_Tp_allocator());
+ }
+
+ // Do move assignment when it might not be possible to move source
+ // object's memory, resulting in a linear-time operation.
+ void
+ _M_move_assign(vector&& __x, std::false_type)
+ {
+ if (__x._M_get_Tp_allocator() == this->_M_get_Tp_allocator())
+ _M_move_assign(std::move(__x), std::true_type());
+ else
+ {
+ // The rvalue's allocator cannot be moved and is not equal,
+ // so we need to individually move each element.
+ this->assign(std::__make_move_if_noexcept_iterator(__x.begin()),
+ std::__make_move_if_noexcept_iterator(__x.end()));
+ __x.clear();
+ }
+ }
+#endif
};
diff --git a/libstdc++-v3/testsuite/23_containers/vector/52591.cc
b/libstdc++-v3/testsuite/23_containers/vector/52591.cc
new file mode 100644
index 0000000..c018c72
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/vector/52591.cc
@@ -0,0 +1,38 @@
+// Copyright (C) 2012 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 compile }
+// { dg-options "-std=gnu++0x" }
+
+// libstdc++/52591
+
+#include <vector>
+
+// As an extension we allow move-assignment of std::vector when the element
+// type is not MoveAssignable, as long as the allocator type propagates or
+// is known to always compare equal.
+
+struct C
+{
+ C& operator=(C&&) = delete;
+};
+
+void test01()
+{
+ std::vector<C> a;
+ a = std::vector<C>();
+}
diff --git
a/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/assign_neg.cc
b/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/assign_neg.cc
index 73de8ae..644750c 100644
---
a/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/assign_neg.cc
+++
b/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/assign_neg.cc
@@ -18,7 +18,7 @@
// <http://www.gnu.org/licenses/>.
// { dg-do compile }
-// { dg-error "no matching" "" { target *-*-* } 1251 }
+// { dg-error "no matching" "" { target *-*-* } 1233 }
#include <vector>
diff --git
a/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc
b/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc
index fa479c7..bbd4cfe 100644
---
a/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc
+++
b/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc
@@ -18,7 +18,7 @@
// <http://www.gnu.org/licenses/>.
// { dg-do compile }
-// { dg-error "no matching" "" { target *-*-* } 1181 }
+// { dg-error "no matching" "" { target *-*-* } 1163 }
#include <vector>
diff --git
a/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc
b/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc
index 231cace..d2282cc 100644
---
a/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc
+++
b/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc
@@ -18,7 +18,7 @@
// <http://www.gnu.org/licenses/>.
// { dg-do compile }
-// { dg-error "no matching" "" { target *-*-* } 1181 }
+// { dg-error "no matching" "" { target *-*-* } 1163 }
#include <vector>
#include <utility>
diff --git
a/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/insert_neg.cc
b/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/insert_neg.cc
index b8e18bb..d2cde66 100644
---
a/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/insert_neg.cc
+++
b/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/insert_neg.cc
@@ -18,7 +18,7 @@
// <http://www.gnu.org/licenses/>.
// { dg-do compile }
-// { dg-error "no matching" "" { target *-*-* } 1292 }
+// { dg-error "no matching" "" { target *-*-* } 1274 }
#include <vector>
