This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [v3 PATCH] basic_string spurious use of a default constructible allocator - LWG2788
- From: Jonathan Wakely <jwakely at redhat dot com>
- To: Nina Dinka Ranns <dinka dot ranns at gmail dot com>
- Cc: gcc-patches List <gcc-patches at gcc dot gnu dot org>, libstdc++ <libstdc++ at gcc dot gnu dot org>
- Date: Thu, 30 May 2019 20:48:47 +0100
- Subject: Re: [v3 PATCH] basic_string spurious use of a default constructible allocator - LWG2788
- References: <CAAcHv8euPnFShaO6dF308m91t2pxszfB2UT2rDijMNEhn6cVEw@mail.gmail.com>
On 27/05/19 11:53 +0100, Nina Dinka Ranns wrote:
Tested on Linux x86_64
basic_string spurious use of a default constructible allocator - LWG2788
2019-05-27 Nina Dinka Ranns <dinka.ranns@gmail.com>
basic_string spurious use of a default constructible allocator - LWG2788
* bits/basic_string.tcc:
(_M_replace_dispatch()): string temporary now constructed with
the current allocator
* testsuite/21_strings/basic_string/allocator/char/lwg2788.cc: New
* testsuite/21_strings/basic_string/allocator/wchar_t/lwg2788.cc: New
Thanks!
Index: libstdc++-v3/include/bits/basic_string.tcc
===================================================================
--- libstdc++-v3/include/bits/basic_string.tcc (revision 271509)
+++ libstdc++-v3/include/bits/basic_string.tcc (working copy)
@@ -381,7 +381,9 @@
_InputIterator __k1, _InputIterator __k2,
std::__false_type)
{
- const basic_string __s(__k1, __k2);
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 2788. unintentionally require a default constructible allocator
I've fixed the indentation of this comment.
+ const basic_string __s(__k1, __k2, this->get_allocator());
const size_type __n1 = __i2 - __i1;
return _M_replace(__i1 - begin(), __n1, __s._M_data(),
__s.size());
Index: libstdc++-v3/testsuite/20_util/nonesuch/nonesuch.cc
===================================================================
--- libstdc++-v3/testsuite/20_util/nonesuch/nonesuch.cc (revision 271509)
+++ libstdc++-v3/testsuite/20_util/nonesuch/nonesuch.cc (nonexistent)
And dropped this part of the patch which spuriously removed an
unrelated file.
Tested powerpc64le-linux with both string ABIs.
The version I've committed is attached.
commit a0ee1818604eb6998e9cc26005ba754021a3f067
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu May 30 17:45:38 2019 +0100
LWG2788 basic_string spurious use of a default constructible allocator
This only change the cxx11 basic_string, because COW strings don't
correctly propagate allocators anyway.
2019-05-30 Nina Dinka Ranns <dinka.ranns@gmail.com>
LWG2788 basic_string spurious use of a default constructible allocator
* include/bits/basic_string.tcc [_GLIBCXX_USE_CXX11_ABI]
(basic_string::_M_replace_dispatch): Construct temporary string with
the current allocator.
* testsuite/21_strings/basic_string/allocator/char/lwg2788.cc: New.
* testsuite/21_strings/basic_string/allocator/wchar_t/lwg2788.cc: New.
diff --git a/libstdc++-v3/include/bits/basic_string.tcc b/libstdc++-v3/include/bits/basic_string.tcc
index e2315cb1467..ab986a6c827 100644
--- a/libstdc++-v3/include/bits/basic_string.tcc
+++ b/libstdc++-v3/include/bits/basic_string.tcc
@@ -381,7 +381,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_InputIterator __k1, _InputIterator __k2,
std::__false_type)
{
- const basic_string __s(__k1, __k2);
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 2788. unintentionally require a default constructible allocator
+ const basic_string __s(__k1, __k2, this->get_allocator());
const size_type __n1 = __i2 - __i1;
return _M_replace(__i1 - begin(), __n1, __s._M_data(),
__s.size());
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/allocator/char/lwg2788.cc b/libstdc++-v3/testsuite/21_strings/basic_string/allocator/char/lwg2788.cc
new file mode 100644
index 00000000000..36dd414e887
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/allocator/char/lwg2788.cc
@@ -0,0 +1,85 @@
+// { dg-do run { target c++11 } }
+// { dg-require-effective-target cxx11-abi }
+
+// 2019-05-27 Nina Dinka Ranns <dinka.ranns@gmail.com>
+//
+// Copyright (C) 2015-2019 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 <string>
+#include <testsuite_hooks.h>
+
+using C = char;
+using traits = std::char_traits<C>;
+int constructCount = 0;
+
+static void resetCounter()
+{
+ constructCount = 0;
+}
+
+template <class Tp>
+struct TestAllocator
+{
+ typedef Tp value_type;
+ using size_type = unsigned;
+
+ TestAllocator() noexcept { constructCount++; }
+
+ template <class T>
+ TestAllocator(const TestAllocator<T>&) {}
+
+ Tp *allocate(std::size_t n)
+ { return std::allocator<Tp>().allocate(n); }
+
+ void deallocate(Tp *p, std::size_t n)
+ { std::allocator<Tp>().deallocate(p, n); }
+
+};
+
+template <class T, class U>
+bool operator==(const TestAllocator<T>&, const TestAllocator<U>&)
+{ return true; }
+template <class T, class U>
+bool operator!=(const TestAllocator<T>&, const TestAllocator<U>&)
+{ return false; }
+
+void test01()
+{
+ typedef TestAllocator<C> alloc_type;
+ typedef std::basic_string<C, traits, alloc_type> test_type;
+ test_type v1{alloc_type()};
+ std::string v2{"some_content"};
+
+ resetCounter();
+ v1.assign(v2.begin(),v2.end());
+ VERIFY( constructCount == 0);
+
+ v1.append(v2.begin(),v2.end());
+ VERIFY( constructCount == 0);
+
+ v1.insert(v1.begin(),v1.begin(),v1.end());
+ VERIFY( constructCount == 0);
+
+ v1.replace(v1.begin(),v1.end(),v1.begin(),v1.end());
+ VERIFY( constructCount == 0);
+}
+int main()
+{
+ test01();
+ return 0;
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/allocator/wchar_t/lwg2788.cc b/libstdc++-v3/testsuite/21_strings/basic_string/allocator/wchar_t/lwg2788.cc
new file mode 100644
index 00000000000..8e26dd7d4a9
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/allocator/wchar_t/lwg2788.cc
@@ -0,0 +1,85 @@
+// { dg-do run { target c++11 } }
+// { dg-require-effective-target cxx11-abi }
+
+// 2019-05-27 Nina Dinka Ranns <dinka.ranns@gmail.com>
+//
+// Copyright (C) 2015-2019 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 <string>
+#include <testsuite_hooks.h>
+
+using C = wchar_t;
+using traits = std::char_traits<C>;
+int constructCount = 0;
+
+static void resetCounter()
+{
+ constructCount = 0;
+}
+
+template <class Tp>
+struct TestAllocator
+{
+ typedef Tp value_type;
+ using size_type = unsigned;
+
+ TestAllocator() noexcept { constructCount++; }
+
+ template <class T>
+ TestAllocator(const TestAllocator<T>&) {}
+
+ Tp *allocate(std::size_t n)
+ { return std::allocator<Tp>().allocate(n); }
+
+ void deallocate(Tp *p, std::size_t n)
+ { std::allocator<Tp>().deallocate(p, n); }
+
+};
+
+template <class T, class U>
+bool operator==(const TestAllocator<T>&, const TestAllocator<U>&)
+{ return true; }
+template <class T, class U>
+bool operator!=(const TestAllocator<T>&, const TestAllocator<U>&)
+{ return false; }
+
+void test01()
+{
+ typedef TestAllocator<C> alloc_type;
+ typedef std::basic_string<C, traits, alloc_type> test_type;
+ test_type v1{alloc_type()};
+ std::wstring v2{L"some_content"};
+
+ resetCounter();
+ v1.assign(v2.begin(),v2.end());
+ VERIFY( constructCount == 0);
+
+ v1.append(v2.begin(),v2.end());
+ VERIFY( constructCount == 0);
+
+ v1.insert(v1.begin(),v1.begin(),v1.end());
+ VERIFY( constructCount == 0);
+
+ v1.replace(v1.begin(),v1.end(),v1.begin(),v1.end());
+ VERIFY( constructCount == 0);
+}
+int main()
+{
+ test01();
+ return 0;
+}