commit a1cd60820fb1af7f3396ff4b28e0e1d3449bfacb Author: Jonathan Wakely Date: Tue Aug 25 17:10:36 2015 +0100 Only set std::enable_shared_from_this member once. * include/bits/shared_ptr.h (__enable_shared_from_this_helper): Use nullptr. * include/bits/shared_ptr_base.h (weak_ptr::_M_assign): Don't assign if ownership is already shared with a shared_ptr object. (__enable_shared_from_this_helper): Use nullptr. * testsuite/20_util/enable_shared_from_this/members/const.cc: New. * testsuite/20_util/enable_shared_from_this/members/reinit.cc: New. * testsuite/20_util/enable_shared_from_this/requirements/ explicit_instantiation.cc: Instantiate with const and incomplete types. diff --git a/libstdc++-v3/include/bits/shared_ptr.h b/libstdc++-v3/include/bits/shared_ptr.h index f96c078..2413b1b 100644 --- a/libstdc++-v3/include/bits/shared_ptr.h +++ b/libstdc++-v3/include/bits/shared_ptr.h @@ -588,7 +588,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION const enable_shared_from_this* __pe, const _Tp1* __px) noexcept { - if (__pe != 0) + if (__pe != nullptr) __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn); } diff --git a/libstdc++-v3/include/bits/shared_ptr_base.h b/libstdc++-v3/include/bits/shared_ptr_base.h index aec10fe..820edcb 100644 --- a/libstdc++-v3/include/bits/shared_ptr_base.h +++ b/libstdc++-v3/include/bits/shared_ptr_base.h @@ -1468,8 +1468,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION void _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept { - _M_ptr = __ptr; - _M_refcount = __refcount; + if (use_count() == 0) + { + _M_ptr = __ptr; + _M_refcount = __refcount; + } } template friend class __shared_ptr; @@ -1549,7 +1552,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION const __enable_shared_from_this* __pe, const _Tp1* __px) noexcept { - if (__pe != 0) + if (__pe != nullptr) __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn); } diff --git a/libstdc++-v3/testsuite/20_util/enable_shared_from_this/members/const.cc b/libstdc++-v3/testsuite/20_util/enable_shared_from_this/members/const.cc new file mode 100644 index 0000000..fdf39c7 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/enable_shared_from_this/members/const.cc @@ -0,0 +1,60 @@ +// Copyright (C) 2015 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 +// . + +// { dg-options "-std=gnu++11" } + +#include +#include + +template + bool + share_ownership(const std::shared_ptr& p1, const std::shared_ptr& p2) + { + return !p1.owner_before(p2) && !p2.owner_before(p1); + } + +void +test01() +{ + struct X : public std::enable_shared_from_this { }; + using CX = const X; + std::shared_ptr p(new X); + VERIFY( share_ownership(p->shared_from_this(), p) ); + p.reset(new CX); + VERIFY( share_ownership(p->shared_from_this(), p) ); + auto p2 = std::const_pointer_cast(p)->shared_from_this(); + VERIFY( share_ownership(p2, p) ); +} + +void +test02() +{ + struct X; + using CX = const X; + struct X : public std::enable_shared_from_this { }; + std::shared_ptr p(new X); + VERIFY( share_ownership(p->shared_from_this(), p) ); + p.reset(new CX); + VERIFY( share_ownership(p->shared_from_this(), p) ); +} + +int +main() +{ + test01(); + test02(); +} diff --git a/libstdc++-v3/testsuite/20_util/enable_shared_from_this/members/reinit.cc b/libstdc++-v3/testsuite/20_util/enable_shared_from_this/members/reinit.cc new file mode 100644 index 0000000..3740db8 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/enable_shared_from_this/members/reinit.cc @@ -0,0 +1,49 @@ +// Copyright (C) 2015 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 +// . + +// { dg-options "-std=gnu++11" } + +#include +#include + +struct X : public std::enable_shared_from_this { }; + +bool +share_ownership(const std::shared_ptr& p1, const std::shared_ptr& p2) +{ + return !p1.owner_before(p2) && !p2.owner_before(p1); +} + +void +test01() +{ + std::shared_ptr p1(new X); + VERIFY( share_ownership( p1->shared_from_this(), p1 ) ); + { + std::shared_ptr p2(p1.get(), [](X*){}); + // The weak_ptr member of the enable_shared_from_this base should not + // be reset by creating a second control block that owns the pointer. + VERIFY( share_ownership( p2->shared_from_this(), p1 ) ); + } + VERIFY( share_ownership( p1->shared_from_this(), p1 ) ); +} + +int +main() +{ + test01(); +} diff --git a/libstdc++-v3/testsuite/20_util/enable_shared_from_this/requirements/explicit_instantiation.cc b/libstdc++-v3/testsuite/20_util/enable_shared_from_this/requirements/explicit_instantiation.cc index 270ee84..94638e1 100644 --- a/libstdc++-v3/testsuite/20_util/enable_shared_from_this/requirements/explicit_instantiation.cc +++ b/libstdc++-v3/testsuite/20_util/enable_shared_from_this/requirements/explicit_instantiation.cc @@ -21,3 +21,8 @@ #include template class std::enable_shared_from_this; +template class std::enable_shared_from_this; + +class Incomplete; +template class std::enable_shared_from_this; +template class std::enable_shared_from_this;