commit 8aee705324a8a5463a89a6cab0d77c20ae99ee41
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon Dec 12 15:25:14 2016 +0000
Enable experimental::enable_shared_from_this explicitly
Backport from mainline
2016-10-19 Jonathan Wakely <jwakely@redhat.com>
* include/experimental/bits/shared_ptr.h (experimental::shared_ptr):
Change relevant constructors to call _M_enable_shared_from_this_with.
(experimental::shared_ptr::__efst_base_t)
(experimental::shared_ptr::__has_efst_base): Helpers to detect
accessible and unambiguous enable_shared_from_this bases.
(experimental::shared_ptr::_M_enable_shared_from_this_with): Define.
(experimental::__enable_shared_from_this_helper): Remove overload for
std::experimental::enable_shared_from_this.
(experimental::__expt_enable_shared_from_this_base): Define friend
function to select a std::experimental::enable_shared_from_this base.
* testsuite/experimental/memory/shared_ptr/cons/
enable_shared_from_this.cc: New test.
* testsuite/experimental/memory/shared_ptr/cons/unique_ptr_ctor.cc:
Adjust expected behaviour for shared_ptr<A[]>.
@@ -259,7 +259,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// {
// void* __p = _M_refcount._M_get_deleter(typeid(__tag));
// _M_ptr = static_cast<_Tp*>(__p);
- // __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr);
// }
// __weak_ptr::lock()
@@ -557,7 +556,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// {
// void* __p = _M_refcount._M_get_deleter(typeid(__tag));
// _M_ptr = static_cast<_Tp*>(__p);
- // __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr);
// }
// __weak_ptr::lock()
@@ -740,16 +738,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp1, typename = _SafeConv<_Tp1>>
explicit
- shared_ptr(_Tp1* __p) : _Base_type(__p) { }
+ shared_ptr(_Tp1* __p) : _Base_type(__p)
+ { _M_enable_shared_from_this_with(__p); }
template<typename _Tp1, typename _Deleter, typename = _SafeConv<_Tp1>>
shared_ptr(_Tp1* __p, _Deleter __d)
- : _Base_type(__p, __d) { }
+ : _Base_type(__p, __d)
+ { _M_enable_shared_from_this_with(__p); }
template<typename _Tp1, typename _Deleter, typename _Alloc,
typename = _SafeConv<_Tp1>>
shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a)
- : _Base_type(__p, __d, __a) { }
+ : _Base_type(__p, __d, __a)
+ { _M_enable_shared_from_this_with(__p); }
template<typename _Deleter>
shared_ptr(nullptr_t __p, _Deleter __d)
@@ -785,13 +786,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#if _GLIBCXX_USE_DEPRECATED
template<typename _Tp1, typename = _Compatible<_Tp1>>
shared_ptr(std::auto_ptr<_Tp1>&& __r)
- : _Base_type(std::move(__r)) { }
+ : _Base_type(std::move(__r))
+ { _M_enable_shared_from_this_with(static_cast<_Tp1*>(this->get())); }
#endif
template<typename _Tp1, typename _Del,
typename = _UniqCompatible<_Tp1, _Del>>
shared_ptr(unique_ptr<_Tp1, _Del>&& __r)
- : _Base_type(std::move(__r)) { }
+ : _Base_type(std::move(__r))
+ {
+ // XXX assume conversion from __r.get() to this->get() to __elem_t*
+ // is a round trip, which might not be true in all cases.
+ using __elem_t = typename unique_ptr<_Tp1, _Del>::element_type;
+ _M_enable_shared_from_this_with(static_cast<__elem_t*>(this->get()));
+ }
constexpr shared_ptr(nullptr_t __p)
: _Base_type(__p) { }
@@ -853,7 +861,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
_Args&&... __args)
: _Base_type(__tag, __a, std::forward<_Args>(__args)...)
- { }
+ { _M_enable_shared_from_this_with(this->get()); }
template<typename _Tp1, typename _Alloc, typename... _Args>
friend shared_ptr<_Tp1>
@@ -863,6 +871,35 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
: _Base_type(__r, std::nothrow) { }
friend class weak_ptr<_Tp>;
+
+ template<typename _Yp>
+ using __esft_base_t =
+ decltype(__expt_enable_shared_from_this_base(std::declval<_Yp*>()));
+
+ // Detect an accessible and unambiguous enable_shared_from_this base.
+ template<typename _Yp, typename = void>
+ struct __has_esft_base
+ : false_type { };
+
+ template<typename _Yp>
+ struct __has_esft_base<_Yp, __void_t<__esft_base_t<_Yp>>>
+ : __bool_constant<!is_array_v<_Tp>> { }; // ignore base for arrays
+
+ template<typename _Yp>
+ typename enable_if<__has_esft_base<_Yp>::value>::type
+ _M_enable_shared_from_this_with(const _Yp* __p) noexcept
+ {
+ if (auto __base = __expt_enable_shared_from_this_base(__p))
+ {
+ __base->_M_weak_this
+ = shared_ptr<_Yp>(*this, const_cast<_Yp*>(__p));
+ }
+ }
+
+ template<typename _Yp>
+ typename enable_if<!__has_esft_base<_Yp>::value>::type
+ _M_enable_shared_from_this_with(const _Yp*) noexcept
+ { }
};
// C++14 ??20.8.2.2.7 //DOING
@@ -1258,15 +1295,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept
{ _M_weak_this._M_assign(__p, __n); }
- template<typename _Tp1>
- friend void
- __enable_shared_from_this_helper(const __shared_count<>& __pn,
- const enable_shared_from_this* __pe,
- const _Tp1* __px) noexcept
- {
- if(__pe != 0)
- __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
- }
+ // Found by ADL when this is an associated class.
+ friend const enable_shared_from_this*
+ __expt_enable_shared_from_this_base(const enable_shared_from_this* __p)
+ { return __p; }
+
+ template<typename>
+ friend class shared_ptr;
mutable weak_ptr<_Tp> _M_weak_this;
};
new file mode 100644
@@ -0,0 +1,47 @@
+// Copyright (C) 2016 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++14 } }
+
+#include <experimental/memory>
+#include <testsuite_hooks.h>
+
+struct A : std::enable_shared_from_this<A> { };
+struct B : std::experimental::enable_shared_from_this<B> { };
+struct C : A, B { };
+
+void
+test01()
+{
+ // This should not fail to compile due to ambiguous base classes:
+ std::experimental::shared_ptr<C> p(new C);
+
+ // And both base classes should have been enabled:
+ std::shared_ptr<A> pa = p->A::shared_from_this();
+ VERIFY( pa != nullptr );
+ // Can't compare pa and p because they're different types
+
+ std::experimental::shared_ptr<B> pb = p->B::shared_from_this();
+ VERIFY( pb != nullptr );
+ VERIFY( pb == p );
+}
+
+int
+main()
+{
+ test01();
+}
@@ -1,4 +1,4 @@
-// { dg-options "-std=gnu++14" }
+// { dg-do run { target c++14 } }
// Copyright (C) 2015-2016 Free Software Foundation, Inc.
//
@@ -61,7 +61,6 @@ static_assert( !constructible< B[], A[1] >(), "B[2] -> A[1] not compatible" );
void
test01()
{
- bool test __attribute__((unused)) = true;
std::unique_ptr<A> up(new A);
std::experimental::shared_ptr<A> sp(std::move(up));
VERIFY( up.get() == 0 );
@@ -84,7 +83,16 @@ test02()
VERIFY( sp.get() != 0 );
VERIFY( sp.use_count() == 1 );
- VERIFY( sp[0].shared_from_this() != nullptr );
+ bool caught = false;
+ try
+ {
+ sp[0].shared_from_this(); // should not be set for arrays
+ }
+ catch (const std::bad_weak_ptr&)
+ {
+ caught = true;
+ }
+ VERIFY( caught );
sp.reset();
VERIFY( destroyed == 5 );