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Differential D135548 Diff 468702 libcxx/include/__memory/shared_ptr.h

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libcxx/include/__memory/shared_ptr.h

Show First 20 Lines • Show All 585 Lines • ▼ Show 20 Lines#endif // _LIBCPP_NO_EXCEPTIONS
shared_ptr(const shared_ptr<_Yp>& __r, element_type *__p) _NOEXCEPT shared_ptr(const shared_ptr<_Yp>& __r, element_type *__p) _NOEXCEPT
: __ptr_(__p), : __ptr_(__p),
__cntrl_(__r.__cntrl_) __cntrl_(__r.__cntrl_)
{ {
if (__cntrl_) if (__cntrl_)
__cntrl_->__add_shared(); __cntrl_->__add_shared();
} }
// LWG-2996
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Please update the synopsis too.

Mordante: Please update the synopsis too.
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We (and other vendors) typically backport LWG-issue, can you do that for this issue too.

Mordante: We (and other vendors) typically backport LWG-issue, can you do that for this issue too.
pateldeevAuthorUnsubmitted
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I think back-porting to c++17 will break code that does a std::move() but relies on the fact that no move happens. Arguable this a just a bug in user code, but probably still something we don't want to change?

pateldeev: I think back-porting to c++17 will break code that does a `std::move()` but relies on the fact…
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I don't feel that we should guard against users doing bad things; updating their code to C++20 will break that scenario.

I see MSVC STL applied this change unconditionally, but libstdc++ limits it to C++20 and newer.

@jwakely is there a reason for not backporting LWG-2996 to older versions?

Mordante: I don't feel that we should guard against users doing bad things; updating their code to C++20…
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I don't remember why I only added it for C++20, but probably because it's questionable whether there was a defect. It seems more like an evolutionary change (which is why it went through LEWG) than a defect fix.

jwakely: I don't remember why I only added it for C++20, but probably because it's questionable whether…
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I don't remember why I only added it for C++20, but probably because it's questionable whether there was a defect. It seems more like an evolutionary change (which is why it went through LEWG) than a defect fix.

Thanks for the information. Then it makes sense to me to do the same in libc++. @pateldeev please leave a comment why this LWG issue isn't backported to earlier language versions.

Mordante: > I don't remember why I only added it for C++20, but probably because it's questionable…
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__cntrl_->__add_shared();
}
- #if _LIBCPP_STD_VER > 20
+ #if _LIBCPP_STD_VER > 17
template <class _Yp>

Or remove it entirely.

Mordante: Or remove it entirely.
// We don't backport because it is an evolutionary change.
#if _LIBCPP_STD_VER > 20
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template <class _Yp>
- _LIBCPP_HIDE_FROM_ABI shared_ptr(shared_ptr<_Yp>&& __r, element_type* __p) _NOEXCEPT
+ _LIBCPP_HIDE_FROM_ABI shared_ptr(shared_ptr<_Yp>&& __r, element_type* __p) noexcept
: __ptr_(__p),
Mordante:
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// We don't backport because it is an evolutionary change.
- #if _LIBCPP_STD_VER > 20
+ #if _LIBCPP_STD_VER >= 20
template <class _Yp>

The LWG issue is against C++20. Same for the other changes.

philnik: The LWG issue is against C++20. Same for the other changes.
template <class _Yp>
_LIBCPP_HIDE_FROM_ABI shared_ptr(shared_ptr<_Yp>&& __r, element_type* __p) noexcept
: __ptr_(__p),
__cntrl_(__r.__cntrl_) {
__r.__ptr_ = nullptr;
__r.__cntrl_ = nullptr;
}
#endif
_LIBCPP_HIDE_FROM_ABI _LIBCPP_HIDE_FROM_ABI
shared_ptr(const shared_ptr& __r) _NOEXCEPT shared_ptr(const shared_ptr& __r) _NOEXCEPT
: __ptr_(__r.__ptr_), : __ptr_(__r.__ptr_),
__cntrl_(__r.__cntrl_) __cntrl_(__r.__cntrl_)
{ {
if (__cntrl_) if (__cntrl_)
__cntrl_->__add_shared(); __cntrl_->__add_shared();
} }
▲ Show 20 Lines • Show All 61 Lines • ▼ Show 20 Lines
#if _LIBCPP_STD_VER > 11 #if _LIBCPP_STD_VER > 11
if (__ptr_ == nullptr) if (__ptr_ == nullptr)
__cntrl_ = nullptr; __cntrl_ = nullptr;
else else
#endif #endif
{ {
typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT; typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer, _Dp, _AllocT> _CntrlBlk; typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer, _Dp, _AllocT> _CntrlBlk;
__cntrl_ = new _CntrlBlk(__r.get(), std::move(__r.get_deleter()), _AllocT()); __cntrl_ = new _CntrlBlk(__r.get(), std::move(__r.get_deleter()), _AllocT());
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Please undo this change. In the past we used _VSTD instead of std. We don't change all existing code to avoid breaking too much work in progress, but we use it when changing code.

Mordante: Please undo this change. In the past we used `_VSTD` instead of `std`. We don't change all…
__enable_weak_this(__r.get(), __r.get()); __enable_weak_this(__r.get(), __r.get());
} }
__r.release(); __r.release();
} }
template <class _Yp, class _Dp, class = void, class = __enable_if_t< template <class _Yp, class _Dp, class = void, class = __enable_if_t<
is_lvalue_reference<_Dp>::value && is_lvalue_reference<_Dp>::value &&
is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value
▲ Show 20 Lines • Show All 688 Lines • ▼ Show 20 Lines
shared_ptr<_Tp> shared_ptr<_Tp>
static_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT static_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
{ {
return shared_ptr<_Tp>(__r, return shared_ptr<_Tp>(__r,
static_cast< static_cast<
typename shared_ptr<_Tp>::element_type*>(__r.get())); typename shared_ptr<_Tp>::element_type*>(__r.get()));
} }
// LWG-2996
// We don't backport because it is an evolutionary change.
#if _LIBCPP_STD_VER > 20
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template <class _Tp, class _Up>
- inline _LIBCPP_INLINE_VISIBILITY shared_ptr<_Tp> static_pointer_cast(shared_ptr<_Up>&& __r) _NOEXCEPT {
+ _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> static_pointer_cast(shared_ptr<_Up>&& __r) noexcept {
return shared_ptr<_Tp>(_VSTD::move(__r), static_cast<typename shared_ptr<_Tp>::element_type*>(__r.get()));

_LIBCPP_HIDE_FROM_ABI is the new name for _LIBCPP_INLINE_VISIBILITY.

Mordante: `_LIBCPP_HIDE_FROM_ABI` is the new name for `_LIBCPP_INLINE_VISIBILITY`.
template <class _Tp, class _Up>
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inline _LIBCPP_INLINE_VISIBILITY shared_ptr<_Tp> static_pointer_cast(shared_ptr<_Up>&& __r) _NOEXCEPT {
- return shared_ptr<_Tp>(_VSTD::move(__r), static_cast<typename shared_ptr<_Tp>::element_type*>(__r.get()));
+ return shared_ptr<_Tp>(std::move(__r), static_cast<typename shared_ptr<_Tp>::element_type*>(__r.get()));
}
#endif
Mordante:
_LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> static_pointer_cast(shared_ptr<_Up>&& __r) noexcept {
return shared_ptr<_Tp>(std::move(__r), static_cast<typename shared_ptr<_Tp>::element_type*>(__r.get()));
}
#endif
template<class _Tp, class _Up> template<class _Tp, class _Up>
inline _LIBCPP_INLINE_VISIBILITY inline _LIBCPP_INLINE_VISIBILITY
shared_ptr<_Tp> shared_ptr<_Tp>
dynamic_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT dynamic_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
{ {
typedef typename shared_ptr<_Tp>::element_type _ET; typedef typename shared_ptr<_Tp>::element_type _ET;
_ET* __p = dynamic_cast<_ET*>(__r.get()); _ET* __p = dynamic_cast<_ET*>(__r.get());
return __p ? shared_ptr<_Tp>(__r, __p) : shared_ptr<_Tp>(); return __p ? shared_ptr<_Tp>(__r, __p) : shared_ptr<_Tp>();
} }
// LWG-2996
// We don't backport because it is an evolutionary change.
#if _LIBCPP_STD_VER > 20
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See above.

Mordante: See above.
template <class _Tp, class _Up>
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inline _LIBCPP_INLINE_VISIBILITY shared_ptr<_Tp> dynamic_pointer_cast(shared_ptr<_Up>&& __r) _NOEXCEPT {
- typedef typename shared_ptr<_Tp>::element_type _ET;
+ using _ET =typename shared_ptr<_Tp>::element_type;
_ET* __p = dynamic_cast<_ET*>(__r.get());

In new code we prefer using over typedef.

Mordante: In new code we prefer `using` over `typedef`.
_LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> dynamic_pointer_cast(shared_ptr<_Up>&& __r) noexcept {
auto* __p = dynamic_cast<typename shared_ptr<_Tp>::element_type*>(__r.get());
return __p ? shared_ptr<_Tp>(std::move(__r), __p) : shared_ptr<_Tp>();
}
#endif
template<class _Tp, class _Up> template<class _Tp, class _Up>
_LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
const_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT const_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
{ {
typedef typename shared_ptr<_Tp>::element_type _RTp; typedef typename shared_ptr<_Tp>::element_type _RTp;
return shared_ptr<_Tp>(__r, const_cast<_RTp*>(__r.get())); return shared_ptr<_Tp>(__r, const_cast<_RTp*>(__r.get()));
} }
// LWG-2996
// We don't backport because it is an evolutionary change.
#if _LIBCPP_STD_VER > 20
template <class _Tp, class _Up>
_LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> const_pointer_cast(shared_ptr<_Up>&& __r) noexcept {
return shared_ptr<_Tp>(std::move(__r), const_cast<typename shared_ptr<_Tp>::element_type*>(__r.get()));
}
#endif
template<class _Tp, class _Up> template<class _Tp, class _Up>
_LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> _LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp>
reinterpret_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT reinterpret_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
{ {
return shared_ptr<_Tp>(__r, return shared_ptr<_Tp>(__r,
reinterpret_cast< reinterpret_cast<
typename shared_ptr<_Tp>::element_type*>(__r.get())); typename shared_ptr<_Tp>::element_type*>(__r.get()));
} }
// LWG-2996
// We don't backport because it is an evolutionary change.
#if _LIBCPP_STD_VER > 20
template <class _Tp, class _Up>
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_LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> reinterpret_pointer_cast(shared_ptr<_Up>&& __r) _NOEXCEPT {
- return shared_ptr<_Tp>(_VSTD::move(__r), reinterpret_cast< typename shared_ptr<_Tp>::element_type*>(__r.get()));
+ return shared_ptr<_Tp>(_VSTD::move(__r), reinterpret_cast<typename shared_ptr<_Tp>::element_type*>(__r.get()));
}
#endif

The extra space isn't fixed by clang-format due to C++03 compatibility.

Mordante: The extra space isn't fixed by clang-format due to C++03 compatibility.
_LIBCPP_HIDE_FROM_ABI shared_ptr<_Tp> reinterpret_pointer_cast(shared_ptr<_Up>&& __r) noexcept {
return shared_ptr<_Tp>(std::move(__r), reinterpret_cast<typename shared_ptr<_Tp>::element_type*>(__r.get()));
}
#endif
#ifndef _LIBCPP_NO_RTTI #ifndef _LIBCPP_NO_RTTI
template<class _Dp, class _Tp> template<class _Dp, class _Tp>
inline _LIBCPP_INLINE_VISIBILITY inline _LIBCPP_INLINE_VISIBILITY
_Dp* _Dp*
get_deleter(const shared_ptr<_Tp>& __p) _NOEXCEPT get_deleter(const shared_ptr<_Tp>& __p) _NOEXCEPT
{ {
return __p.template __get_deleter<_Dp>(); return __p.template __get_deleter<_Dp>();
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