================ @@ -0,0 +1,97 @@ +// -*- C++ -*- +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#ifndef _LIBCPP___OUT_PTR_H +#define _LIBCPP___OUT_PTR_H + +#include <__config> +#include <__memory/addressof.h> +#include <__memory/pointer_traits.h> +#include <__memory/shared_ptr.h> +#include <__memory/unique_ptr.h> +#include <__type_traits/is_specialization.h> +#include <__type_traits/is_void.h> +#include <tuple> + +#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) +# pragma GCC system_header +#endif + +_LIBCPP_BEGIN_NAMESPACE_STD + +#if _LIBCPP_STD_VER >= 23 + +template <class _Tp> +concept __resettable_adapted_ptr = requires(_Tp __ptr) { __ptr().reset(); }; + +template <class _Smart, class _Pointer, class... _Args> +class _LIBCPP_TEMPLATE_VIS out_ptr_t { + static_assert(!__is_specialization_v<_Smart, shared_ptr> || sizeof...(_Args) > 0, + "Specialization of std::shared_ptr<> requires a deleter."); + +public: + _LIBCPP_HIDE_FROM_ABI explicit out_ptr_t(_Smart& __s, _Args... __args) + : __s_(__s), __a_(std::forward<_Args>(__args)...), __p_() { + using _Ptr = decltype(__s); + if constexpr (__resettable_smart_pointer<_Ptr>) { + __s_.reset(); + } else if constexpr (is_constructible_v<_Smart>) { + __s_ = _Smart(); + } else { + static_assert(__resettable_smart_pointer<_Ptr> || is_constructible_v<_Smart>); + } + } + + _LIBCPP_HIDE_FROM_ABI out_ptr_t(const out_ptr_t&) = delete; + + _LIBCPP_HIDE_FROM_ABI ~out_ptr_t() { ---------------- ldionne wrote:
I think we need to do something about https://eel.is/c++draft/smartptr#out.ptr.t-7. Otherwise, when we use a `shared_ptr` here, if we fail to allocate the control block we'll be in trouble, since this is a destructor. So, instead what we could do is allocate a control block in the constructor, then use `shared_ptr<T>::__create_with_control_block` in the destructor. The simplest way to do this might be to create a specialization for `shared_ptr<T>`. Do you think that is overkill? https://github.com/llvm/llvm-project/pull/73618 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits