llvm-project/libcxx/include/__memory/unique_ptr.h

// -*- 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___MEMORY_UNIQUE_PTR_H
#define _LIBCPP___MEMORY_UNIQUE_PTR_H

#include <__assert>
#include <__compare/compare_three_way.h>
#include <__compare/compare_three_way_result.h>
#include <__compare/three_way_comparable.h>
#include <__config>
#include <__cstddef/nullptr_t.h>
#include <__cstddef/size_t.h>
#include <__functional/hash.h>
#include <__functional/operations.h>
#include <__memory/allocator_traits.h> // __pointer
#include <__memory/array_cookie.h>
#include <__memory/auto_ptr.h>
#include <__memory/compressed_pair.h>
#include <__memory/pointer_traits.h>
#include <__type_traits/add_lvalue_reference.h>
#include <__type_traits/common_type.h>
#include <__type_traits/conditional.h>
#include <__type_traits/dependent_type.h>
#include <__type_traits/enable_if.h>
#include <__type_traits/integral_constant.h>
#include <__type_traits/is_array.h>
#include <__type_traits/is_assignable.h>
#include <__type_traits/is_bounded_array.h>
#include <__type_traits/is_constant_evaluated.h>
#include <__type_traits/is_constructible.h>
#include <__type_traits/is_convertible.h>
#include <__type_traits/is_function.h>
#include <__type_traits/is_pointer.h>
#include <__type_traits/is_reference.h>
#include <__type_traits/is_same.h>
#include <__type_traits/is_swappable.h>
#include <__type_traits/is_trivially_relocatable.h>
#include <__type_traits/is_unbounded_array.h>
#include <__type_traits/is_void.h>
#include <__type_traits/remove_extent.h>
#include <__type_traits/type_identity.h>
#include <__utility/declval.h>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <__utility/private_constructor_tag.h>
#include <cstdint>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Tp>
struct default_delete {
  static_assert(!is_function<_Tp>::value, "default_delete cannot be instantiated for function types");

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR default_delete() _NOEXCEPT = default;

  template <class _Up, __enable_if_t<is_convertible<_Up*, _Tp*>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 default_delete(const default_delete<_Up>&) _NOEXCEPT {}

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void operator()(_Tp* __ptr) const _NOEXCEPT {
    static_assert(sizeof(_Tp) >= 0, "cannot delete an incomplete type");
    static_assert(!is_void<_Tp>::value, "cannot delete an incomplete type");
    delete __ptr;
  }
};

template <class _Tp>
struct default_delete<_Tp[]> {
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR default_delete() _NOEXCEPT = default;

  template <class _Up, __enable_if_t<is_convertible<_Up (*)[], _Tp (*)[]>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 default_delete(const default_delete<_Up[]>&) _NOEXCEPT {}

  template <class _Up, __enable_if_t<is_convertible<_Up (*)[], _Tp (*)[]>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void operator()(_Up* __ptr) const _NOEXCEPT {
    static_assert(sizeof(_Up) >= 0, "cannot delete an incomplete type");
    delete[] __ptr;
  }
};

template <class _Deleter>
inline const bool __is_default_deleter_v = false;

template <class _Tp>
inline const bool __is_default_deleter_v<default_delete<_Tp> > = true;

template <class _Deleter>
struct __unique_ptr_deleter_sfinae {
  static_assert(!is_reference<_Deleter>::value, "incorrect specialization");
  typedef const _Deleter& __lval_ref_type;
  typedef _Deleter&& __good_rval_ref_type;
  typedef true_type __enable_rval_overload;
};

template <class _Deleter>
struct __unique_ptr_deleter_sfinae<_Deleter const&> {
  typedef const _Deleter& __lval_ref_type;
  typedef const _Deleter&& __bad_rval_ref_type;
  typedef false_type __enable_rval_overload;
};

template <class _Deleter>
struct __unique_ptr_deleter_sfinae<_Deleter&> {
  typedef _Deleter& __lval_ref_type;
  typedef _Deleter&& __bad_rval_ref_type;
  typedef false_type __enable_rval_overload;
};

#if defined(_LIBCPP_ABI_ENABLE_UNIQUE_PTR_TRIVIAL_ABI)
#  define _LIBCPP_UNIQUE_PTR_TRIVIAL_ABI __attribute__((__trivial_abi__))
#else
#  define _LIBCPP_UNIQUE_PTR_TRIVIAL_ABI
#endif

template <class _Tp, class _Dp = default_delete<_Tp> >
class _LIBCPP_UNIQUE_PTR_TRIVIAL_ABI unique_ptr {
public:
  typedef _Tp element_type;
  typedef _Dp deleter_type;
  using pointer _LIBCPP_NODEBUG = __pointer<_Tp, deleter_type>;

  static_assert(!is_rvalue_reference<deleter_type>::value, "the specified deleter type cannot be an rvalue reference");

  // A unique_ptr contains the following members which may be trivially relocatable:
  // - pointer : this may be trivially relocatable, so it's checked
  // - deleter_type: this may be trivially relocatable, so it's checked
  //
  // This unique_ptr implementation only contains a pointer to the unique object and a deleter, so there are no
  // references to itself. This means that the entire structure is trivially relocatable if its members are.
  using __trivially_relocatable _LIBCPP_NODEBUG = __conditional_t<
      __libcpp_is_trivially_relocatable<pointer>::value && __libcpp_is_trivially_relocatable<deleter_type>::value,
      unique_ptr,
      void>;

private:
  _LIBCPP_COMPRESSED_PAIR(pointer, __ptr_, deleter_type, __deleter_);

  using _DeleterSFINAE _LIBCPP_NODEBUG = __unique_ptr_deleter_sfinae<_Dp>;

  template <bool _Dummy>
  using _LValRefType _LIBCPP_NODEBUG = typename __dependent_type<_DeleterSFINAE, _Dummy>::__lval_ref_type;

  template <bool _Dummy>
  using _GoodRValRefType _LIBCPP_NODEBUG = typename __dependent_type<_DeleterSFINAE, _Dummy>::__good_rval_ref_type;

  template <bool _Dummy>
  using _BadRValRefType _LIBCPP_NODEBUG = typename __dependent_type<_DeleterSFINAE, _Dummy>::__bad_rval_ref_type;

  template <bool _Dummy, class _Deleter = typename __dependent_type< __type_identity<deleter_type>, _Dummy>::type>
  using _EnableIfDeleterDefaultConstructible _LIBCPP_NODEBUG =
      __enable_if_t<is_default_constructible<_Deleter>::value && !is_pointer<_Deleter>::value>;

  template <class _ArgType>
  using _EnableIfDeleterConstructible _LIBCPP_NODEBUG = __enable_if_t<is_constructible<deleter_type, _ArgType>::value>;

  template <class _UPtr, class _Up>
  using _EnableIfMoveConvertible _LIBCPP_NODEBUG =
      __enable_if_t< is_convertible<typename _UPtr::pointer, pointer>::value && !is_array<_Up>::value >;

  template <class _UDel>
  using _EnableIfDeleterConvertible _LIBCPP_NODEBUG =
      __enable_if_t< (is_reference<_Dp>::value && is_same<_Dp, _UDel>::value) ||
                     (!is_reference<_Dp>::value && is_convertible<_UDel, _Dp>::value) >;

  template <class _UDel>
  using _EnableIfDeleterAssignable _LIBCPP_NODEBUG = __enable_if_t< is_assignable<_Dp&, _UDel&&>::value >;

public:
  template <bool _Dummy = true, class = _EnableIfDeleterDefaultConstructible<_Dummy> >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR unique_ptr() _NOEXCEPT : __ptr_(), __deleter_() {}

  template <bool _Dummy = true, class = _EnableIfDeleterDefaultConstructible<_Dummy> >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR unique_ptr(nullptr_t) _NOEXCEPT : __ptr_(), __deleter_() {}

  template <bool _Dummy = true, class = _EnableIfDeleterDefaultConstructible<_Dummy> >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 explicit unique_ptr(pointer __p) _NOEXCEPT
      : __ptr_(__p),
        __deleter_() {}

  template <bool _Dummy = true, class = _EnableIfDeleterConstructible<_LValRefType<_Dummy> > >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr(pointer __p, _LValRefType<_Dummy> __d) _NOEXCEPT
      : __ptr_(__p),
        __deleter_(__d) {}

  template <bool _Dummy = true, class = _EnableIfDeleterConstructible<_GoodRValRefType<_Dummy> > >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr(pointer __p, _GoodRValRefType<_Dummy> __d) _NOEXCEPT
      : __ptr_(__p),
        __deleter_(std::move(__d)) {
    static_assert(!is_reference<deleter_type>::value, "rvalue deleter bound to reference");
  }

  template <bool _Dummy = true, class = _EnableIfDeleterConstructible<_BadRValRefType<_Dummy> > >
  _LIBCPP_HIDE_FROM_ABI unique_ptr(pointer __p, _BadRValRefType<_Dummy> __d) = delete;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr(unique_ptr&& __u) _NOEXCEPT
      : __ptr_(__u.release()),
        __deleter_(std::forward<deleter_type>(__u.get_deleter())) {}

  template <class _Up,
            class _Ep,
            class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
            class = _EnableIfDeleterConvertible<_Ep> >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT
      : __ptr_(__u.release()),
        __deleter_(std::forward<_Ep>(__u.get_deleter())) {}

#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
  template <class _Up,
            __enable_if_t<is_convertible<_Up*, _Tp*>::value && is_same<_Dp, default_delete<_Tp> >::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI unique_ptr(auto_ptr<_Up>&& __p) _NOEXCEPT : __ptr_(__p.release()), __deleter_() {}
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr& operator=(unique_ptr&& __u) _NOEXCEPT {
    reset(__u.release());
    __deleter_ = std::forward<deleter_type>(__u.get_deleter());
    return *this;
  }

  template <class _Up,
            class _Ep,
            class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
            class = _EnableIfDeleterAssignable<_Ep> >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr& operator=(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT {
    reset(__u.release());
    __deleter_ = std::forward<_Ep>(__u.get_deleter());
    return *this;
  }

#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
  template <class _Up,
            __enable_if_t<is_convertible<_Up*, _Tp*>::value && is_same<_Dp, default_delete<_Tp> >::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI unique_ptr& operator=(auto_ptr<_Up> __p) {
    reset(__p.release());
    return *this;
  }
#endif

#ifdef _LIBCPP_CXX03_LANG
  unique_ptr(unique_ptr const&)            = delete;
  unique_ptr& operator=(unique_ptr const&) = delete;
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 ~unique_ptr() { reset(); }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr& operator=(nullptr_t) _NOEXCEPT {
    reset();
    return *this;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 __add_lvalue_reference_t<_Tp> operator*() const
      _NOEXCEPT_(_NOEXCEPT_(*std::declval<pointer>())) {
    return *__ptr_;
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 pointer operator->() const _NOEXCEPT { return __ptr_; }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 pointer get() const _NOEXCEPT { return __ptr_; }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 deleter_type& get_deleter() _NOEXCEPT { return __deleter_; }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 const deleter_type& get_deleter() const _NOEXCEPT {
    return __deleter_;
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 explicit operator bool() const _NOEXCEPT {
    return __ptr_ != nullptr;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 pointer release() _NOEXCEPT {
    pointer __t = __ptr_;
    __ptr_      = pointer();
    return __t;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void reset(pointer __p = pointer()) _NOEXCEPT {
    pointer __tmp = __ptr_;
    __ptr_        = __p;
    if (__tmp)
      __deleter_(__tmp);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void swap(unique_ptr& __u) _NOEXCEPT {
    using std::swap;
    swap(__ptr_, __u.__ptr_);
    swap(__deleter_, __u.__deleter_);
  }
};

// Bounds checking in unique_ptr<T[]>
// ==================================
//
// We provide some helper classes that allow bounds checking when accessing a unique_ptr<T[]>.
// There are a few cases where bounds checking can be implemented:
//
// 1. When an array cookie exists at the beginning of the array allocation, we are
//    able to reuse that cookie to extract the size of the array and perform bounds checking.
//    An array cookie is a size inserted at the beginning of the allocation by the compiler.
//    That size is inserted implicitly when doing `new T[n]` in some cases (as of writing this
//    exactly when the array elements are not trivially destructible), and its main purpose is
//    to allow the runtime to destroy the `n` array elements when doing `delete[] array`.
//    When we are able to use array cookies, we reuse information already available in the
//    current runtime, so bounds checking does not require changing libc++'s ABI.
//
//    However, note that we cannot assume the presence of an array cookie when a custom deleter
//    is used, because the unique_ptr could have been created from an allocation that wasn't
//    obtained via `new T[n]` (since it may not be deleted with `delete[] arr`).
//
// 2. When the "bounded unique_ptr" ABI configuration (controlled by `_LIBCPP_ABI_BOUNDED_UNIQUE_PTR`)
//    is enabled, we store the size of the allocation (when it is known) so we can check it when
//    indexing into the `unique_ptr`. That changes the layout of `std::unique_ptr<T[]>`, which is
//    an ABI break from the default configuration.
//
//    Note that even under this ABI configuration, we can't always know the size of the unique_ptr.
//    Indeed, the size of the allocation can only be known when the unique_ptr is created via
//    make_unique or a similar API. For example, it can't be known when constructed from an arbitrary
//    pointer, in which case we are not able to check the bounds on access:
//
//      unique_ptr<T[], MyDeleter> ptr(new T[3]);
//
//    When we don't know the size of the allocation via the API used to create the unique_ptr, we
//    try to fall back to using an array cookie when available.
//
//    Finally, note that when this ABI configuration is enabled, we have no choice but to always
//    make space for the size to be stored in the unique_ptr. Indeed, while we might want to avoid
//    storing the size when an array cookie is available, knowing whether an array cookie is available
//    requires the type stored in the unique_ptr to be complete, while unique_ptr can normally
//    accommodate incomplete types.
//
// (1) Implementation where we rely on the array cookie to know the size of the allocation, if
//     an array cookie exists.
struct __unique_ptr_array_bounds_stateless {
  __unique_ptr_array_bounds_stateless() = default;
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __unique_ptr_array_bounds_stateless(size_t) {}

  template <class _Deleter,
            class _Tp,
            __enable_if_t<__is_default_deleter_v<_Deleter> && __has_array_cookie<_Tp>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool __in_bounds(_Tp* __ptr, size_t __index) const {
    // In constant expressions, we can't check the array cookie so we just pretend that the index
    // is in-bounds. The compiler catches invalid accesses anyway.
    if (__libcpp_is_constant_evaluated())
      return true;
    size_t __cookie = std::__get_array_cookie(__ptr);
    return __index < __cookie;
  }

  template <class _Deleter,
            class _Tp,
            __enable_if_t<!__is_default_deleter_v<_Deleter> || !__has_array_cookie<_Tp>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool __in_bounds(_Tp*, size_t) const {
    return true; // If we don't have an array cookie, we assume the access is in-bounds
  }
};

// (2) Implementation where we store the size in the class whenever we have it.
//
// Semantically, we'd need to store the size as an optional<size_t>. However, since that
// is really heavy weight, we instead store a size_t and use SIZE_MAX as a magic value
// meaning that we don't know the size.
struct __unique_ptr_array_bounds_stored {
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __unique_ptr_array_bounds_stored() : __size_(SIZE_MAX) {}
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __unique_ptr_array_bounds_stored(size_t __size) : __size_(__size) {}

  // Use the array cookie if there's one
  template <class _Deleter,
            class _Tp,
            __enable_if_t<__is_default_deleter_v<_Deleter> && __has_array_cookie<_Tp>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool __in_bounds(_Tp* __ptr, size_t __index) const {
    if (__libcpp_is_constant_evaluated())
      return true;
    size_t __cookie = std::__get_array_cookie(__ptr);
    return __index < __cookie;
  }

  // Otherwise, fall back on the stored size (if any)
  template <class _Deleter,
            class _Tp,
            __enable_if_t<!__is_default_deleter_v<_Deleter> || !__has_array_cookie<_Tp>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool __in_bounds(_Tp*, size_t __index) const {
    return __index < __size_;
  }

private:
  size_t __size_;
};

template <class _Tp, class _Dp>
class _LIBCPP_UNIQUE_PTR_TRIVIAL_ABI unique_ptr<_Tp[], _Dp> {
public:
  typedef _Tp element_type;
  typedef _Dp deleter_type;
  using pointer = __pointer<_Tp, deleter_type>;

  // A unique_ptr contains the following members which may be trivially relocatable:
  // - pointer: this may be trivially relocatable, so it's checked
  // - deleter_type: this may be trivially relocatable, so it's checked
  // - (optionally) size: this is trivially relocatable
  //
  // This unique_ptr implementation only contains a pointer to the unique object and a deleter, so there are no
  // references to itself. This means that the entire structure is trivially relocatable if its members are.
  using __trivially_relocatable _LIBCPP_NODEBUG = __conditional_t<
      __libcpp_is_trivially_relocatable<pointer>::value && __libcpp_is_trivially_relocatable<deleter_type>::value,
      unique_ptr,
      void>;

private:
  template <class _Up, class _OtherDeleter>
  friend class unique_ptr;

  _LIBCPP_COMPRESSED_PAIR(pointer, __ptr_, deleter_type, __deleter_);
#ifdef _LIBCPP_ABI_BOUNDED_UNIQUE_PTR
  using _BoundsChecker _LIBCPP_NODEBUG = __unique_ptr_array_bounds_stored;
#else
  using _BoundsChecker _LIBCPP_NODEBUG = __unique_ptr_array_bounds_stateless;
#endif
  _LIBCPP_NO_UNIQUE_ADDRESS _BoundsChecker __checker_;

  template <class _From>
  struct _CheckArrayPointerConversion : is_same<_From, pointer> {};

  template <class _FromElem>
  struct _CheckArrayPointerConversion<_FromElem*>
      : integral_constant<bool,
                          is_same<_FromElem*, pointer>::value ||
                              (is_same<pointer, element_type*>::value &&
                               is_convertible<_FromElem (*)[], element_type (*)[]>::value) > {};

  typedef __unique_ptr_deleter_sfinae<_Dp> _DeleterSFINAE;

  template <bool _Dummy>
  using _LValRefType _LIBCPP_NODEBUG = typename __dependent_type<_DeleterSFINAE, _Dummy>::__lval_ref_type;

  template <bool _Dummy>
  using _GoodRValRefType _LIBCPP_NODEBUG = typename __dependent_type<_DeleterSFINAE, _Dummy>::__good_rval_ref_type;

  template <bool _Dummy>
  using _BadRValRefType _LIBCPP_NODEBUG = typename __dependent_type<_DeleterSFINAE, _Dummy>::__bad_rval_ref_type;

  template <bool _Dummy, class _Deleter = typename __dependent_type< __type_identity<deleter_type>, _Dummy>::type>
  using _EnableIfDeleterDefaultConstructible _LIBCPP_NODEBUG =
      __enable_if_t<is_default_constructible<_Deleter>::value && !is_pointer<_Deleter>::value>;

  template <class _ArgType>
  using _EnableIfDeleterConstructible _LIBCPP_NODEBUG = __enable_if_t<is_constructible<deleter_type, _ArgType>::value>;

  template <class _Pp>
  using _EnableIfPointerConvertible _LIBCPP_NODEBUG = __enable_if_t< _CheckArrayPointerConversion<_Pp>::value >;

  template <class _UPtr, class _Up, class _ElemT = typename _UPtr::element_type>
  using _EnableIfMoveConvertible _LIBCPP_NODEBUG =
      __enable_if_t< is_array<_Up>::value && is_same<pointer, element_type*>::value &&
                     is_same<typename _UPtr::pointer, _ElemT*>::value &&
                     is_convertible<_ElemT (*)[], element_type (*)[]>::value >;

  template <class _UDel>
  using _EnableIfDeleterConvertible _LIBCPP_NODEBUG =
      __enable_if_t< (is_reference<_Dp>::value && is_same<_Dp, _UDel>::value) ||
                     (!is_reference<_Dp>::value && is_convertible<_UDel, _Dp>::value) >;

  template <class _UDel>
  using _EnableIfDeleterAssignable _LIBCPP_NODEBUG = __enable_if_t< is_assignable<_Dp&, _UDel&&>::value >;

public:
  template <bool _Dummy = true, class = _EnableIfDeleterDefaultConstructible<_Dummy> >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR unique_ptr() _NOEXCEPT : __ptr_(), __deleter_() {}

  template <bool _Dummy = true, class = _EnableIfDeleterDefaultConstructible<_Dummy> >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR unique_ptr(nullptr_t) _NOEXCEPT : __ptr_(), __deleter_() {}

  template <class _Pp,
            bool _Dummy = true,
            class       = _EnableIfDeleterDefaultConstructible<_Dummy>,
            class       = _EnableIfPointerConvertible<_Pp> >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 explicit unique_ptr(_Pp __ptr) _NOEXCEPT
      : __ptr_(__ptr),
        __deleter_() {}

  // Private constructor used by make_unique & friends to pass the size that was allocated
  template <class _Tag, class _Ptr, __enable_if_t<is_same<_Tag, __private_constructor_tag>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 explicit unique_ptr(_Tag, _Ptr __ptr, size_t __size) _NOEXCEPT
      : __ptr_(__ptr),
        __checker_(__size) {}

  template <class _Pp,
            bool _Dummy = true,
            class       = _EnableIfDeleterConstructible<_LValRefType<_Dummy> >,
            class       = _EnableIfPointerConvertible<_Pp> >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr(_Pp __ptr, _LValRefType<_Dummy> __deleter) _NOEXCEPT
      : __ptr_(__ptr),
        __deleter_(__deleter) {}

  template <bool _Dummy = true, class = _EnableIfDeleterConstructible<_LValRefType<_Dummy> > >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr(nullptr_t, _LValRefType<_Dummy> __deleter) _NOEXCEPT
      : __ptr_(nullptr),
        __deleter_(__deleter) {}

  template <class _Pp,
            bool _Dummy = true,
            class       = _EnableIfDeleterConstructible<_GoodRValRefType<_Dummy> >,
            class       = _EnableIfPointerConvertible<_Pp> >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23
  unique_ptr(_Pp __ptr, _GoodRValRefType<_Dummy> __deleter) _NOEXCEPT
      : __ptr_(__ptr),
        __deleter_(std::move(__deleter)) {
    static_assert(!is_reference<deleter_type>::value, "rvalue deleter bound to reference");
  }

  template <bool _Dummy = true, class = _EnableIfDeleterConstructible<_GoodRValRefType<_Dummy> > >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23
  unique_ptr(nullptr_t, _GoodRValRefType<_Dummy> __deleter) _NOEXCEPT
      : __ptr_(nullptr),
        __deleter_(std::move(__deleter)) {
    static_assert(!is_reference<deleter_type>::value, "rvalue deleter bound to reference");
  }

  template <class _Pp,
            bool _Dummy = true,
            class       = _EnableIfDeleterConstructible<_BadRValRefType<_Dummy> >,
            class       = _EnableIfPointerConvertible<_Pp> >
  _LIBCPP_HIDE_FROM_ABI unique_ptr(_Pp __ptr, _BadRValRefType<_Dummy> __deleter) = delete;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr(unique_ptr&& __u) _NOEXCEPT
      : __ptr_(__u.release()),
        __deleter_(std::forward<deleter_type>(__u.get_deleter())),
        __checker_(std::move(__u.__checker_)) {}

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr& operator=(unique_ptr&& __u) _NOEXCEPT {
    reset(__u.release());
    __deleter_ = std::forward<deleter_type>(__u.get_deleter());
    __checker_ = std::move(__u.__checker_);
    return *this;
  }

  template <class _Up,
            class _Ep,
            class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
            class = _EnableIfDeleterConvertible<_Ep> >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT
      : __ptr_(__u.release()),
        __deleter_(std::forward<_Ep>(__u.get_deleter())),
        __checker_(std::move(__u.__checker_)) {}

  template <class _Up,
            class _Ep,
            class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
            class = _EnableIfDeleterAssignable<_Ep> >
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr& operator=(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT {
    reset(__u.release());
    __deleter_ = std::forward<_Ep>(__u.get_deleter());
    __checker_ = std::move(__u.__checker_);
    return *this;
  }

#ifdef _LIBCPP_CXX03_LANG
  unique_ptr(unique_ptr const&)            = delete;
  unique_ptr& operator=(unique_ptr const&) = delete;
#endif

public:
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 ~unique_ptr() { reset(); }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr& operator=(nullptr_t) _NOEXCEPT {
    reset();
    return *this;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 __add_lvalue_reference_t<_Tp> operator[](size_t __i) const {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__checker_.__in_bounds<deleter_type>(std::__to_address(__ptr_), __i),
                                        "unique_ptr<T[]>::operator[](index): index out of range");
    return __ptr_[__i];
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 pointer get() const _NOEXCEPT { return __ptr_; }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 deleter_type& get_deleter() _NOEXCEPT { return __deleter_; }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 const deleter_type& get_deleter() const _NOEXCEPT {
    return __deleter_;
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 explicit operator bool() const _NOEXCEPT {
    return __ptr_ != nullptr;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 pointer release() _NOEXCEPT {
    pointer __t = __ptr_;
    __ptr_      = pointer();
    // The deleter and the optional bounds-checker are left unchanged. The bounds-checker
    // will be reinitialized appropriately when/if the unique_ptr gets assigned-to or reset.
    return __t;
  }

  template <class _Pp, __enable_if_t<_CheckArrayPointerConversion<_Pp>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void reset(_Pp __ptr) _NOEXCEPT {
    pointer __tmp = __ptr_;
    __ptr_        = __ptr;
    __checker_    = _BoundsChecker();
    if (__tmp)
      __deleter_(__tmp);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void reset(nullptr_t = nullptr) _NOEXCEPT {
    pointer __tmp = __ptr_;
    __ptr_        = nullptr;
    __checker_    = _BoundsChecker();
    if (__tmp)
      __deleter_(__tmp);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void swap(unique_ptr& __u) _NOEXCEPT {
    using std::swap;
    swap(__ptr_, __u.__ptr_);
    swap(__deleter_, __u.__deleter_);
    swap(__checker_, __u.__checker_);
  }
};

template <class _Tp, class _Dp, __enable_if_t<__is_swappable_v<_Dp>, int> = 0>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void
swap(unique_ptr<_Tp, _Dp>& __x, unique_ptr<_Tp, _Dp>& __y) _NOEXCEPT {
  __x.swap(__y);
}

template <class _T1, class _D1, class _T2, class _D2>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool
operator==(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {
  return __x.get() == __y.get();
}

#if _LIBCPP_STD_VER <= 17
template <class _T1, class _D1, class _T2, class _D2>
inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {
  return !(__x == __y);
}
#endif

template <class _T1, class _D1, class _T2, class _D2>
inline _LIBCPP_HIDE_FROM_ABI bool operator<(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {
  typedef typename unique_ptr<_T1, _D1>::pointer _P1;
  typedef typename unique_ptr<_T2, _D2>::pointer _P2;
  typedef typename common_type<_P1, _P2>::type _Vp;
  return less<_Vp>()(__x.get(), __y.get());
}

template <class _T1, class _D1, class _T2, class _D2>
inline _LIBCPP_HIDE_FROM_ABI bool operator>(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {
  return __y < __x;
}

template <class _T1, class _D1, class _T2, class _D2>
inline _LIBCPP_HIDE_FROM_ABI bool operator<=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {
  return !(__y < __x);
}

template <class _T1, class _D1, class _T2, class _D2>
inline _LIBCPP_HIDE_FROM_ABI bool operator>=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {
  return !(__x < __y);
}

#if _LIBCPP_STD_VER >= 20
template <class _T1, class _D1, class _T2, class _D2>
  requires three_way_comparable_with<typename unique_ptr<_T1, _D1>::pointer, typename unique_ptr<_T2, _D2>::pointer>
_LIBCPP_HIDE_FROM_ABI
compare_three_way_result_t<typename unique_ptr<_T1, _D1>::pointer, typename unique_ptr<_T2, _D2>::pointer>
operator<=>(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {
  return compare_three_way()(__x.get(), __y.get());
}
#endif

template <class _T1, class _D1>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool
operator==(const unique_ptr<_T1, _D1>& __x, nullptr_t) _NOEXCEPT {
  return !__x;
}

#if _LIBCPP_STD_VER <= 17
template <class _T1, class _D1>
inline _LIBCPP_HIDE_FROM_ABI bool operator==(nullptr_t, const unique_ptr<_T1, _D1>& __x) _NOEXCEPT {
  return !__x;
}

template <class _T1, class _D1>
inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const unique_ptr<_T1, _D1>& __x, nullptr_t) _NOEXCEPT {
  return static_cast<bool>(__x);
}

template <class _T1, class _D1>
inline _LIBCPP_HIDE_FROM_ABI bool operator!=(nullptr_t, const unique_ptr<_T1, _D1>& __x) _NOEXCEPT {
  return static_cast<bool>(__x);
}
#endif // _LIBCPP_STD_VER <= 17

template <class _T1, class _D1>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator<(const unique_ptr<_T1, _D1>& __x, nullptr_t) {
  typedef typename unique_ptr<_T1, _D1>::pointer _P1;
  return less<_P1>()(__x.get(), nullptr);
}

template <class _T1, class _D1>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator<(nullptr_t, const unique_ptr<_T1, _D1>& __x) {
  typedef typename unique_ptr<_T1, _D1>::pointer _P1;
  return less<_P1>()(nullptr, __x.get());
}

template <class _T1, class _D1>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator>(const unique_ptr<_T1, _D1>& __x, nullptr_t) {
  return nullptr < __x;
}

template <class _T1, class _D1>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator>(nullptr_t, const unique_ptr<_T1, _D1>& __x) {
  return __x < nullptr;
}

template <class _T1, class _D1>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator<=(const unique_ptr<_T1, _D1>& __x, nullptr_t) {
  return !(nullptr < __x);
}

template <class _T1, class _D1>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator<=(nullptr_t, const unique_ptr<_T1, _D1>& __x) {
  return !(__x < nullptr);
}

template <class _T1, class _D1>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator>=(const unique_ptr<_T1, _D1>& __x, nullptr_t) {
  return !(__x < nullptr);
}

template <class _T1, class _D1>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator>=(nullptr_t, const unique_ptr<_T1, _D1>& __x) {
  return !(nullptr < __x);
}

#if _LIBCPP_STD_VER >= 20
template <class _T1, class _D1>
  requires three_way_comparable< typename unique_ptr<_T1, _D1>::pointer>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 compare_three_way_result_t<typename unique_ptr<_T1, _D1>::pointer>
operator<=>(const unique_ptr<_T1, _D1>& __x, nullptr_t) {
  return compare_three_way()(__x.get(), static_cast<typename unique_ptr<_T1, _D1>::pointer>(nullptr));
}
#endif

#if _LIBCPP_STD_VER >= 14

template <class _Tp, class... _Args, enable_if_t<!is_array<_Tp>::value, int> = 0>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr<_Tp> make_unique(_Args&&... __args) {
  return unique_ptr<_Tp>(new _Tp(std::forward<_Args>(__args)...));
}

template <class _Tp, enable_if_t<__is_unbounded_array_v<_Tp>, int> = 0>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr<_Tp> make_unique(size_t __n) {
  typedef __remove_extent_t<_Tp> _Up;
  return unique_ptr<_Tp>(__private_constructor_tag(), new _Up[__n](), __n);
}

template <class _Tp, class... _Args, enable_if_t<__is_bounded_array_v<_Tp>, int> = 0>
void make_unique(_Args&&...) = delete;

#endif // _LIBCPP_STD_VER >= 14

#if _LIBCPP_STD_VER >= 20

template <class _Tp, enable_if_t<!is_array_v<_Tp>, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr<_Tp> make_unique_for_overwrite() {
  return unique_ptr<_Tp>(new _Tp);
}

template <class _Tp, enable_if_t<is_unbounded_array_v<_Tp>, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unique_ptr<_Tp> make_unique_for_overwrite(size_t __n) {
  return unique_ptr<_Tp>(__private_constructor_tag(), new __remove_extent_t<_Tp>[__n], __n);
}

template <class _Tp, class... _Args, enable_if_t<is_bounded_array_v<_Tp>, int> = 0>
void make_unique_for_overwrite(_Args&&...) = delete;

#endif // _LIBCPP_STD_VER >= 20

template <class _Tp>
struct hash;

template <class _Tp, class _Dp>
#ifdef _LIBCPP_CXX03_LANG
struct hash<unique_ptr<_Tp, _Dp> >
#else
struct hash<__enable_hash_helper< unique_ptr<_Tp, _Dp>, typename unique_ptr<_Tp, _Dp>::pointer> >
#endif
{
#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_BINDER_TYPEDEFS)
  _LIBCPP_DEPRECATED_IN_CXX17 typedef unique_ptr<_Tp, _Dp> argument_type;
  _LIBCPP_DEPRECATED_IN_CXX17 typedef size_t result_type;
#endif

  _LIBCPP_HIDE_FROM_ABI size_t operator()(const unique_ptr<_Tp, _Dp>& __ptr) const {
    typedef typename unique_ptr<_Tp, _Dp>::pointer pointer;
    return hash<pointer>()(__ptr.get());
  }
};

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#endif // _LIBCPP___MEMORY_UNIQUE_PTR_H