[libc++] Split various components out of <memory>

[• Quuxplusone]

Here are the dependency graphs before and after this patch.
At the introduction of the new grapher script, pre- D99309: https://i.imgur.com/wIGKMXG.png (10031 x 1602 pixels, 141 nodes)
Main, pre-this-patch: https://i.imgur.com/CDUSXcr.png (10360 x 1845 pixels, 141 nodes)
After this patch: https://i.imgur.com/7mll7PC.png (11243 x 2636 pixels, 150 nodes)

libcxx/include/__memory/gc.h

10–11

I suggest (well, I continue to suggest that you not do any of this refactoring, but...) that you name this file pointer_safety.h, since gc.h is (A) terse and (B) obscure. pointer_safety.h would have the benefit of matching a name in the standard (so it's greppable), and also connoting how arcane this stuff is meant to be. gc.h sounds like it might be talking about shared_ptr or something.

libcxx/include/__memory/uninitialized.h

10–11

uninitialized_algorithms.h

libcxx/include/__memory/unique_ptr.h

16

This is a very surprising edge, since ultimately we want to remove auto_ptr altogether. Can you try to remove it? (At the very least, comment why it's here.)

[ldionne]

Fix failing tests, rename headers as suggested by reviewers.

[ldionne]

In D100318#2683513, @Quuxplusone wrote:

Here are the dependency graphs before and after this patch.
At the introduction of the new grapher script, pre- D99309: https://i.imgur.com/wIGKMXG.png (10031 x 1602 pixels, 141 nodes)
Main, pre-this-patch: https://i.imgur.com/CDUSXcr.png (10360 x 1845 pixels, 141 nodes)
After this patch: https://i.imgur.com/7mll7PC.png (11243 x 2636 pixels, 150 nodes)

I disagree with the way you calculate complexity. Yes, the graph has more nodes and edges. But each file now contains a set of logically-related things, and is much smaller. As a human, I spend time reading files with code in it, not looking at graphs. The graph is useful as a tool, but it's not measure of success in itself.

libcxx/include/__memory/gc.h

10–11

I agree with pointer_safety.h, that's a much better name. Thanks.

libcxx/include/__memory/uninitialized.h

10–11

Better indeed, thanks.

libcxx/include/__memory/unique_ptr.h

16

After the move is done, I will go back and make this dependent on the standard version and whether auto_ptr is force-enabled. I didn't want to change any code as part of these commits.

[• Quuxplusone]

I disagree with the way you calculate complexity. Yes, the graph has more nodes and edges. But each file now contains a set of logically-related things, and is much smaller. As a human, I spend time reading files with code in it, not looking at graphs.

Me too! ;) When I'm reading that code, though, I tend to stumble over two measures of complexity:
(1) How hard do I have to look to find the source file that actually contains the thing I'm working on? (Once the right file is open, I can jump to the right line quickly; but I don't use an IDE that can jump me to the right file quickly.)
(2) How tightly entangled is this source file with other source files? (How many other files do I need to read in order to fully understand the code in this file?)
These two measures of complexity map directly onto "number of nodes in the graph" and "number of edges in the graph."
I do think minimizing edges is generally more important than minimizing nodes (and of course it's most important to keep the number of cycles at 0). Minimizing the diameter of the graph (the number of levels of abstraction you have to dig through to work on the code) is also relevant, if maybe less important than the other measures listed here.

libcxx/include/__memory/unique_ptr.h

16

Ah, I get it now — the culprit is literally the constructor unique_ptr(auto_ptr<Y>&&), which is removed only in C++20. Okay (although I'd still prefer to see the code comment // std::auto_ptr for clarity).

[ldionne]

Workaround failures on Clang 10

[ldionne]

@DavidSpickett Would it be possible to upgrade the ARM bots to Clang 11? They are currently running Clang 10, which is still supported for now, however it is missing 05eedf1f5b44, which makes some tests fail: https://buildkite.com/llvm-project/libcxx-ci/builds/2462#d220f5f2-25ed-498b-88e3-0013c0b5e3a1.

[DavidSpickett]

Arm bots are now on clang 11.1.0.

[ldionne]

In D100318#2685374, @DavidSpickett wrote:

Arm bots are now on clang 11.1.0.

Thanks for the prompt reply!

libcxx/include/CMakeLists.txt

set(files
   __functional_base_03
   __hash_table
   __libcpp_version
   __locale
   __memory/allocator.h
   __memory/allocator_traits.h
   __memory/auto_ptr.h
   __memory/base.h
+  __memory/compressed_pair.h
+  __memory/gc.h
   __memory/pointer_traits.h
+  __memory/raw_storage_iterator.h
+  __memory/shared_ptr.h
   __memory/temporary_buffer.h
+  __memory/uninitialized.h
+  __memory/unique_ptr.h
   __memory/utilities.h
   __mutex_base
   __node_handle
   __nullptr
   __split_buffer
   __sso_allocator
   __std_stream
   __string

libcxx/include/__memory/compressed_pair.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_COMPRESSED_PAIR_H
+#define _LIBCPP___MEMORY_COMPRESSED_PAIR_H
+
+#include <__config>
+#include <tuple> // needed in c++03 for some constructors
+#include <type_traits>
+#include <utility>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// Tag used to default initialize one or both of the pair's elements.
+struct __default_init_tag {};
+struct __value_init_tag {};
+
+template <class _Tp, int _Idx,
+          bool _CanBeEmptyBase =
+              is_empty<_Tp>::value && !__libcpp_is_final<_Tp>::value>
+struct __compressed_pair_elem {
+  typedef _Tp _ParamT;
+  typedef _Tp& reference;
+  typedef const _Tp& const_reference;
+
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+  __compressed_pair_elem(__default_init_tag) {}
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+  __compressed_pair_elem(__value_init_tag) : __value_() {}
+
+  template <class _Up, class = typename enable_if<
+      !is_same<__compressed_pair_elem, typename decay<_Up>::type>::value
+  >::type>
+  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_CONSTEXPR explicit
+  __compressed_pair_elem(_Up&& __u)
+      : __value_(_VSTD::forward<_Up>(__u))
+    {
+    }
+
+
+#ifndef _LIBCPP_CXX03_LANG
+  template <class... _Args, size_t... _Indexes>
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+  __compressed_pair_elem(piecewise_construct_t, tuple<_Args...> __args,
+                         __tuple_indices<_Indexes...>)
+      : __value_(_VSTD::forward<_Args>(_VSTD::get<_Indexes>(__args))...) {}
+#endif
+
+
+  _LIBCPP_INLINE_VISIBILITY reference __get() _NOEXCEPT { return __value_; }
+  _LIBCPP_INLINE_VISIBILITY
+  const_reference __get() const _NOEXCEPT { return __value_; }
+
+private:
+  _Tp __value_;
+};
+
+template <class _Tp, int _Idx>
+struct __compressed_pair_elem<_Tp, _Idx, true> : private _Tp {
+  typedef _Tp _ParamT;
+  typedef _Tp& reference;
+  typedef const _Tp& const_reference;
+  typedef _Tp __value_type;
+
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR __compressed_pair_elem() = default;
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+  __compressed_pair_elem(__default_init_tag) {}
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+  __compressed_pair_elem(__value_init_tag) : __value_type() {}
+
+  template <class _Up, class = typename enable_if<
+        !is_same<__compressed_pair_elem, typename decay<_Up>::type>::value
+  >::type>
+  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_CONSTEXPR explicit
+  __compressed_pair_elem(_Up&& __u)
+      : __value_type(_VSTD::forward<_Up>(__u))
+  {}
+
+#ifndef _LIBCPP_CXX03_LANG
+  template <class... _Args, size_t... _Indexes>
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+  __compressed_pair_elem(piecewise_construct_t, tuple<_Args...> __args,
+                         __tuple_indices<_Indexes...>)
+      : __value_type(_VSTD::forward<_Args>(_VSTD::get<_Indexes>(__args))...) {}
+#endif
+
+  _LIBCPP_INLINE_VISIBILITY reference __get() _NOEXCEPT { return *this; }
+  _LIBCPP_INLINE_VISIBILITY
+  const_reference __get() const _NOEXCEPT { return *this; }
+};
+
+template <class _T1, class _T2>
+class __compressed_pair : private __compressed_pair_elem<_T1, 0>,
+                          private __compressed_pair_elem<_T2, 1> {
+public:
+  // NOTE: This static assert should never fire because __compressed_pair
+  // is *almost never* used in a scenario where it's possible for T1 == T2.
+  // (The exception is std::function where it is possible that the function
+  //  object and the allocator have the same type).
+  static_assert((!is_same<_T1, _T2>::value),
+    "__compressed_pair cannot be instantiated when T1 and T2 are the same type; "
+    "The current implementation is NOT ABI-compatible with the previous "
+    "implementation for this configuration");
+
+    typedef _LIBCPP_NODEBUG_TYPE __compressed_pair_elem<_T1, 0> _Base1;
+    typedef _LIBCPP_NODEBUG_TYPE __compressed_pair_elem<_T2, 1> _Base2;
+
+    template <bool _Dummy = true,
+      class = typename enable_if<
+          __dependent_type<is_default_constructible<_T1>, _Dummy>::value &&
+          __dependent_type<is_default_constructible<_T2>, _Dummy>::value
+      >::type
+  >
+  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_CONSTEXPR __compressed_pair() : _Base1(__value_init_tag()), _Base2(__value_init_tag()) {}
+
+  template <class _U1, class _U2>
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+  __compressed_pair(_U1&& __t1, _U2&& __t2)
+      : _Base1(_VSTD::forward<_U1>(__t1)), _Base2(_VSTD::forward<_U2>(__t2)) {}
+
+#ifndef _LIBCPP_CXX03_LANG
+  template <class... _Args1, class... _Args2>
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+  __compressed_pair(piecewise_construct_t __pc, tuple<_Args1...> __first_args,
+                    tuple<_Args2...> __second_args)
+      : _Base1(__pc, _VSTD::move(__first_args),
+               typename __make_tuple_indices<sizeof...(_Args1)>::type()),
+        _Base2(__pc, _VSTD::move(__second_args),
+               typename __make_tuple_indices<sizeof...(_Args2)>::type()) {}
+#endif
+
+  _LIBCPP_INLINE_VISIBILITY
+  typename _Base1::reference first() _NOEXCEPT {
+    return static_cast<_Base1&>(*this).__get();
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  typename _Base1::const_reference first() const _NOEXCEPT {
+    return static_cast<_Base1 const&>(*this).__get();
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  typename _Base2::reference second() _NOEXCEPT {
+    return static_cast<_Base2&>(*this).__get();
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  typename _Base2::const_reference second() const _NOEXCEPT {
+    return static_cast<_Base2 const&>(*this).__get();
+  }
+
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+  static _Base1* __get_first_base(__compressed_pair* __pair) _NOEXCEPT {
+    return static_cast<_Base1*>(__pair);
+  }
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+  static _Base2* __get_second_base(__compressed_pair* __pair) _NOEXCEPT {
+    return static_cast<_Base2*>(__pair);
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  void swap(__compressed_pair& __x)
+    _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
+               __is_nothrow_swappable<_T2>::value)
+  {
+    using _VSTD::swap;
+    swap(first(), __x.first());
+    swap(second(), __x.second());
+  }
+};
+
+template <class _T1, class _T2>
+inline _LIBCPP_INLINE_VISIBILITY
+void swap(__compressed_pair<_T1, _T2>& __x, __compressed_pair<_T1, _T2>& __y)
+    _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
+               __is_nothrow_swappable<_T2>::value) {
+  __x.swap(__y);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif  // _LIBCPP___MEMORY_COMPRESSED_PAIR_H

libcxx/include/__memory/gc.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_GC_H
+#define _LIBCPP___MEMORY_GC_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+//enum class
+#if defined(_LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE)
+# ifndef _LIBCPP_CXX03_LANG
+enum class pointer_safety : unsigned char {
+  relaxed,
+  preferred,
+  strict
+};
+# endif
+#else
+struct _LIBCPP_TYPE_VIS pointer_safety
+{
+    enum __lx
+    {
+        relaxed,
+        preferred,
+        strict
+    };
+
+    __lx __v_;
+
+    _LIBCPP_INLINE_VISIBILITY
+    pointer_safety() : __v_() {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    pointer_safety(__lx __v) : __v_(__v) {}
+    _LIBCPP_INLINE_VISIBILITY
+    operator int() const {return __v_;}
+};
+#endif
+
+#if !defined(_LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE) && \
+    defined(_LIBCPP_BUILDING_LIBRARY)
+_LIBCPP_FUNC_VIS pointer_safety get_pointer_safety() _NOEXCEPT;
+#else
+// This function is only offered in C++03 under ABI v1.
+# if !defined(_LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE) || !defined(_LIBCPP_CXX03_LANG)
+inline _LIBCPP_INLINE_VISIBILITY
+pointer_safety get_pointer_safety() _NOEXCEPT {
+  return pointer_safety::relaxed;
+}
+# endif
+#endif
+
+
+_LIBCPP_FUNC_VIS void declare_reachable(void* __p);
+_LIBCPP_FUNC_VIS void declare_no_pointers(char* __p, size_t __n);
+_LIBCPP_FUNC_VIS void undeclare_no_pointers(char* __p, size_t __n);
+_LIBCPP_FUNC_VIS void* __undeclare_reachable(void* __p);
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_Tp*
+undeclare_reachable(_Tp* __p)
+{
+    return static_cast<_Tp*>(__undeclare_reachable(__p));
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif  // _LIBCPP___MEMORY_GC_H

libcxx/include/__memory/raw_storage_iterator.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_RAW_STORAGE_ITERATOR_H
+#define _LIBCPP___MEMORY_RAW_STORAGE_ITERATOR_H
+
+#include <__config>
+#include <__memory/base.h> // addressof
+#include <cstddef>
+#include <iterator>
+#include <utility>
+
+#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 _OutputIterator, class _Tp>
+class _LIBCPP_TEMPLATE_VIS raw_storage_iterator
+    : public iterator<output_iterator_tag,
+                      _Tp,                                         // purposefully not C++03
+                      ptrdiff_t,                                   // purposefully not C++03
+                      _Tp*,                                        // purposefully not C++03
+                      raw_storage_iterator<_OutputIterator, _Tp>&> // purposefully not C++03
+{
+private:
+    _OutputIterator __x_;
+public:
+    _LIBCPP_INLINE_VISIBILITY explicit raw_storage_iterator(_OutputIterator __x) : __x_(__x) {}
+    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator*() {return *this;}
+    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator=(const _Tp& __element)
+        {::new ((void*)_VSTD::addressof(*__x_)) _Tp(__element); return *this;}
+#if _LIBCPP_STD_VER >= 14
+    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator=(_Tp&& __element)
+        {::new ((void*)_VSTD::addressof(*__x_)) _Tp(_VSTD::move(__element)); return *this;}
+#endif
+    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator++() {++__x_; return *this;}
+    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator  operator++(int)
+        {raw_storage_iterator __t(*this); ++__x_; return __t;}
+#if _LIBCPP_STD_VER >= 14
+    _LIBCPP_INLINE_VISIBILITY _OutputIterator base() const { return __x_; }
+#endif
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif  // _LIBCPP___MEMORY_RAW_STORAGE_ITERATOR_H

libcxx/include/__memory/shared_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_SHARED_PTR_H
+#define _LIBCPP___MEMORY_SHARED_PTR_H
+
+#include <__config>
+#include <__availability>
+#include <__functional_base> // std::less, std::binary_function
+#include <__memory/allocator.h>
+#include <__memory/allocator_traits.h>
+#include <__memory/auto_ptr.h>
+#include <__memory/base.h> // std::addressof
+#include <__memory/compressed_pair.h>
+#include <__memory/pointer_traits.h>
+#include <__memory/unique_ptr.h>
+#include <__memory/utilities.h> // __allocation_guard
+#include <cstddef>
+#include <cstdlib> // abort
+#include <iosfwd>
+#include <stdexcept>
+#include <type_traits>
+#include <utility>
+#if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
+#  include <atomic>
+#endif
+
+#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 _Alloc>
+class __allocator_destructor
+{
+    typedef _LIBCPP_NODEBUG_TYPE allocator_traits<_Alloc> __alloc_traits;
+public:
+    typedef _LIBCPP_NODEBUG_TYPE typename __alloc_traits::pointer pointer;
+    typedef _LIBCPP_NODEBUG_TYPE typename __alloc_traits::size_type size_type;
+private:
+    _Alloc& __alloc_;
+    size_type __s_;
+public:
+    _LIBCPP_INLINE_VISIBILITY __allocator_destructor(_Alloc& __a, size_type __s)
+             _NOEXCEPT
+        : __alloc_(__a), __s_(__s) {}
+    _LIBCPP_INLINE_VISIBILITY
+    void operator()(pointer __p) _NOEXCEPT
+        {__alloc_traits::deallocate(__alloc_, __p, __s_);}
+};
+
+// NOTE: Relaxed and acq/rel atomics (for increment and decrement respectively)
+// should be sufficient for thread safety.
+// See https://llvm.org/PR22803
+#if defined(__clang__) && __has_builtin(__atomic_add_fetch)          \
+                       && defined(__ATOMIC_RELAXED)                  \
+                       && defined(__ATOMIC_ACQ_REL)
+#   define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT
+#elif defined(_LIBCPP_COMPILER_GCC)
+#   define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT
+#endif
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_relaxed_load(_ValueType const* __value) {
+#if !defined(_LIBCPP_HAS_NO_THREADS) && \
+    defined(__ATOMIC_RELAXED) &&        \
+    (__has_builtin(__atomic_load_n) || defined(_LIBCPP_COMPILER_GCC))
+    return __atomic_load_n(__value, __ATOMIC_RELAXED);
+#else
+    return *__value;
+#endif
+}
+
+template <class _ValueType>
+inline _LIBCPP_INLINE_VISIBILITY
+_ValueType __libcpp_acquire_load(_ValueType const* __value) {
+#if !defined(_LIBCPP_HAS_NO_THREADS) && \
+    defined(__ATOMIC_ACQUIRE) &&        \
+    (__has_builtin(__atomic_load_n) || defined(_LIBCPP_COMPILER_GCC))
+    return __atomic_load_n(__value, __ATOMIC_ACQUIRE);
+#else
+    return *__value;
+#endif
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _Tp
+__libcpp_atomic_refcount_increment(_Tp& __t) _NOEXCEPT
+{
+#if defined(_LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT) && !defined(_LIBCPP_HAS_NO_THREADS)
+    return __atomic_add_fetch(&__t, 1, __ATOMIC_RELAXED);
+#else
+    return __t += 1;
+#endif
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _Tp
+__libcpp_atomic_refcount_decrement(_Tp& __t) _NOEXCEPT
+{
+#if defined(_LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT) && !defined(_LIBCPP_HAS_NO_THREADS)
+    return __atomic_add_fetch(&__t, -1, __ATOMIC_ACQ_REL);
+#else
+    return __t -= 1;
+#endif
+}
+
+class _LIBCPP_EXCEPTION_ABI bad_weak_ptr
+    : public std::exception
+{
+public:
+    bad_weak_ptr() _NOEXCEPT = default;
+    bad_weak_ptr(const bad_weak_ptr&) _NOEXCEPT = default;
+    virtual ~bad_weak_ptr() _NOEXCEPT;
+    virtual const char* what() const  _NOEXCEPT;
+};
+
+_LIBCPP_NORETURN inline _LIBCPP_INLINE_VISIBILITY
+void __throw_bad_weak_ptr()
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    throw bad_weak_ptr();
+#else
+    _VSTD::abort();
+#endif
+}
+
+template<class _Tp> class _LIBCPP_TEMPLATE_VIS weak_ptr;
+
+class _LIBCPP_TYPE_VIS __shared_count
+{
+    __shared_count(const __shared_count&);
+    __shared_count& operator=(const __shared_count&);
+
+protected:
+    long __shared_owners_;
+    virtual ~__shared_count();
+private:
+    virtual void __on_zero_shared() _NOEXCEPT = 0;
+
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __shared_count(long __refs = 0) _NOEXCEPT
+        : __shared_owners_(__refs) {}
+
+#if defined(_LIBCPP_BUILDING_LIBRARY) && \
+    defined(_LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS)
+    void __add_shared() _NOEXCEPT;
+    bool __release_shared() _NOEXCEPT;
+#else
+    _LIBCPP_INLINE_VISIBILITY
+    void __add_shared() _NOEXCEPT {
+      __libcpp_atomic_refcount_increment(__shared_owners_);
+    }
+    _LIBCPP_INLINE_VISIBILITY
+    bool __release_shared() _NOEXCEPT {
+      if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1) {
+        __on_zero_shared();
+        return true;
+      }
+      return false;
+    }
+#endif
+    _LIBCPP_INLINE_VISIBILITY
+    long use_count() const _NOEXCEPT {
+        return __libcpp_relaxed_load(&__shared_owners_) + 1;
+    }
+};
+
+class _LIBCPP_TYPE_VIS __shared_weak_count
+    : private __shared_count
+{
+    long __shared_weak_owners_;
+
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __shared_weak_count(long __refs = 0) _NOEXCEPT
+        : __shared_count(__refs),
+          __shared_weak_owners_(__refs) {}
+protected:
+    virtual ~__shared_weak_count();
+
+public:
+#if defined(_LIBCPP_BUILDING_LIBRARY) && \
+    defined(_LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS)
+    void __add_shared() _NOEXCEPT;
+    void __add_weak() _NOEXCEPT;
+    void __release_shared() _NOEXCEPT;
+#else
+    _LIBCPP_INLINE_VISIBILITY
+    void __add_shared() _NOEXCEPT {
+      __shared_count::__add_shared();
+    }
+    _LIBCPP_INLINE_VISIBILITY
+    void __add_weak() _NOEXCEPT {
+      __libcpp_atomic_refcount_increment(__shared_weak_owners_);
+    }
+    _LIBCPP_INLINE_VISIBILITY
+    void __release_shared() _NOEXCEPT {
+      if (__shared_count::__release_shared())
+        __release_weak();
+    }
+#endif
+    void __release_weak() _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    long use_count() const _NOEXCEPT {return __shared_count::use_count();}
+    __shared_weak_count* lock() _NOEXCEPT;
+
+    virtual const void* __get_deleter(const type_info&) const _NOEXCEPT;
+private:
+    virtual void __on_zero_shared_weak() _NOEXCEPT = 0;
+};
+
+template <class _Tp, class _Dp, class _Alloc>
+class __shared_ptr_pointer
+    : public __shared_weak_count
+{
+    __compressed_pair<__compressed_pair<_Tp, _Dp>, _Alloc> __data_;
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    __shared_ptr_pointer(_Tp __p, _Dp __d, _Alloc __a)
+        :  __data_(__compressed_pair<_Tp, _Dp>(__p, _VSTD::move(__d)), _VSTD::move(__a)) {}
+
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* __get_deleter(const type_info&) const _NOEXCEPT;
+#endif
+
+private:
+    virtual void __on_zero_shared() _NOEXCEPT;
+    virtual void __on_zero_shared_weak() _NOEXCEPT;
+};
+
+#ifndef _LIBCPP_NO_RTTI
+
+template <class _Tp, class _Dp, class _Alloc>
+const void*
+__shared_ptr_pointer<_Tp, _Dp, _Alloc>::__get_deleter(const type_info& __t) const _NOEXCEPT
+{
+    return __t == typeid(_Dp) ? _VSTD::addressof(__data_.first().second()) : nullptr;
+}
+
+#endif  // _LIBCPP_NO_RTTI
+
+template <class _Tp, class _Dp, class _Alloc>
+void
+__shared_ptr_pointer<_Tp, _Dp, _Alloc>::__on_zero_shared() _NOEXCEPT
+{
+    __data_.first().second()(__data_.first().first());
+    __data_.first().second().~_Dp();
+}
+
+template <class _Tp, class _Dp, class _Alloc>
+void
+__shared_ptr_pointer<_Tp, _Dp, _Alloc>::__on_zero_shared_weak() _NOEXCEPT
+{
+    typedef typename __allocator_traits_rebind<_Alloc, __shared_ptr_pointer>::type _Al;
+    typedef allocator_traits<_Al> _ATraits;
+    typedef pointer_traits<typename _ATraits::pointer> _PTraits;
+
+    _Al __a(__data_.second());
+    __data_.second().~_Alloc();
+    __a.deallocate(_PTraits::pointer_to(*this), 1);
+}
+
+template <class _Tp, class _Alloc>
+struct __shared_ptr_emplace
+    : __shared_weak_count
+{
+    template<class ..._Args>
+    _LIBCPP_HIDE_FROM_ABI
+    explicit __shared_ptr_emplace(_Alloc __a, _Args&& ...__args)
+        : __storage_(_VSTD::move(__a))
+    {
+#if _LIBCPP_STD_VER > 17
+        using _TpAlloc = typename __allocator_traits_rebind<_Alloc, _Tp>::type;
+        _TpAlloc __tmp(*__get_alloc());
+        allocator_traits<_TpAlloc>::construct(__tmp, __get_elem(), _VSTD::forward<_Args>(__args)...);
+#else
+        ::new ((void*)__get_elem()) _Tp(_VSTD::forward<_Args>(__args)...);
+#endif
+    }
+
+    _LIBCPP_HIDE_FROM_ABI
+    _Alloc* __get_alloc() _NOEXCEPT { return __storage_.__get_alloc(); }
+
+    _LIBCPP_HIDE_FROM_ABI
+    _Tp* __get_elem() _NOEXCEPT { return __storage_.__get_elem(); }
+
+private:
+    virtual void __on_zero_shared() _NOEXCEPT {
+#if _LIBCPP_STD_VER > 17
+        using _TpAlloc = typename __allocator_traits_rebind<_Alloc, _Tp>::type;
+        _TpAlloc __tmp(*__get_alloc());
+        allocator_traits<_TpAlloc>::destroy(__tmp, __get_elem());
+#else
+        __get_elem()->~_Tp();
+#endif
+    }
+
+    virtual void __on_zero_shared_weak() _NOEXCEPT {
+        using _ControlBlockAlloc = typename __allocator_traits_rebind<_Alloc, __shared_ptr_emplace>::type;
+        using _ControlBlockPointer = typename allocator_traits<_ControlBlockAlloc>::pointer;
+        _ControlBlockAlloc __tmp(*__get_alloc());
+        __storage_.~_Storage();
+        allocator_traits<_ControlBlockAlloc>::deallocate(__tmp,
+            pointer_traits<_ControlBlockPointer>::pointer_to(*this), 1);
+    }
+
+    // This class implements the control block for non-array shared pointers created
+    // through `std::allocate_shared` and `std::make_shared`.
+    //
+    // In previous versions of the library, we used a compressed pair to store
+    // both the _Alloc and the _Tp. This implies using EBO, which is incompatible
+    // with Allocator construction for _Tp. To allow implementing P0674 in C++20,
+    // we now use a properly aligned char buffer while making sure that we maintain
+    // the same layout that we had when we used a compressed pair.
+    using _CompressedPair = __compressed_pair<_Alloc, _Tp>;
+    struct _ALIGNAS_TYPE(_CompressedPair) _Storage {
+        char __blob_[sizeof(_CompressedPair)];
+
+        _LIBCPP_HIDE_FROM_ABI explicit _Storage(_Alloc&& __a) {
+            ::new ((void*)__get_alloc()) _Alloc(_VSTD::move(__a));
+        }
+        _LIBCPP_HIDE_FROM_ABI ~_Storage() {
+            __get_alloc()->~_Alloc();
+        }
+        _Alloc* __get_alloc() _NOEXCEPT {
+            _CompressedPair *__as_pair = reinterpret_cast<_CompressedPair*>(__blob_);
+            typename _CompressedPair::_Base1* __first = _CompressedPair::__get_first_base(__as_pair);
+            _Alloc *__alloc = reinterpret_cast<_Alloc*>(__first);
+            return __alloc;
+        }
+        _LIBCPP_NO_CFI _Tp* __get_elem() _NOEXCEPT {
+            _CompressedPair *__as_pair = reinterpret_cast<_CompressedPair*>(__blob_);
+            typename _CompressedPair::_Base2* __second = _CompressedPair::__get_second_base(__as_pair);
+            _Tp *__elem = reinterpret_cast<_Tp*>(__second);
+            return __elem;
+        }
+    };
+
+    static_assert(_LIBCPP_ALIGNOF(_Storage) == _LIBCPP_ALIGNOF(_CompressedPair), "");
+    static_assert(sizeof(_Storage) == sizeof(_CompressedPair), "");
+    _Storage __storage_;
+};
+
+struct __shared_ptr_dummy_rebind_allocator_type;
+template <>
+class _LIBCPP_TEMPLATE_VIS allocator<__shared_ptr_dummy_rebind_allocator_type>
+{
+public:
+    template <class _Other>
+    struct rebind
+    {
+        typedef allocator<_Other> other;
+    };
+};
+
+template<class _Tp> class _LIBCPP_TEMPLATE_VIS enable_shared_from_this;
+
+template<class _Tp, class _Up>
+struct __compatible_with
+#if _LIBCPP_STD_VER > 14
+    : is_convertible<remove_extent_t<_Tp>*, remove_extent_t<_Up>*> {};
+#else
+    : is_convertible<_Tp*, _Up*> {};
+#endif // _LIBCPP_STD_VER > 14
+
+template <class _Dp, class _Pt,
+    class = decltype(_VSTD::declval<_Dp>()(_VSTD::declval<_Pt>()))>
+static true_type __well_formed_deleter_test(int);
+
+template <class, class>
+static false_type __well_formed_deleter_test(...);
+
+template <class _Dp, class _Pt>
+struct __well_formed_deleter : decltype(__well_formed_deleter_test<_Dp, _Pt>(0)) {};
+
+template<class _Dp, class _Tp, class _Yp>
+struct __shared_ptr_deleter_ctor_reqs
+{
+    static const bool value = __compatible_with<_Tp, _Yp>::value &&
+                              is_move_constructible<_Dp>::value &&
+                              __well_formed_deleter<_Dp, _Tp*>::value;
+};
+
+#if defined(_LIBCPP_ABI_ENABLE_SHARED_PTR_TRIVIAL_ABI)
+#  define _LIBCPP_SHARED_PTR_TRIVIAL_ABI __attribute__((trivial_abi))
+#else
+#  define _LIBCPP_SHARED_PTR_TRIVIAL_ABI
+#endif
+
+template<class _Tp>
+class _LIBCPP_SHARED_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS shared_ptr
+{
+public:
+#if _LIBCPP_STD_VER > 14
+    typedef weak_ptr<_Tp> weak_type;
+    typedef remove_extent_t<_Tp> element_type;
+#else
+    typedef _Tp element_type;
+#endif
+
+private:
+    element_type*      __ptr_;
+    __shared_weak_count* __cntrl_;
+
+    struct __nat {int __for_bool_;};
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_CONSTEXPR shared_ptr() _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_CONSTEXPR shared_ptr(nullptr_t) _NOEXCEPT;
+    template<class _Yp>
+        explicit shared_ptr(_Yp* __p,
+                            typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type = __nat());
+    template<class _Yp, class _Dp>
+        shared_ptr(_Yp* __p, _Dp __d,
+                   typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type = __nat());
+    template<class _Yp, class _Dp, class _Alloc>
+        shared_ptr(_Yp* __p, _Dp __d, _Alloc __a,
+                   typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type = __nat());
+    template <class _Dp> shared_ptr(nullptr_t __p, _Dp __d);
+    template <class _Dp, class _Alloc> shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a);
+    template<class _Yp> _LIBCPP_INLINE_VISIBILITY shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    shared_ptr(const shared_ptr& __r) _NOEXCEPT;
+    template<class _Yp>
+        _LIBCPP_INLINE_VISIBILITY
+        shared_ptr(const shared_ptr<_Yp>& __r,
+                   typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type = __nat())
+                       _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    shared_ptr(shared_ptr&& __r) _NOEXCEPT;
+    template<class _Yp> _LIBCPP_INLINE_VISIBILITY  shared_ptr(shared_ptr<_Yp>&& __r,
+                   typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type = __nat())
+                       _NOEXCEPT;
+    template<class _Yp> explicit shared_ptr(const weak_ptr<_Yp>& __r,
+                   typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type= __nat());
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
+    template<class _Yp>
+        shared_ptr(auto_ptr<_Yp>&& __r,
+                   typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type = __nat());
+#endif
+    template <class _Yp, class _Dp>
+        shared_ptr(unique_ptr<_Yp, _Dp>&&,
+                   typename enable_if
+                   <
+                       !is_lvalue_reference<_Dp>::value &&
+                       is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
+                       __nat
+                   >::type = __nat());
+    template <class _Yp, class _Dp>
+        shared_ptr(unique_ptr<_Yp, _Dp>&&,
+                   typename enable_if
+                   <
+                       is_lvalue_reference<_Dp>::value &&
+                       is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
+                       __nat
+                   >::type = __nat());
+
+    ~shared_ptr();
+
+    _LIBCPP_INLINE_VISIBILITY
+    shared_ptr& operator=(const shared_ptr& __r) _NOEXCEPT;
+    template<class _Yp>
+        typename enable_if
+        <
+            __compatible_with<_Yp, element_type>::value,
+            shared_ptr&
+        >::type
+        _LIBCPP_INLINE_VISIBILITY
+        operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    shared_ptr& operator=(shared_ptr&& __r) _NOEXCEPT;
+    template<class _Yp>
+        typename enable_if
+        <
+            __compatible_with<_Yp, element_type>::value,
+            shared_ptr&
+        >::type
+        _LIBCPP_INLINE_VISIBILITY
+        operator=(shared_ptr<_Yp>&& __r);
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
+    template<class _Yp>
+        _LIBCPP_INLINE_VISIBILITY
+        typename enable_if
+        <
+            !is_array<_Yp>::value &&
+            is_convertible<_Yp*, element_type*>::value,
+            shared_ptr
+        >::type&
+        operator=(auto_ptr<_Yp>&& __r);
+#endif
+    template <class _Yp, class _Dp>
+        typename enable_if
+        <
+            is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
+            shared_ptr&
+        >::type
+        _LIBCPP_INLINE_VISIBILITY
+        operator=(unique_ptr<_Yp, _Dp>&& __r);
+
+    _LIBCPP_INLINE_VISIBILITY
+    void swap(shared_ptr& __r) _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    void reset() _NOEXCEPT;
+    template<class _Yp>
+        typename enable_if
+        <
+            __compatible_with<_Yp, element_type>::value,
+            void
+        >::type
+        _LIBCPP_INLINE_VISIBILITY
+        reset(_Yp* __p);
+    template<class _Yp, class _Dp>
+        typename enable_if
+        <
+            __compatible_with<_Yp, element_type>::value,
+            void
+        >::type
+        _LIBCPP_INLINE_VISIBILITY
+        reset(_Yp* __p, _Dp __d);
+    template<class _Yp, class _Dp, class _Alloc>
+        typename enable_if
+        <
+            __compatible_with<_Yp, element_type>::value,
+            void
+        >::type
+        _LIBCPP_INLINE_VISIBILITY
+        reset(_Yp* __p, _Dp __d, _Alloc __a);
+
+    _LIBCPP_INLINE_VISIBILITY
+    element_type* get() const _NOEXCEPT {return __ptr_;}
+    _LIBCPP_INLINE_VISIBILITY
+    typename add_lvalue_reference<element_type>::type operator*() const _NOEXCEPT
+        {return *__ptr_;}
+    _LIBCPP_INLINE_VISIBILITY
+    element_type* operator->() const _NOEXCEPT
+    {
+        static_assert(!_VSTD::is_array<_Tp>::value,
+                      "std::shared_ptr<T>::operator-> is only valid when T is not an array type.");
+        return __ptr_;
+    }
+    _LIBCPP_INLINE_VISIBILITY
+    long use_count() const _NOEXCEPT {return __cntrl_ ? __cntrl_->use_count() : 0;}
+    _LIBCPP_INLINE_VISIBILITY
+    bool unique() const _NOEXCEPT {return use_count() == 1;}
+    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT {return get() != nullptr;}
+    template <class _Up>
+        _LIBCPP_INLINE_VISIBILITY
+        bool owner_before(shared_ptr<_Up> const& __p) const _NOEXCEPT
+        {return __cntrl_ < __p.__cntrl_;}
+    template <class _Up>
+        _LIBCPP_INLINE_VISIBILITY
+        bool owner_before(weak_ptr<_Up> const& __p) const _NOEXCEPT
+        {return __cntrl_ < __p.__cntrl_;}
+    _LIBCPP_INLINE_VISIBILITY
+    bool
+    __owner_equivalent(const shared_ptr& __p) const
+        {return __cntrl_ == __p.__cntrl_;}
+
+#if _LIBCPP_STD_VER > 14
+    typename add_lvalue_reference<element_type>::type
+    _LIBCPP_INLINE_VISIBILITY
+    operator[](ptrdiff_t __i) const
+    {
+            static_assert(_VSTD::is_array<_Tp>::value,
+                          "std::shared_ptr<T>::operator[] is only valid when T is an array type.");
+            return __ptr_[__i];
+    }
+#endif
+
+#ifndef _LIBCPP_NO_RTTI
+    template <class _Dp>
+        _LIBCPP_INLINE_VISIBILITY
+        _Dp* __get_deleter() const _NOEXCEPT
+            {return static_cast<_Dp*>(__cntrl_
+                    ? const_cast<void *>(__cntrl_->__get_deleter(typeid(_Dp)))
+                      : nullptr);}
+#endif  // _LIBCPP_NO_RTTI
+
+    template<class _Yp, class _CntrlBlk>
+    static shared_ptr<_Tp>
+    __create_with_control_block(_Yp* __p, _CntrlBlk* __cntrl) _NOEXCEPT
+    {
+        shared_ptr<_Tp> __r;
+        __r.__ptr_ = __p;
+        __r.__cntrl_ = __cntrl;
+        __r.__enable_weak_this(__r.__ptr_, __r.__ptr_);
+        return __r;
+    }
+
+private:
+    template <class _Yp, bool = is_function<_Yp>::value>
+        struct __shared_ptr_default_allocator
+        {
+            typedef allocator<_Yp> type;
+        };
+
+    template <class _Yp>
+        struct __shared_ptr_default_allocator<_Yp, true>
+        {
+            typedef allocator<__shared_ptr_dummy_rebind_allocator_type> type;
+        };
+
+    template <class _Yp, class _OrigPtr>
+        _LIBCPP_INLINE_VISIBILITY
+        typename enable_if<is_convertible<_OrigPtr*,
+                                          const enable_shared_from_this<_Yp>*
+        >::value,
+            void>::type
+        __enable_weak_this(const enable_shared_from_this<_Yp>* __e,
+                           _OrigPtr* __ptr) _NOEXCEPT
+        {
+            typedef typename remove_cv<_Yp>::type _RawYp;
+            if (__e && __e->__weak_this_.expired())
+            {
+                __e->__weak_this_ = shared_ptr<_RawYp>(*this,
+                    const_cast<_RawYp*>(static_cast<const _Yp*>(__ptr)));
+            }
+        }
+
+    _LIBCPP_INLINE_VISIBILITY void __enable_weak_this(...) _NOEXCEPT {}
+
+    template <class, class _Yp>
+        struct __shared_ptr_default_delete
+            : default_delete<_Yp> {};
+
+    template <class _Yp, class _Un, size_t _Sz>
+        struct __shared_ptr_default_delete<_Yp[_Sz], _Un>
+            : default_delete<_Yp[]> {};
+
+    template <class _Yp, class _Un>
+        struct __shared_ptr_default_delete<_Yp[], _Un>
+            : default_delete<_Yp[]> {};
+
+    template <class _Up> friend class _LIBCPP_TEMPLATE_VIS shared_ptr;
+    template <class _Up> friend class _LIBCPP_TEMPLATE_VIS weak_ptr;
+};
+
+#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
+template<class _Tp>
+shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>;
+template<class _Tp, class _Dp>
+shared_ptr(unique_ptr<_Tp, _Dp>) -> shared_ptr<_Tp>;
+#endif
+
+template<class _Tp>
+inline
+_LIBCPP_CONSTEXPR
+shared_ptr<_Tp>::shared_ptr() _NOEXCEPT
+    : __ptr_(nullptr),
+      __cntrl_(nullptr)
+{
+}
+
+template<class _Tp>
+inline
+_LIBCPP_CONSTEXPR
+shared_ptr<_Tp>::shared_ptr(nullptr_t) _NOEXCEPT
+    : __ptr_(nullptr),
+      __cntrl_(nullptr)
+{
+}
+
+template<class _Tp>
+template<class _Yp>
+shared_ptr<_Tp>::shared_ptr(_Yp* __p,
+                            typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type)
+    : __ptr_(__p)
+{
+    unique_ptr<_Yp> __hold(__p);
+    typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
+    typedef __shared_ptr_pointer<_Yp*, __shared_ptr_default_delete<_Tp, _Yp>, _AllocT > _CntrlBlk;
+    __cntrl_ = new _CntrlBlk(__p, __shared_ptr_default_delete<_Tp, _Yp>(), _AllocT());
+    __hold.release();
+    __enable_weak_this(__p, __p);
+}
+
+template<class _Tp>
+template<class _Yp, class _Dp>
+shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d,
+                            typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type)
+    : __ptr_(__p)
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
+        typedef __shared_ptr_pointer<_Yp*, _Dp, _AllocT > _CntrlBlk;
+#ifndef _LIBCPP_CXX03_LANG
+        __cntrl_ = new _CntrlBlk(__p, _VSTD::move(__d), _AllocT());
+#else
+        __cntrl_ = new _CntrlBlk(__p, __d, _AllocT());
+#endif // not _LIBCPP_CXX03_LANG
+        __enable_weak_this(__p, __p);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        __d(__p);
+        throw;
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+template<class _Tp>
+template<class _Dp>
+shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d)
+    : __ptr_(nullptr)
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        typedef typename __shared_ptr_default_allocator<_Tp>::type _AllocT;
+        typedef __shared_ptr_pointer<nullptr_t, _Dp, _AllocT > _CntrlBlk;
+#ifndef _LIBCPP_CXX03_LANG
+        __cntrl_ = new _CntrlBlk(__p, _VSTD::move(__d), _AllocT());
+#else
+        __cntrl_ = new _CntrlBlk(__p, __d, _AllocT());
+#endif // not _LIBCPP_CXX03_LANG
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        __d(__p);
+        throw;
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+template<class _Tp>
+template<class _Yp, class _Dp, class _Alloc>
+shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d, _Alloc __a,
+                            typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type)
+    : __ptr_(__p)
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        typedef __shared_ptr_pointer<_Yp*, _Dp, _Alloc> _CntrlBlk;
+        typedef typename __allocator_traits_rebind<_Alloc, _CntrlBlk>::type _A2;
+        typedef __allocator_destructor<_A2> _D2;
+        _A2 __a2(__a);
+        unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
+        ::new ((void*)_VSTD::addressof(*__hold2.get()))
+#ifndef _LIBCPP_CXX03_LANG
+            _CntrlBlk(__p, _VSTD::move(__d), __a);
+#else
+            _CntrlBlk(__p, __d, __a);
+#endif // not _LIBCPP_CXX03_LANG
+        __cntrl_ = _VSTD::addressof(*__hold2.release());
+        __enable_weak_this(__p, __p);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        __d(__p);
+        throw;
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+template<class _Tp>
+template<class _Dp, class _Alloc>
+shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a)
+    : __ptr_(nullptr)
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+        typedef __shared_ptr_pointer<nullptr_t, _Dp, _Alloc> _CntrlBlk;
+        typedef typename __allocator_traits_rebind<_Alloc, _CntrlBlk>::type _A2;
+        typedef __allocator_destructor<_A2> _D2;
+        _A2 __a2(__a);
+        unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
+        ::new ((void*)_VSTD::addressof(*__hold2.get()))
+#ifndef _LIBCPP_CXX03_LANG
+            _CntrlBlk(__p, _VSTD::move(__d), __a);
+#else
+            _CntrlBlk(__p, __d, __a);
+#endif // not _LIBCPP_CXX03_LANG
+        __cntrl_ = _VSTD::addressof(*__hold2.release());
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        __d(__p);
+        throw;
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+template<class _Tp>
+template<class _Yp>
+inline
+shared_ptr<_Tp>::shared_ptr(const shared_ptr<_Yp>& __r, element_type *__p) _NOEXCEPT
+    : __ptr_(__p),
+      __cntrl_(__r.__cntrl_)
+{
+    if (__cntrl_)
+        __cntrl_->__add_shared();
+}
+
+template<class _Tp>
+inline
+shared_ptr<_Tp>::shared_ptr(const shared_ptr& __r) _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    if (__cntrl_)
+        __cntrl_->__add_shared();
+}
+
+template<class _Tp>
+template<class _Yp>
+inline
+shared_ptr<_Tp>::shared_ptr(const shared_ptr<_Yp>& __r,
+                            typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type)
+         _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    if (__cntrl_)
+        __cntrl_->__add_shared();
+}
+
+template<class _Tp>
+inline
+shared_ptr<_Tp>::shared_ptr(shared_ptr&& __r) _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    __r.__ptr_ = nullptr;
+    __r.__cntrl_ = nullptr;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline
+shared_ptr<_Tp>::shared_ptr(shared_ptr<_Yp>&& __r,
+                            typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type)
+         _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    __r.__ptr_ = nullptr;
+    __r.__cntrl_ = nullptr;
+}
+
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
+template<class _Tp>
+template<class _Yp>
+shared_ptr<_Tp>::shared_ptr(auto_ptr<_Yp>&& __r,
+                            typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type)
+    : __ptr_(__r.get())
+{
+    typedef __shared_ptr_pointer<_Yp*, default_delete<_Yp>, allocator<_Yp> > _CntrlBlk;
+    __cntrl_ = new _CntrlBlk(__r.get(), default_delete<_Yp>(), allocator<_Yp>());
+    __enable_weak_this(__r.get(), __r.get());
+    __r.release();
+}
+#endif
+
+template<class _Tp>
+template <class _Yp, class _Dp>
+shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp>&& __r,
+                            typename enable_if
+                            <
+                                !is_lvalue_reference<_Dp>::value &&
+                                is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
+                                __nat
+                            >::type)
+    : __ptr_(__r.get())
+{
+#if _LIBCPP_STD_VER > 11
+    if (__ptr_ == nullptr)
+        __cntrl_ = nullptr;
+    else
+#endif
+    {
+        typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
+        typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer, _Dp, _AllocT > _CntrlBlk;
+        __cntrl_ = new _CntrlBlk(__r.get(), __r.get_deleter(), _AllocT());
+        __enable_weak_this(__r.get(), __r.get());
+    }
+    __r.release();
+}
+
+template<class _Tp>
+template <class _Yp, class _Dp>
+shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp>&& __r,
+                            typename enable_if
+                            <
+                                is_lvalue_reference<_Dp>::value &&
+                                is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
+                                __nat
+                            >::type)
+    : __ptr_(__r.get())
+{
+#if _LIBCPP_STD_VER > 11
+    if (__ptr_ == nullptr)
+        __cntrl_ = nullptr;
+    else
+#endif
+    {
+        typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
+        typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer,
+                                     reference_wrapper<typename remove_reference<_Dp>::type>,
+                                     _AllocT > _CntrlBlk;
+        __cntrl_ = new _CntrlBlk(__r.get(), _VSTD::ref(__r.get_deleter()), _AllocT());
+        __enable_weak_this(__r.get(), __r.get());
+    }
+    __r.release();
+}
+
+template<class _Tp>
+shared_ptr<_Tp>::~shared_ptr()
+{
+    if (__cntrl_)
+        __cntrl_->__release_shared();
+}
+
+template<class _Tp>
+inline
+shared_ptr<_Tp>&
+shared_ptr<_Tp>::operator=(const shared_ptr& __r) _NOEXCEPT
+{
+    shared_ptr(__r).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline
+typename enable_if
+<
+    __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
+    shared_ptr<_Tp>&
+>::type
+shared_ptr<_Tp>::operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT
+{
+    shared_ptr(__r).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+inline
+shared_ptr<_Tp>&
+shared_ptr<_Tp>::operator=(shared_ptr&& __r) _NOEXCEPT
+{
+    shared_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline
+typename enable_if
+<
+    __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
+    shared_ptr<_Tp>&
+>::type
+shared_ptr<_Tp>::operator=(shared_ptr<_Yp>&& __r)
+{
+    shared_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
+template<class _Tp>
+template<class _Yp>
+inline
+typename enable_if
+<
+    !is_array<_Yp>::value &&
+    is_convertible<_Yp*, typename shared_ptr<_Tp>::element_type*>::value,
+    shared_ptr<_Tp>
+>::type&
+shared_ptr<_Tp>::operator=(auto_ptr<_Yp>&& __r)
+{
+    shared_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+#endif
+
+template<class _Tp>
+template <class _Yp, class _Dp>
+inline
+typename enable_if
+<
+    is_convertible<typename unique_ptr<_Yp, _Dp>::pointer,
+                   typename shared_ptr<_Tp>::element_type*>::value,
+    shared_ptr<_Tp>&
+>::type
+shared_ptr<_Tp>::operator=(unique_ptr<_Yp, _Dp>&& __r)
+{
+    shared_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+inline
+void
+shared_ptr<_Tp>::swap(shared_ptr& __r) _NOEXCEPT
+{
+    _VSTD::swap(__ptr_, __r.__ptr_);
+    _VSTD::swap(__cntrl_, __r.__cntrl_);
+}
+
+template<class _Tp>
+inline
+void
+shared_ptr<_Tp>::reset() _NOEXCEPT
+{
+    shared_ptr().swap(*this);
+}
+
+template<class _Tp>
+template<class _Yp>
+inline
+typename enable_if
+<
+    __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
+    void
+>::type
+shared_ptr<_Tp>::reset(_Yp* __p)
+{
+    shared_ptr(__p).swap(*this);
+}
+
+template<class _Tp>
+template<class _Yp, class _Dp>
+inline
+typename enable_if
+<
+    __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
+    void
+>::type
+shared_ptr<_Tp>::reset(_Yp* __p, _Dp __d)
+{
+    shared_ptr(__p, __d).swap(*this);
+}
+
+template<class _Tp>
+template<class _Yp, class _Dp, class _Alloc>
+inline
+typename enable_if
+<
+    __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
+    void
+>::type
+shared_ptr<_Tp>::reset(_Yp* __p, _Dp __d, _Alloc __a)
+{
+    shared_ptr(__p, __d, __a).swap(*this);
+}
+
+//
+// std::allocate_shared and std::make_shared
+//
+template<class _Tp, class _Alloc, class ..._Args, class = _EnableIf<!is_array<_Tp>::value> >
+_LIBCPP_HIDE_FROM_ABI
+shared_ptr<_Tp> allocate_shared(const _Alloc& __a, _Args&& ...__args)
+{
+    using _ControlBlock = __shared_ptr_emplace<_Tp, _Alloc>;
+    using _ControlBlockAllocator = typename __allocator_traits_rebind<_Alloc, _ControlBlock>::type;
+    __allocation_guard<_ControlBlockAllocator> __guard(__a, 1);
+    ::new ((void*)_VSTD::addressof(*__guard.__get())) _ControlBlock(__a, _VSTD::forward<_Args>(__args)...);
+    auto __control_block = __guard.__release_ptr();
+    return shared_ptr<_Tp>::__create_with_control_block((*__control_block).__get_elem(), _VSTD::addressof(*__control_block));
+}
+
+template<class _Tp, class ..._Args, class = _EnableIf<!is_array<_Tp>::value> >
+_LIBCPP_HIDE_FROM_ABI
+shared_ptr<_Tp> make_shared(_Args&& ...__args)
+{
+    return _VSTD::allocate_shared<_Tp>(allocator<_Tp>(), _VSTD::forward<_Args>(__args)...);
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
+{
+    return __x.get() == __y.get();
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
+{
+    return !(__x == __y);
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
+{
+#if _LIBCPP_STD_VER <= 11
+    typedef typename common_type<_Tp*, _Up*>::type _Vp;
+    return less<_Vp>()(__x.get(), __y.get());
+#else
+    return less<>()(__x.get(), __y.get());
+#endif
+
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
+{
+    return __y < __x;
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<=(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
+{
+    return !(__y < __x);
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>=(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
+{
+    return !(__x < __y);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
+{
+    return !__x;
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
+{
+    return !__x;
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
+{
+    return static_cast<bool>(__x);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
+{
+    return static_cast<bool>(__x);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
+{
+    return less<_Tp*>()(__x.get(), nullptr);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
+{
+    return less<_Tp*>()(nullptr, __x.get());
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
+{
+    return nullptr < __x;
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
+{
+    return __x < nullptr;
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<=(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
+{
+    return !(nullptr < __x);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<=(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
+{
+    return !(__x < nullptr);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>=(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
+{
+    return !(__x < nullptr);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>=(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
+{
+    return !(nullptr < __x);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+swap(shared_ptr<_Tp>& __x, shared_ptr<_Tp>& __y) _NOEXCEPT
+{
+    __x.swap(__y);
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>
+static_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
+{
+    return shared_ptr<_Tp>(__r,
+                           static_cast<
+                               typename shared_ptr<_Tp>::element_type*>(__r.get()));
+}
+
+template<class _Tp, class _Up>
+inline _LIBCPP_INLINE_VISIBILITY
+shared_ptr<_Tp>
+dynamic_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
+{
+    typedef typename shared_ptr<_Tp>::element_type _ET;
+    _ET* __p = dynamic_cast<_ET*>(__r.get());
+    return __p ? shared_ptr<_Tp>(__r, __p) : shared_ptr<_Tp>();
+}
+
+template<class _Tp, class _Up>
+shared_ptr<_Tp>
+const_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
+{
+    typedef typename shared_ptr<_Tp>::element_type _RTp;
+    return shared_ptr<_Tp>(__r, const_cast<_RTp*>(__r.get()));
+}
+
+template<class _Tp, class _Up>
+shared_ptr<_Tp>
+reinterpret_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
+{
+    return shared_ptr<_Tp>(__r,
+                           reinterpret_cast<
+                               typename shared_ptr<_Tp>::element_type*>(__r.get()));
+}
+
+#ifndef _LIBCPP_NO_RTTI
+
+template<class _Dp, class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_Dp*
+get_deleter(const shared_ptr<_Tp>& __p) _NOEXCEPT
+{
+    return __p.template __get_deleter<_Dp>();
+}
+
+#endif  // _LIBCPP_NO_RTTI
+
+template<class _Tp>
+class _LIBCPP_SHARED_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS weak_ptr
+{
+public:
+    typedef _Tp element_type;
+private:
+    element_type*        __ptr_;
+    __shared_weak_count* __cntrl_;
+
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_CONSTEXPR weak_ptr() _NOEXCEPT;
+    template<class _Yp> _LIBCPP_INLINE_VISIBILITY weak_ptr(shared_ptr<_Yp> const& __r,
+                   typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type = 0)
+                        _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    weak_ptr(weak_ptr const& __r) _NOEXCEPT;
+    template<class _Yp> _LIBCPP_INLINE_VISIBILITY weak_ptr(weak_ptr<_Yp> const& __r,
+                   typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type = 0)
+                         _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY
+    weak_ptr(weak_ptr&& __r) _NOEXCEPT;
+    template<class _Yp> _LIBCPP_INLINE_VISIBILITY weak_ptr(weak_ptr<_Yp>&& __r,
+                   typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type = 0)
+                         _NOEXCEPT;
+    ~weak_ptr();
+
+    _LIBCPP_INLINE_VISIBILITY
+    weak_ptr& operator=(weak_ptr const& __r) _NOEXCEPT;
+    template<class _Yp>
+        typename enable_if
+        <
+            is_convertible<_Yp*, element_type*>::value,
+            weak_ptr&
+        >::type
+        _LIBCPP_INLINE_VISIBILITY
+        operator=(weak_ptr<_Yp> const& __r) _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY
+    weak_ptr& operator=(weak_ptr&& __r) _NOEXCEPT;
+    template<class _Yp>
+        typename enable_if
+        <
+            is_convertible<_Yp*, element_type*>::value,
+            weak_ptr&
+        >::type
+        _LIBCPP_INLINE_VISIBILITY
+        operator=(weak_ptr<_Yp>&& __r) _NOEXCEPT;
+
+    template<class _Yp>
+        typename enable_if
+        <
+            is_convertible<_Yp*, element_type*>::value,
+            weak_ptr&
+        >::type
+        _LIBCPP_INLINE_VISIBILITY
+        operator=(shared_ptr<_Yp> const& __r) _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY
+    void swap(weak_ptr& __r) _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    void reset() _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY
+    long use_count() const _NOEXCEPT
+        {return __cntrl_ ? __cntrl_->use_count() : 0;}
+    _LIBCPP_INLINE_VISIBILITY
+    bool expired() const _NOEXCEPT
+        {return __cntrl_ == nullptr || __cntrl_->use_count() == 0;}
+    shared_ptr<_Tp> lock() const _NOEXCEPT;
+    template<class _Up>
+        _LIBCPP_INLINE_VISIBILITY
+        bool owner_before(const shared_ptr<_Up>& __r) const _NOEXCEPT
+        {return __cntrl_ < __r.__cntrl_;}
+    template<class _Up>
+        _LIBCPP_INLINE_VISIBILITY
+        bool owner_before(const weak_ptr<_Up>& __r) const _NOEXCEPT
+        {return __cntrl_ < __r.__cntrl_;}
+
+    template <class _Up> friend class _LIBCPP_TEMPLATE_VIS weak_ptr;
+    template <class _Up> friend class _LIBCPP_TEMPLATE_VIS shared_ptr;
+};
+
+#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
+template<class _Tp>
+weak_ptr(shared_ptr<_Tp>) -> weak_ptr<_Tp>;
+#endif
+
+template<class _Tp>
+inline
+_LIBCPP_CONSTEXPR
+weak_ptr<_Tp>::weak_ptr() _NOEXCEPT
+    : __ptr_(nullptr),
+      __cntrl_(nullptr)
+{
+}
+
+template<class _Tp>
+inline
+weak_ptr<_Tp>::weak_ptr(weak_ptr const& __r) _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    if (__cntrl_)
+        __cntrl_->__add_weak();
+}
+
+template<class _Tp>
+template<class _Yp>
+inline
+weak_ptr<_Tp>::weak_ptr(shared_ptr<_Yp> const& __r,
+                        typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type)
+                         _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    if (__cntrl_)
+        __cntrl_->__add_weak();
+}
+
+template<class _Tp>
+template<class _Yp>
+inline
+weak_ptr<_Tp>::weak_ptr(weak_ptr<_Yp> const& __r,
+                        typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type)
+         _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    if (__cntrl_)
+        __cntrl_->__add_weak();
+}
+
+template<class _Tp>
+inline
+weak_ptr<_Tp>::weak_ptr(weak_ptr&& __r) _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    __r.__ptr_ = nullptr;
+    __r.__cntrl_ = nullptr;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline
+weak_ptr<_Tp>::weak_ptr(weak_ptr<_Yp>&& __r,
+                        typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type)
+         _NOEXCEPT
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_)
+{
+    __r.__ptr_ = nullptr;
+    __r.__cntrl_ = nullptr;
+}
+
+template<class _Tp>
+weak_ptr<_Tp>::~weak_ptr()
+{
+    if (__cntrl_)
+        __cntrl_->__release_weak();
+}
+
+template<class _Tp>
+inline
+weak_ptr<_Tp>&
+weak_ptr<_Tp>::operator=(weak_ptr const& __r) _NOEXCEPT
+{
+    weak_ptr(__r).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline
+typename enable_if
+<
+    is_convertible<_Yp*, _Tp*>::value,
+    weak_ptr<_Tp>&
+>::type
+weak_ptr<_Tp>::operator=(weak_ptr<_Yp> const& __r) _NOEXCEPT
+{
+    weak_ptr(__r).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+inline
+weak_ptr<_Tp>&
+weak_ptr<_Tp>::operator=(weak_ptr&& __r) _NOEXCEPT
+{
+    weak_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline
+typename enable_if
+<
+    is_convertible<_Yp*, _Tp*>::value,
+    weak_ptr<_Tp>&
+>::type
+weak_ptr<_Tp>::operator=(weak_ptr<_Yp>&& __r) _NOEXCEPT
+{
+    weak_ptr(_VSTD::move(__r)).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+template<class _Yp>
+inline
+typename enable_if
+<
+    is_convertible<_Yp*, _Tp*>::value,
+    weak_ptr<_Tp>&
+>::type
+weak_ptr<_Tp>::operator=(shared_ptr<_Yp> const& __r) _NOEXCEPT
+{
+    weak_ptr(__r).swap(*this);
+    return *this;
+}
+
+template<class _Tp>
+inline
+void
+weak_ptr<_Tp>::swap(weak_ptr& __r) _NOEXCEPT
+{
+    _VSTD::swap(__ptr_, __r.__ptr_);
+    _VSTD::swap(__cntrl_, __r.__cntrl_);
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+swap(weak_ptr<_Tp>& __x, weak_ptr<_Tp>& __y) _NOEXCEPT
+{
+    __x.swap(__y);
+}
+
+template<class _Tp>
+inline
+void
+weak_ptr<_Tp>::reset() _NOEXCEPT
+{
+    weak_ptr().swap(*this);
+}
+
+template<class _Tp>
+template<class _Yp>
+shared_ptr<_Tp>::shared_ptr(const weak_ptr<_Yp>& __r,
+                            typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type)
+    : __ptr_(__r.__ptr_),
+      __cntrl_(__r.__cntrl_ ? __r.__cntrl_->lock() : __r.__cntrl_)
+{
+    if (__cntrl_ == nullptr)
+        __throw_bad_weak_ptr();
+}
+
+template<class _Tp>
+shared_ptr<_Tp>
+weak_ptr<_Tp>::lock() const _NOEXCEPT
+{
+    shared_ptr<_Tp> __r;
+    __r.__cntrl_ = __cntrl_ ? __cntrl_->lock() : __cntrl_;
+    if (__r.__cntrl_)
+        __r.__ptr_ = __ptr_;
+    return __r;
+}
+
+#if _LIBCPP_STD_VER > 14
+template <class _Tp = void> struct owner_less;
+#else
+template <class _Tp> struct owner_less;
+#endif
+
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS owner_less<shared_ptr<_Tp> >
+    : binary_function<shared_ptr<_Tp>, shared_ptr<_Tp>, bool>
+{
+    typedef bool result_type;
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(shared_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const _NOEXCEPT
+        {return __x.owner_before(__y);}
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(shared_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const _NOEXCEPT
+        {return __x.owner_before(__y);}
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(  weak_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const _NOEXCEPT
+        {return __x.owner_before(__y);}
+};
+
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS owner_less<weak_ptr<_Tp> >
+    : binary_function<weak_ptr<_Tp>, weak_ptr<_Tp>, bool>
+{
+    typedef bool result_type;
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(  weak_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const _NOEXCEPT
+        {return __x.owner_before(__y);}
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(shared_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const _NOEXCEPT
+        {return __x.owner_before(__y);}
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(  weak_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const _NOEXCEPT
+        {return __x.owner_before(__y);}
+};
+
+#if _LIBCPP_STD_VER > 14
+template <>
+struct _LIBCPP_TEMPLATE_VIS owner_less<void>
+{
+    template <class _Tp, class _Up>
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()( shared_ptr<_Tp> const& __x, shared_ptr<_Up> const& __y) const _NOEXCEPT
+        {return __x.owner_before(__y);}
+    template <class _Tp, class _Up>
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()( shared_ptr<_Tp> const& __x,   weak_ptr<_Up> const& __y) const _NOEXCEPT
+        {return __x.owner_before(__y);}
+    template <class _Tp, class _Up>
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(   weak_ptr<_Tp> const& __x, shared_ptr<_Up> const& __y) const _NOEXCEPT
+        {return __x.owner_before(__y);}
+    template <class _Tp, class _Up>
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(   weak_ptr<_Tp> const& __x,   weak_ptr<_Up> const& __y) const _NOEXCEPT
+        {return __x.owner_before(__y);}
+    typedef void is_transparent;
+};
+#endif
+
+template<class _Tp>
+class _LIBCPP_TEMPLATE_VIS enable_shared_from_this
+{
+    mutable weak_ptr<_Tp> __weak_this_;
+protected:
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    enable_shared_from_this() _NOEXCEPT {}
+    _LIBCPP_INLINE_VISIBILITY
+    enable_shared_from_this(enable_shared_from_this const&) _NOEXCEPT {}
+    _LIBCPP_INLINE_VISIBILITY
+    enable_shared_from_this& operator=(enable_shared_from_this const&) _NOEXCEPT
+        {return *this;}
+    _LIBCPP_INLINE_VISIBILITY
+    ~enable_shared_from_this() {}
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    shared_ptr<_Tp> shared_from_this()
+        {return shared_ptr<_Tp>(__weak_this_);}
+    _LIBCPP_INLINE_VISIBILITY
+    shared_ptr<_Tp const> shared_from_this() const
+        {return shared_ptr<const _Tp>(__weak_this_);}
+
+#if _LIBCPP_STD_VER > 14
+    _LIBCPP_INLINE_VISIBILITY
+    weak_ptr<_Tp> weak_from_this() _NOEXCEPT
+       { return __weak_this_; }
+
+    _LIBCPP_INLINE_VISIBILITY
+    weak_ptr<const _Tp> weak_from_this() const _NOEXCEPT
+        { return __weak_this_; }
+#endif // _LIBCPP_STD_VER > 14
+
+    template <class _Up> friend class shared_ptr;
+};
+
+template <class _Tp> struct _LIBCPP_TEMPLATE_VIS hash;
+
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS hash<shared_ptr<_Tp> >
+{
+    typedef shared_ptr<_Tp>      argument_type;
+    typedef size_t               result_type;
+
+    _LIBCPP_INLINE_VISIBILITY
+    result_type operator()(const argument_type& __ptr) const _NOEXCEPT
+    {
+        return hash<typename shared_ptr<_Tp>::element_type*>()(__ptr.get());
+    }
+};
+
+template<class _CharT, class _Traits, class _Yp>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_ostream<_CharT, _Traits>&
+operator<<(basic_ostream<_CharT, _Traits>& __os, shared_ptr<_Yp> const& __p);
+
+
+#if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
+
+class _LIBCPP_TYPE_VIS __sp_mut
+{
+    void* __lx;
+public:
+    void lock() _NOEXCEPT;
+    void unlock() _NOEXCEPT;
+
+private:
+    _LIBCPP_CONSTEXPR __sp_mut(void*) _NOEXCEPT;
+    __sp_mut(const __sp_mut&);
+    __sp_mut& operator=(const __sp_mut&);
+
+    friend _LIBCPP_FUNC_VIS __sp_mut& __get_sp_mut(const void*);
+};
+
+_LIBCPP_FUNC_VIS _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
+__sp_mut& __get_sp_mut(const void*);
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+atomic_is_lock_free(const shared_ptr<_Tp>*)
+{
+    return false;
+}
+
+template <class _Tp>
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
+shared_ptr<_Tp>
+atomic_load(const shared_ptr<_Tp>* __p)
+{
+    __sp_mut& __m = __get_sp_mut(__p);
+    __m.lock();
+    shared_ptr<_Tp> __q = *__p;
+    __m.unlock();
+    return __q;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
+shared_ptr<_Tp>
+atomic_load_explicit(const shared_ptr<_Tp>* __p, memory_order)
+{
+    return atomic_load(__p);
+}
+
+template <class _Tp>
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
+void
+atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
+{
+    __sp_mut& __m = __get_sp_mut(__p);
+    __m.lock();
+    __p->swap(__r);
+    __m.unlock();
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
+void
+atomic_store_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order)
+{
+    atomic_store(__p, __r);
+}
+
+template <class _Tp>
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
+shared_ptr<_Tp>
+atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
+{
+    __sp_mut& __m = __get_sp_mut(__p);
+    __m.lock();
+    __p->swap(__r);
+    __m.unlock();
+    return __r;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
+shared_ptr<_Tp>
+atomic_exchange_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order)
+{
+    return atomic_exchange(__p, __r);
+}
+
+template <class _Tp>
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
+bool
+atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w)
+{
+    shared_ptr<_Tp> __temp;
+    __sp_mut& __m = __get_sp_mut(__p);
+    __m.lock();
+    if (__p->__owner_equivalent(*__v))
+    {
+        _VSTD::swap(__temp, *__p);
+        *__p = __w;
+        __m.unlock();
+        return true;
+    }
+    _VSTD::swap(__temp, *__v);
+    *__v = *__p;
+    __m.unlock();
+    return false;
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
+bool
+atomic_compare_exchange_weak(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w)
+{
+    return atomic_compare_exchange_strong(__p, __v, __w);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
+bool
+atomic_compare_exchange_strong_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v,
+                                        shared_ptr<_Tp> __w, memory_order, memory_order)
+{
+    return atomic_compare_exchange_strong(__p, __v, __w);
+}
+
+template <class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
+bool
+atomic_compare_exchange_weak_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v,
+                                      shared_ptr<_Tp> __w, memory_order, memory_order)
+{
+    return atomic_compare_exchange_weak(__p, __v, __w);
+}
+
+#endif  // !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif  // _LIBCPP___MEMORY_SHARED_PTR_H

libcxx/include/__memory/uninitialized.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_UNINITIALIZED_H
+#define _LIBCPP___MEMORY_UNINITIALIZED_H
+
+#include <__config>
+#include <__memory/base.h> // addressof, destroy_at
+#include <iterator>
+#include <utility>
+
+#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 _InputIterator, class _ForwardIterator>
+_ForwardIterator
+uninitialized_copy(_InputIterator __f, _InputIterator __l, _ForwardIterator __r)
+{
+    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    _ForwardIterator __s = __r;
+    try
+    {
+#endif
+        for (; __f != __l; ++__f, (void) ++__r)
+            ::new ((void*)_VSTD::addressof(*__r)) value_type(*__f);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        for (; __s != __r; ++__s)
+            __s->~value_type();
+        throw;
+    }
+#endif
+    return __r;
+}
+
+template <class _InputIterator, class _Size, class _ForwardIterator>
+_ForwardIterator
+uninitialized_copy_n(_InputIterator __f, _Size __n, _ForwardIterator __r)
+{
+    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    _ForwardIterator __s = __r;
+    try
+    {
+#endif
+        for (; __n > 0; ++__f, (void) ++__r, (void) --__n)
+            ::new ((void*)_VSTD::addressof(*__r)) value_type(*__f);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        for (; __s != __r; ++__s)
+            __s->~value_type();
+        throw;
+    }
+#endif
+    return __r;
+}
+
+template <class _ForwardIterator, class _Tp>
+void
+uninitialized_fill(_ForwardIterator __f, _ForwardIterator __l, const _Tp& __x)
+{
+    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    _ForwardIterator __s = __f;
+    try
+    {
+#endif
+        for (; __f != __l; ++__f)
+            ::new ((void*)_VSTD::addressof(*__f)) value_type(__x);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        for (; __s != __f; ++__s)
+            __s->~value_type();
+        throw;
+    }
+#endif
+}
+
+template <class _ForwardIterator, class _Size, class _Tp>
+_ForwardIterator
+uninitialized_fill_n(_ForwardIterator __f, _Size __n, const _Tp& __x)
+{
+    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    _ForwardIterator __s = __f;
+    try
+    {
+#endif
+        for (; __n > 0; ++__f, (void) --__n)
+            ::new ((void*)_VSTD::addressof(*__f)) value_type(__x);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        for (; __s != __f; ++__s)
+            __s->~value_type();
+        throw;
+    }
+#endif
+    return __f;
+}
+
+#if _LIBCPP_STD_VER > 14
+
+template <class _ForwardIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void destroy(_ForwardIterator __first, _ForwardIterator __last) {
+    for (; __first != __last; ++__first)
+        _VSTD::destroy_at(_VSTD::addressof(*__first));
+}
+
+template <class _ForwardIterator, class _Size>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_ForwardIterator destroy_n(_ForwardIterator __first, _Size __n) {
+    for (; __n > 0; (void)++__first, --__n)
+        _VSTD::destroy_at(_VSTD::addressof(*__first));
+    return __first;
+}
+
+template <class _ForwardIterator>
+inline _LIBCPP_INLINE_VISIBILITY
+void uninitialized_default_construct(_ForwardIterator __first, _ForwardIterator __last) {
+    using _Vt = typename iterator_traits<_ForwardIterator>::value_type;
+    auto __idx = __first;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try {
+#endif
+    for (; __idx != __last; ++__idx)
+        ::new ((void*)_VSTD::addressof(*__idx)) _Vt;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    } catch (...) {
+        _VSTD::destroy(__first, __idx);
+        throw;
+    }
+#endif
+}
+
+template <class _ForwardIterator, class _Size>
+inline _LIBCPP_INLINE_VISIBILITY
+_ForwardIterator uninitialized_default_construct_n(_ForwardIterator __first, _Size __n) {
+    using _Vt = typename iterator_traits<_ForwardIterator>::value_type;
+    auto __idx = __first;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try {
+#endif
+    for (; __n > 0; (void)++__idx, --__n)
+        ::new ((void*)_VSTD::addressof(*__idx)) _Vt;
+    return __idx;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    } catch (...) {
+        _VSTD::destroy(__first, __idx);
+        throw;
+    }
+#endif
+}
+
+
+template <class _ForwardIterator>
+inline _LIBCPP_INLINE_VISIBILITY
+void uninitialized_value_construct(_ForwardIterator __first, _ForwardIterator __last) {
+    using _Vt = typename iterator_traits<_ForwardIterator>::value_type;
+    auto __idx = __first;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try {
+#endif
+    for (; __idx != __last; ++__idx)
+        ::new ((void*)_VSTD::addressof(*__idx)) _Vt();
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    } catch (...) {
+        _VSTD::destroy(__first, __idx);
+        throw;
+    }
+#endif
+}
+
+template <class _ForwardIterator, class _Size>
+inline _LIBCPP_INLINE_VISIBILITY
+_ForwardIterator uninitialized_value_construct_n(_ForwardIterator __first, _Size __n) {
+    using _Vt = typename iterator_traits<_ForwardIterator>::value_type;
+    auto __idx = __first;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try {
+#endif
+    for (; __n > 0; (void)++__idx, --__n)
+        ::new ((void*)_VSTD::addressof(*__idx)) _Vt();
+    return __idx;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    } catch (...) {
+        _VSTD::destroy(__first, __idx);
+        throw;
+    }
+#endif
+}
+
+
+template <class _InputIt, class _ForwardIt>
+inline _LIBCPP_INLINE_VISIBILITY
+_ForwardIt uninitialized_move(_InputIt __first, _InputIt __last, _ForwardIt __first_res) {
+    using _Vt = typename iterator_traits<_ForwardIt>::value_type;
+    auto __idx = __first_res;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try {
+#endif
+    for (; __first != __last; (void)++__idx, ++__first)
+        ::new ((void*)_VSTD::addressof(*__idx)) _Vt(_VSTD::move(*__first));
+    return __idx;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    } catch (...) {
+        _VSTD::destroy(__first_res, __idx);
+        throw;
+    }
+#endif
+}
+
+template <class _InputIt, class _Size, class _ForwardIt>
+inline _LIBCPP_INLINE_VISIBILITY
+pair<_InputIt, _ForwardIt>
+uninitialized_move_n(_InputIt __first, _Size __n, _ForwardIt __first_res) {
+    using _Vt = typename iterator_traits<_ForwardIt>::value_type;
+    auto __idx = __first_res;
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try {
+#endif
+    for (; __n > 0; ++__idx, (void)++__first, --__n)
+        ::new ((void*)_VSTD::addressof(*__idx)) _Vt(_VSTD::move(*__first));
+    return {__first, __idx};
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    } catch (...) {
+        _VSTD::destroy(__first_res, __idx);
+        throw;
+    }
+#endif
+}
+
+#endif // _LIBCPP_STD_VER > 14
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif  // _LIBCPP___MEMORY_UNINITIALIZED_H

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 <__config>
+#include <__functional_base> // std::less
+#include <__memory/allocator_traits.h> // __pointer
+#include <__memory/auto_ptr.h>
+#include <__memory/compressed_pair.h>
+#include <cstddef>
+#include <type_traits>
+#include <utility>
+
+#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 _LIBCPP_TEMPLATE_VIS default_delete {
+    static_assert(!is_function<_Tp>::value,
+                  "default_delete cannot be instantiated for function types");
+#ifndef _LIBCPP_CXX03_LANG
+  _LIBCPP_INLINE_VISIBILITY constexpr default_delete() _NOEXCEPT = default;
+#else
+  _LIBCPP_INLINE_VISIBILITY default_delete() {}
+#endif
+  template <class _Up>
+  _LIBCPP_INLINE_VISIBILITY
+  default_delete(const default_delete<_Up>&,
+                 typename enable_if<is_convertible<_Up*, _Tp*>::value>::type* =
+                     0) _NOEXCEPT {}
+
+  _LIBCPP_INLINE_VISIBILITY void operator()(_Tp* __ptr) const _NOEXCEPT {
+    static_assert(sizeof(_Tp) > 0,
+                  "default_delete can not delete incomplete type");
+    static_assert(!is_void<_Tp>::value,
+                  "default_delete can not delete incomplete type");
+    delete __ptr;
+  }
+};
+
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS default_delete<_Tp[]> {
+private:
+  template <class _Up>
+  struct _EnableIfConvertible
+      : enable_if<is_convertible<_Up(*)[], _Tp(*)[]>::value> {};
+
+public:
+#ifndef _LIBCPP_CXX03_LANG
+  _LIBCPP_INLINE_VISIBILITY constexpr default_delete() _NOEXCEPT = default;
+#else
+  _LIBCPP_INLINE_VISIBILITY default_delete() {}
+#endif
+
+  template <class _Up>
+  _LIBCPP_INLINE_VISIBILITY
+  default_delete(const default_delete<_Up[]>&,
+                 typename _EnableIfConvertible<_Up>::type* = 0) _NOEXCEPT {}
+
+  template <class _Up>
+  _LIBCPP_INLINE_VISIBILITY
+  typename _EnableIfConvertible<_Up>::type
+  operator()(_Up* __ptr) const _NOEXCEPT {
+    static_assert(sizeof(_Tp) > 0,
+                  "default_delete can not delete incomplete type");
+    static_assert(!is_void<_Tp>::value,
+                  "default_delete can not delete void type");
+    delete[] __ptr;
+  }
+};
+
+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 _LIBCPP_TEMPLATE_VIS unique_ptr {
+public:
+  typedef _Tp element_type;
+  typedef _Dp deleter_type;
+  typedef _LIBCPP_NODEBUG_TYPE typename __pointer<_Tp, deleter_type>::type pointer;
+
+  static_assert(!is_rvalue_reference<deleter_type>::value,
+                "the specified deleter type cannot be an rvalue reference");
+
+private:
+  __compressed_pair<pointer, deleter_type> __ptr_;
+
+  struct __nat { int __for_bool_; };
+
+  typedef _LIBCPP_NODEBUG_TYPE __unique_ptr_deleter_sfinae<_Dp> _DeleterSFINAE;
+
+  template <bool _Dummy>
+  using _LValRefType _LIBCPP_NODEBUG_TYPE =
+      typename __dependent_type<_DeleterSFINAE, _Dummy>::__lval_ref_type;
+
+  template <bool _Dummy>
+  using _GoodRValRefType _LIBCPP_NODEBUG_TYPE =
+      typename __dependent_type<_DeleterSFINAE, _Dummy>::__good_rval_ref_type;
+
+  template <bool _Dummy>
+  using _BadRValRefType _LIBCPP_NODEBUG_TYPE  =
+      typename __dependent_type<_DeleterSFINAE, _Dummy>::__bad_rval_ref_type;
+
+  template <bool _Dummy, class _Deleter = typename __dependent_type<
+                             __identity<deleter_type>, _Dummy>::type>
+  using _EnableIfDeleterDefaultConstructible _LIBCPP_NODEBUG_TYPE =
+      typename enable_if<is_default_constructible<_Deleter>::value &&
+                         !is_pointer<_Deleter>::value>::type;
+
+  template <class _ArgType>
+  using _EnableIfDeleterConstructible _LIBCPP_NODEBUG_TYPE  =
+      typename enable_if<is_constructible<deleter_type, _ArgType>::value>::type;
+
+  template <class _UPtr, class _Up>
+  using _EnableIfMoveConvertible _LIBCPP_NODEBUG_TYPE  = typename enable_if<
+      is_convertible<typename _UPtr::pointer, pointer>::value &&
+      !is_array<_Up>::value
+  >::type;
+
+  template <class _UDel>
+  using _EnableIfDeleterConvertible _LIBCPP_NODEBUG_TYPE  = typename enable_if<
+      (is_reference<_Dp>::value && is_same<_Dp, _UDel>::value) ||
+      (!is_reference<_Dp>::value && is_convertible<_UDel, _Dp>::value)
+    >::type;
+
+  template <class _UDel>
+  using _EnableIfDeleterAssignable = typename enable_if<
+      is_assignable<_Dp&, _UDel&&>::value
+    >::type;
+
+public:
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterDefaultConstructible<_Dummy> >
+  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_CONSTEXPR unique_ptr() _NOEXCEPT : __ptr_(pointer(), __default_init_tag()) {}
+
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterDefaultConstructible<_Dummy> >
+  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_CONSTEXPR unique_ptr(nullptr_t) _NOEXCEPT : __ptr_(pointer(), __default_init_tag()) {}
+
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterDefaultConstructible<_Dummy> >
+  _LIBCPP_INLINE_VISIBILITY
+  explicit unique_ptr(pointer __p) _NOEXCEPT : __ptr_(__p, __default_init_tag()) {}
+
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterConstructible<_LValRefType<_Dummy> > >
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(pointer __p, _LValRefType<_Dummy> __d) _NOEXCEPT
+      : __ptr_(__p, __d) {}
+
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterConstructible<_GoodRValRefType<_Dummy> > >
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(pointer __p, _GoodRValRefType<_Dummy> __d) _NOEXCEPT
+      : __ptr_(__p, _VSTD::move(__d)) {
+    static_assert(!is_reference<deleter_type>::value,
+                  "rvalue deleter bound to reference");
+  }
+
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterConstructible<_BadRValRefType<_Dummy> > >
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(pointer __p, _BadRValRefType<_Dummy> __d) = delete;
+
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(unique_ptr&& __u) _NOEXCEPT
+      : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {
+  }
+
+  template <class _Up, class _Ep,
+      class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
+      class = _EnableIfDeleterConvertible<_Ep>
+  >
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT
+      : __ptr_(__u.release(), _VSTD::forward<_Ep>(__u.get_deleter())) {}
+
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
+  template <class _Up>
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(auto_ptr<_Up>&& __p,
+             typename enable_if<is_convertible<_Up*, _Tp*>::value &&
+                                    is_same<_Dp, default_delete<_Tp> >::value,
+                                __nat>::type = __nat()) _NOEXCEPT
+      : __ptr_(__p.release(), __default_init_tag()) {}
+#endif
+
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr& operator=(unique_ptr&& __u) _NOEXCEPT {
+    reset(__u.release());
+    __ptr_.second() = _VSTD::forward<deleter_type>(__u.get_deleter());
+    return *this;
+  }
+
+  template <class _Up, class _Ep,
+      class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
+      class = _EnableIfDeleterAssignable<_Ep>
+  >
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr& operator=(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT {
+    reset(__u.release());
+    __ptr_.second() = _VSTD::forward<_Ep>(__u.get_deleter());
+    return *this;
+  }
+
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
+  template <class _Up>
+  _LIBCPP_INLINE_VISIBILITY
+      typename enable_if<is_convertible<_Up*, _Tp*>::value &&
+                             is_same<_Dp, default_delete<_Tp> >::value,
+                         unique_ptr&>::type
+      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_INLINE_VISIBILITY
+  ~unique_ptr() { reset(); }
+
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr& operator=(nullptr_t) _NOEXCEPT {
+    reset();
+    return *this;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  typename add_lvalue_reference<_Tp>::type
+  operator*() const {
+    return *__ptr_.first();
+  }
+  _LIBCPP_INLINE_VISIBILITY
+  pointer operator->() const _NOEXCEPT {
+    return __ptr_.first();
+  }
+  _LIBCPP_INLINE_VISIBILITY
+  pointer get() const _NOEXCEPT {
+    return __ptr_.first();
+  }
+  _LIBCPP_INLINE_VISIBILITY
+  deleter_type& get_deleter() _NOEXCEPT {
+    return __ptr_.second();
+  }
+  _LIBCPP_INLINE_VISIBILITY
+  const deleter_type& get_deleter() const _NOEXCEPT {
+    return __ptr_.second();
+  }
+  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT {
+    return __ptr_.first() != nullptr;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  pointer release() _NOEXCEPT {
+    pointer __t = __ptr_.first();
+    __ptr_.first() = pointer();
+    return __t;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  void reset(pointer __p = pointer()) _NOEXCEPT {
+    pointer __tmp = __ptr_.first();
+    __ptr_.first() = __p;
+    if (__tmp)
+      __ptr_.second()(__tmp);
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  void swap(unique_ptr& __u) _NOEXCEPT {
+    __ptr_.swap(__u.__ptr_);
+  }
+};
+
+
+template <class _Tp, class _Dp>
+class _LIBCPP_UNIQUE_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS unique_ptr<_Tp[], _Dp> {
+public:
+  typedef _Tp element_type;
+  typedef _Dp deleter_type;
+  typedef typename __pointer<_Tp, deleter_type>::type pointer;
+
+private:
+  __compressed_pair<pointer, deleter_type> __ptr_;
+
+  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_TYPE =
+      typename __dependent_type<_DeleterSFINAE, _Dummy>::__lval_ref_type;
+
+  template <bool _Dummy>
+  using _GoodRValRefType _LIBCPP_NODEBUG_TYPE =
+      typename __dependent_type<_DeleterSFINAE, _Dummy>::__good_rval_ref_type;
+
+  template <bool _Dummy>
+  using _BadRValRefType _LIBCPP_NODEBUG_TYPE =
+      typename __dependent_type<_DeleterSFINAE, _Dummy>::__bad_rval_ref_type;
+
+  template <bool _Dummy, class _Deleter = typename __dependent_type<
+                             __identity<deleter_type>, _Dummy>::type>
+  using _EnableIfDeleterDefaultConstructible _LIBCPP_NODEBUG_TYPE  =
+      typename enable_if<is_default_constructible<_Deleter>::value &&
+                         !is_pointer<_Deleter>::value>::type;
+
+  template <class _ArgType>
+  using _EnableIfDeleterConstructible _LIBCPP_NODEBUG_TYPE  =
+      typename enable_if<is_constructible<deleter_type, _ArgType>::value>::type;
+
+  template <class _Pp>
+  using _EnableIfPointerConvertible _LIBCPP_NODEBUG_TYPE  = typename enable_if<
+      _CheckArrayPointerConversion<_Pp>::value
+  >::type;
+
+  template <class _UPtr, class _Up,
+        class _ElemT = typename _UPtr::element_type>
+  using _EnableIfMoveConvertible _LIBCPP_NODEBUG_TYPE  = typename enable_if<
+      is_array<_Up>::value &&
+      is_same<pointer, element_type*>::value &&
+      is_same<typename _UPtr::pointer, _ElemT*>::value &&
+      is_convertible<_ElemT(*)[], element_type(*)[]>::value
+    >::type;
+
+  template <class _UDel>
+  using _EnableIfDeleterConvertible _LIBCPP_NODEBUG_TYPE  = typename enable_if<
+      (is_reference<_Dp>::value && is_same<_Dp, _UDel>::value) ||
+      (!is_reference<_Dp>::value && is_convertible<_UDel, _Dp>::value)
+    >::type;
+
+  template <class _UDel>
+  using _EnableIfDeleterAssignable _LIBCPP_NODEBUG_TYPE  = typename enable_if<
+      is_assignable<_Dp&, _UDel&&>::value
+    >::type;
+
+public:
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterDefaultConstructible<_Dummy> >
+  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_CONSTEXPR unique_ptr() _NOEXCEPT : __ptr_(pointer(), __default_init_tag()) {}
+
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterDefaultConstructible<_Dummy> >
+  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_CONSTEXPR unique_ptr(nullptr_t) _NOEXCEPT : __ptr_(pointer(), __default_init_tag()) {}
+
+  template <class _Pp, bool _Dummy = true,
+            class = _EnableIfDeleterDefaultConstructible<_Dummy>,
+            class = _EnableIfPointerConvertible<_Pp> >
+  _LIBCPP_INLINE_VISIBILITY
+  explicit unique_ptr(_Pp __p) _NOEXCEPT
+      : __ptr_(__p, __default_init_tag()) {}
+
+  template <class _Pp, bool _Dummy = true,
+            class = _EnableIfDeleterConstructible<_LValRefType<_Dummy> >,
+            class = _EnableIfPointerConvertible<_Pp> >
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(_Pp __p, _LValRefType<_Dummy> __d) _NOEXCEPT
+      : __ptr_(__p, __d) {}
+
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterConstructible<_LValRefType<_Dummy> > >
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(nullptr_t, _LValRefType<_Dummy> __d) _NOEXCEPT
+      : __ptr_(nullptr, __d) {}
+
+  template <class _Pp, bool _Dummy = true,
+            class = _EnableIfDeleterConstructible<_GoodRValRefType<_Dummy> >,
+            class = _EnableIfPointerConvertible<_Pp> >
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(_Pp __p, _GoodRValRefType<_Dummy> __d) _NOEXCEPT
+      : __ptr_(__p, _VSTD::move(__d)) {
+    static_assert(!is_reference<deleter_type>::value,
+                  "rvalue deleter bound to reference");
+  }
+
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterConstructible<_GoodRValRefType<_Dummy> > >
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(nullptr_t, _GoodRValRefType<_Dummy> __d) _NOEXCEPT
+      : __ptr_(nullptr, _VSTD::move(__d)) {
+    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_INLINE_VISIBILITY
+  unique_ptr(_Pp __p, _BadRValRefType<_Dummy> __d) = delete;
+
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(unique_ptr&& __u) _NOEXCEPT
+      : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr& operator=(unique_ptr&& __u) _NOEXCEPT {
+    reset(__u.release());
+    __ptr_.second() = _VSTD::forward<deleter_type>(__u.get_deleter());
+    return *this;
+  }
+
+  template <class _Up, class _Ep,
+      class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
+      class = _EnableIfDeleterConvertible<_Ep>
+  >
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT
+      : __ptr_(__u.release(), _VSTD::forward<_Ep>(__u.get_deleter())) {
+  }
+
+  template <class _Up, class _Ep,
+      class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
+      class = _EnableIfDeleterAssignable<_Ep>
+  >
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr&
+  operator=(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT {
+    reset(__u.release());
+    __ptr_.second() = _VSTD::forward<_Ep>(__u.get_deleter());
+    return *this;
+  }
+
+#ifdef _LIBCPP_CXX03_LANG
+  unique_ptr(unique_ptr const&) = delete;
+  unique_ptr& operator=(unique_ptr const&) = delete;
+#endif
+
+public:
+  _LIBCPP_INLINE_VISIBILITY
+  ~unique_ptr() { reset(); }
+
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr& operator=(nullptr_t) _NOEXCEPT {
+    reset();
+    return *this;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  typename add_lvalue_reference<_Tp>::type
+  operator[](size_t __i) const {
+    return __ptr_.first()[__i];
+  }
+  _LIBCPP_INLINE_VISIBILITY
+  pointer get() const _NOEXCEPT {
+    return __ptr_.first();
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  deleter_type& get_deleter() _NOEXCEPT {
+    return __ptr_.second();
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  const deleter_type& get_deleter() const _NOEXCEPT {
+    return __ptr_.second();
+  }
+  _LIBCPP_INLINE_VISIBILITY
+  _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT {
+    return __ptr_.first() != nullptr;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  pointer release() _NOEXCEPT {
+    pointer __t = __ptr_.first();
+    __ptr_.first() = pointer();
+    return __t;
+  }
+
+  template <class _Pp>
+  _LIBCPP_INLINE_VISIBILITY
+  typename enable_if<
+      _CheckArrayPointerConversion<_Pp>::value
+  >::type
+  reset(_Pp __p) _NOEXCEPT {
+    pointer __tmp = __ptr_.first();
+    __ptr_.first() = __p;
+    if (__tmp)
+      __ptr_.second()(__tmp);
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  void reset(nullptr_t = nullptr) _NOEXCEPT {
+    pointer __tmp = __ptr_.first();
+    __ptr_.first() = nullptr;
+    if (__tmp)
+      __ptr_.second()(__tmp);
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  void swap(unique_ptr& __u) _NOEXCEPT {
+    __ptr_.swap(__u.__ptr_);
+  }
+
+};
+
+template <class _Tp, class _Dp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if<
+    __is_swappable<_Dp>::value,
+    void
+>::type
+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_INLINE_VISIBILITY
+bool
+operator==(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return __x.get() == __y.get();}
+
+template <class _T1, class _D1, class _T2, class _D2>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return !(__x == __y);}
+
+template <class _T1, class _D1, class _T2, class _D2>
+inline _LIBCPP_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+bool
+operator>=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return !(__x < __y);}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const unique_ptr<_T1, _D1>& __x, nullptr_t) _NOEXCEPT
+{
+    return !__x;
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(nullptr_t, const unique_ptr<_T1, _D1>& __x) _NOEXCEPT
+{
+    return !__x;
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(const unique_ptr<_T1, _D1>& __x, nullptr_t) _NOEXCEPT
+{
+    return static_cast<bool>(__x);
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(nullptr_t, const unique_ptr<_T1, _D1>& __x) _NOEXCEPT
+{
+    return static_cast<bool>(__x);
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+bool
+operator>(const unique_ptr<_T1, _D1>& __x, nullptr_t)
+{
+    return nullptr < __x;
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>(nullptr_t, const unique_ptr<_T1, _D1>& __x)
+{
+    return __x < nullptr;
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<=(const unique_ptr<_T1, _D1>& __x, nullptr_t)
+{
+    return !(nullptr < __x);
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator<=(nullptr_t, const unique_ptr<_T1, _D1>& __x)
+{
+    return !(__x < nullptr);
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>=(const unique_ptr<_T1, _D1>& __x, nullptr_t)
+{
+    return !(__x < nullptr);
+}
+
+template <class _T1, class _D1>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator>=(nullptr_t, const unique_ptr<_T1, _D1>& __x)
+{
+    return !(nullptr < __x);
+}
+
+#if _LIBCPP_STD_VER > 11
+
+template<class _Tp>
+struct __unique_if
+{
+    typedef unique_ptr<_Tp> __unique_single;
+};
+
+template<class _Tp>
+struct __unique_if<_Tp[]>
+{
+    typedef unique_ptr<_Tp[]> __unique_array_unknown_bound;
+};
+
+template<class _Tp, size_t _Np>
+struct __unique_if<_Tp[_Np]>
+{
+    typedef void __unique_array_known_bound;
+};
+
+template<class _Tp, class... _Args>
+inline _LIBCPP_INLINE_VISIBILITY
+typename __unique_if<_Tp>::__unique_single
+make_unique(_Args&&... __args)
+{
+    return unique_ptr<_Tp>(new _Tp(_VSTD::forward<_Args>(__args)...));
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY
+typename __unique_if<_Tp>::__unique_array_unknown_bound
+make_unique(size_t __n)
+{
+    typedef typename remove_extent<_Tp>::type _Up;
+    return unique_ptr<_Tp>(new _Up[__n]());
+}
+
+template<class _Tp, class... _Args>
+    typename __unique_if<_Tp>::__unique_array_known_bound
+    make_unique(_Args&&...) = delete;
+
+#endif  // _LIBCPP_STD_VER > 11
+
+template <class _Tp> struct _LIBCPP_TEMPLATE_VIS hash;
+
+template <class _Tp, class _Dp>
+#ifdef _LIBCPP_CXX03_LANG
+struct _LIBCPP_TEMPLATE_VIS hash<unique_ptr<_Tp, _Dp> >
+#else
+struct _LIBCPP_TEMPLATE_VIS hash<__enable_hash_helper<
+    unique_ptr<_Tp, _Dp>, typename unique_ptr<_Tp, _Dp>::pointer> >
+#endif
+{
+    typedef unique_ptr<_Tp, _Dp> argument_type;
+    typedef size_t               result_type;
+    _LIBCPP_INLINE_VISIBILITY
+    result_type operator()(const argument_type& __ptr) const
+    {
+        typedef typename argument_type::pointer pointer;
+        return hash<pointer>()(__ptr.get());
+    }
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif  // _LIBCPP___MEMORY_UNIQUE_PTR_H

libcxx/include/memory

 
 void* align(size_t alignment, size_t size, void*& ptr, size_t& space);
 
 }  // std
 
 */
 
 #include <__config>
-#include <__availability>
 #include <type_traits>
 #include <typeinfo>
 #include <compare>
 #include <cstddef>
 #include <cstdint>
 #include <new>
 #include <utility>
 #include <iterator>
 #include <__functional_base>
 #include <iosfwd>
 #include <tuple>
 #include <stdexcept>
 #include <cstring>
 #include <__memory/allocator.h>
 #include <__memory/allocator_traits.h>
 #include <__memory/auto_ptr.h>
 #include <__memory/base.h>
+#include <__memory/compressed_pair.h>
+#include <__memory/gc.h>
 #include <__memory/pointer_traits.h>
+#include <__memory/raw_storage_iterator.h>
+#include <__memory/shared_ptr.h>
 #include <__memory/temporary_buffer.h>
+#include <__memory/uninitialized.h>
+#include <__memory/unique_ptr.h>
 #include <__memory/utilities.h>
-#if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
-#  include <atomic>
-#endif
 #include <version>
 
 #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 _ValueType>
-inline _LIBCPP_INLINE_VISIBILITY
-_ValueType __libcpp_relaxed_load(_ValueType const* __value) {
-#if !defined(_LIBCPP_HAS_NO_THREADS) && \
-    defined(__ATOMIC_RELAXED) &&        \
-    (__has_builtin(__atomic_load_n) || defined(_LIBCPP_COMPILER_GCC))
-    return __atomic_load_n(__value, __ATOMIC_RELAXED);
-#else
-    return *__value;
-#endif
-}
-
-template <class _ValueType>
-inline _LIBCPP_INLINE_VISIBILITY
-_ValueType __libcpp_acquire_load(_ValueType const* __value) {
-#if !defined(_LIBCPP_HAS_NO_THREADS) && \
-    defined(__ATOMIC_ACQUIRE) &&        \
-    (__has_builtin(__atomic_load_n) || defined(_LIBCPP_COMPILER_GCC))
-    return __atomic_load_n(__value, __ATOMIC_ACQUIRE);
-#else
-    return *__value;
-#endif
-}
-
 template <class _Alloc, class _Ptr>
 _LIBCPP_INLINE_VISIBILITY
 void __construct_forward_with_exception_guarantees(_Alloc& __a, _Ptr __begin1, _Ptr __end1, _Ptr& __begin2) {
     static_assert(__is_cpp17_move_insertable<_Alloc>::value,
         "The specified type does not meet the requirements of Cpp17MoveInsertable");
     typedef allocator_traits<_Alloc> _Traits;
     for (; __begin1 != __end1; ++__begin1, (void)++__begin2) {
         _Traits::construct(__a, _VSTD::__to_address(__begin2),

 _LIBCPP_INLINE_VISIBILITY
 void __construct_backward_with_exception_guarantees(_Alloc&, _Tp* __begin1, _Tp* __end1, _Tp*& __end2) {
     ptrdiff_t _Np = __end1 - __begin1;
     __end2 -= _Np;
     if (_Np > 0)
         _VSTD::memcpy(__end2, __begin1, _Np * sizeof(_Tp));
 }
 
-template <class _OutputIterator, class _Tp>
-class _LIBCPP_TEMPLATE_VIS raw_storage_iterator
-    : public iterator<output_iterator_tag,
-                      _Tp,                                         // purposefully not C++03
-                      ptrdiff_t,                                   // purposefully not C++03
-                      _Tp*,                                        // purposefully not C++03
-                      raw_storage_iterator<_OutputIterator, _Tp>&> // purposefully not C++03
-{
-private:
-    _OutputIterator __x_;
-public:
-    _LIBCPP_INLINE_VISIBILITY explicit raw_storage_iterator(_OutputIterator __x) : __x_(__x) {}
-    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator*() {return *this;}
-    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator=(const _Tp& __element)
-        {::new ((void*)_VSTD::addressof(*__x_)) _Tp(__element); return *this;}
-#if _LIBCPP_STD_VER >= 14
-    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator=(_Tp&& __element)
-        {::new ((void*)_VSTD::addressof(*__x_)) _Tp(_VSTD::move(__element)); return *this;}
-#endif
-    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator++() {++__x_; return *this;}
-    _LIBCPP_INLINE_VISIBILITY raw_storage_iterator  operator++(int)
-        {raw_storage_iterator __t(*this); ++__x_; return __t;}
-#if _LIBCPP_STD_VER >= 14
-    _LIBCPP_INLINE_VISIBILITY _OutputIterator base() const { return __x_; }
-#endif
-};
-
-// Tag used to default initialize one or both of the pair's elements.
-struct __default_init_tag {};
-struct __value_init_tag {};
-
-template <class _Tp, int _Idx,
-          bool _CanBeEmptyBase =
-              is_empty<_Tp>::value && !__libcpp_is_final<_Tp>::value>
-struct __compressed_pair_elem {
-  typedef _Tp _ParamT;
-  typedef _Tp& reference;
-  typedef const _Tp& const_reference;
-
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-  __compressed_pair_elem(__default_init_tag) {}
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-  __compressed_pair_elem(__value_init_tag) : __value_() {}
-
-  template <class _Up, class = typename enable_if<
-      !is_same<__compressed_pair_elem, typename decay<_Up>::type>::value
-  >::type>
-  _LIBCPP_INLINE_VISIBILITY
-  _LIBCPP_CONSTEXPR explicit
-  __compressed_pair_elem(_Up&& __u)
-      : __value_(_VSTD::forward<_Up>(__u))
-    {
-    }
-
-
-#ifndef _LIBCPP_CXX03_LANG
-  template <class... _Args, size_t... _Indexes>
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-  __compressed_pair_elem(piecewise_construct_t, tuple<_Args...> __args,
-                         __tuple_indices<_Indexes...>)
-      : __value_(_VSTD::forward<_Args>(_VSTD::get<_Indexes>(__args))...) {}
-#endif
-
-
-  _LIBCPP_INLINE_VISIBILITY reference __get() _NOEXCEPT { return __value_; }
-  _LIBCPP_INLINE_VISIBILITY
-  const_reference __get() const _NOEXCEPT { return __value_; }
-
-private:
-  _Tp __value_;
-};
-
-template <class _Tp, int _Idx>
-struct __compressed_pair_elem<_Tp, _Idx, true> : private _Tp {
-  typedef _Tp _ParamT;
-  typedef _Tp& reference;
-  typedef const _Tp& const_reference;
-  typedef _Tp __value_type;
-
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR __compressed_pair_elem() = default;
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-  __compressed_pair_elem(__default_init_tag) {}
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-  __compressed_pair_elem(__value_init_tag) : __value_type() {}
-
-  template <class _Up, class = typename enable_if<
-        !is_same<__compressed_pair_elem, typename decay<_Up>::type>::value
-  >::type>
-  _LIBCPP_INLINE_VISIBILITY
-  _LIBCPP_CONSTEXPR explicit
-  __compressed_pair_elem(_Up&& __u)
-      : __value_type(_VSTD::forward<_Up>(__u))
-  {}
-
-#ifndef _LIBCPP_CXX03_LANG
-  template <class... _Args, size_t... _Indexes>
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-  __compressed_pair_elem(piecewise_construct_t, tuple<_Args...> __args,
-                         __tuple_indices<_Indexes...>)
-      : __value_type(_VSTD::forward<_Args>(_VSTD::get<_Indexes>(__args))...) {}
-#endif
-
-  _LIBCPP_INLINE_VISIBILITY reference __get() _NOEXCEPT { return *this; }
-  _LIBCPP_INLINE_VISIBILITY
-  const_reference __get() const _NOEXCEPT { return *this; }
-};
-
-template <class _T1, class _T2>
-class __compressed_pair : private __compressed_pair_elem<_T1, 0>,
-                          private __compressed_pair_elem<_T2, 1> {
-public:
-  // NOTE: This static assert should never fire because __compressed_pair
-  // is *almost never* used in a scenario where it's possible for T1 == T2.
-  // (The exception is std::function where it is possible that the function
-  //  object and the allocator have the same type).
-  static_assert((!is_same<_T1, _T2>::value),
-    "__compressed_pair cannot be instantiated when T1 and T2 are the same type; "
-    "The current implementation is NOT ABI-compatible with the previous "
-    "implementation for this configuration");
-
-    typedef _LIBCPP_NODEBUG_TYPE __compressed_pair_elem<_T1, 0> _Base1;
-    typedef _LIBCPP_NODEBUG_TYPE __compressed_pair_elem<_T2, 1> _Base2;
-
-    template <bool _Dummy = true,
-      class = typename enable_if<
-          __dependent_type<is_default_constructible<_T1>, _Dummy>::value &&
-          __dependent_type<is_default_constructible<_T2>, _Dummy>::value
-      >::type
-  >
-  _LIBCPP_INLINE_VISIBILITY
-  _LIBCPP_CONSTEXPR __compressed_pair() : _Base1(__value_init_tag()), _Base2(__value_init_tag()) {}
-
-  template <class _U1, class _U2>
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-  __compressed_pair(_U1&& __t1, _U2&& __t2)
-      : _Base1(_VSTD::forward<_U1>(__t1)), _Base2(_VSTD::forward<_U2>(__t2)) {}
-
-#ifndef _LIBCPP_CXX03_LANG
-  template <class... _Args1, class... _Args2>
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
-  __compressed_pair(piecewise_construct_t __pc, tuple<_Args1...> __first_args,
-                    tuple<_Args2...> __second_args)
-      : _Base1(__pc, _VSTD::move(__first_args),
-               typename __make_tuple_indices<sizeof...(_Args1)>::type()),
-        _Base2(__pc, _VSTD::move(__second_args),
-               typename __make_tuple_indices<sizeof...(_Args2)>::type()) {}
-#endif
-
-  _LIBCPP_INLINE_VISIBILITY
-  typename _Base1::reference first() _NOEXCEPT {
-    return static_cast<_Base1&>(*this).__get();
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  typename _Base1::const_reference first() const _NOEXCEPT {
-    return static_cast<_Base1 const&>(*this).__get();
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  typename _Base2::reference second() _NOEXCEPT {
-    return static_cast<_Base2&>(*this).__get();
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  typename _Base2::const_reference second() const _NOEXCEPT {
-    return static_cast<_Base2 const&>(*this).__get();
-  }
-
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-  static _Base1* __get_first_base(__compressed_pair* __pair) _NOEXCEPT {
-    return static_cast<_Base1*>(__pair);
-  }
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-  static _Base2* __get_second_base(__compressed_pair* __pair) _NOEXCEPT {
-    return static_cast<_Base2*>(__pair);
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  void swap(__compressed_pair& __x)
-    _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
-               __is_nothrow_swappable<_T2>::value)
-  {
-    using _VSTD::swap;
-    swap(first(), __x.first());
-    swap(second(), __x.second());
-  }
-};
-
-template <class _T1, class _T2>
-inline _LIBCPP_INLINE_VISIBILITY
-void swap(__compressed_pair<_T1, _T2>& __x, __compressed_pair<_T1, _T2>& __y)
-    _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
-               __is_nothrow_swappable<_T2>::value) {
-  __x.swap(__y);
-}
-
-// default_delete
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS default_delete {
-    static_assert(!is_function<_Tp>::value,
-                  "default_delete cannot be instantiated for function types");
-#ifndef _LIBCPP_CXX03_LANG
-  _LIBCPP_INLINE_VISIBILITY constexpr default_delete() _NOEXCEPT = default;
-#else
-  _LIBCPP_INLINE_VISIBILITY default_delete() {}
-#endif
-  template <class _Up>
-  _LIBCPP_INLINE_VISIBILITY
-  default_delete(const default_delete<_Up>&,
-                 typename enable_if<is_convertible<_Up*, _Tp*>::value>::type* =
-                     0) _NOEXCEPT {}
-
-  _LIBCPP_INLINE_VISIBILITY void operator()(_Tp* __ptr) const _NOEXCEPT {
-    static_assert(sizeof(_Tp) > 0,
-                  "default_delete can not delete incomplete type");
-    static_assert(!is_void<_Tp>::value,
-                  "default_delete can not delete incomplete type");
-    delete __ptr;
-  }
-};
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS default_delete<_Tp[]> {
-private:
-  template <class _Up>
-  struct _EnableIfConvertible
-      : enable_if<is_convertible<_Up(*)[], _Tp(*)[]>::value> {};
-
-public:
-#ifndef _LIBCPP_CXX03_LANG
-  _LIBCPP_INLINE_VISIBILITY constexpr default_delete() _NOEXCEPT = default;
-#else
-  _LIBCPP_INLINE_VISIBILITY default_delete() {}
-#endif
-
-  template <class _Up>
-  _LIBCPP_INLINE_VISIBILITY
-  default_delete(const default_delete<_Up[]>&,
-                 typename _EnableIfConvertible<_Up>::type* = 0) _NOEXCEPT {}
-
-  template <class _Up>
-  _LIBCPP_INLINE_VISIBILITY
-  typename _EnableIfConvertible<_Up>::type
-  operator()(_Up* __ptr) const _NOEXCEPT {
-    static_assert(sizeof(_Tp) > 0,
-                  "default_delete can not delete incomplete type");
-    static_assert(!is_void<_Tp>::value,
-                  "default_delete can not delete void type");
-    delete[] __ptr;
-  }
-};
-
-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 _LIBCPP_TEMPLATE_VIS unique_ptr {
-public:
-  typedef _Tp element_type;
-  typedef _Dp deleter_type;
-  typedef _LIBCPP_NODEBUG_TYPE typename __pointer<_Tp, deleter_type>::type pointer;
-
-  static_assert(!is_rvalue_reference<deleter_type>::value,
-                "the specified deleter type cannot be an rvalue reference");
-
-private:
-  __compressed_pair<pointer, deleter_type> __ptr_;
-
-  struct __nat { int __for_bool_; };
-
-  typedef _LIBCPP_NODEBUG_TYPE __unique_ptr_deleter_sfinae<_Dp> _DeleterSFINAE;
-
-  template <bool _Dummy>
-  using _LValRefType _LIBCPP_NODEBUG_TYPE =
-      typename __dependent_type<_DeleterSFINAE, _Dummy>::__lval_ref_type;
-
-  template <bool _Dummy>
-  using _GoodRValRefType _LIBCPP_NODEBUG_TYPE =
-      typename __dependent_type<_DeleterSFINAE, _Dummy>::__good_rval_ref_type;
-
-  template <bool _Dummy>
-  using _BadRValRefType _LIBCPP_NODEBUG_TYPE  =
-      typename __dependent_type<_DeleterSFINAE, _Dummy>::__bad_rval_ref_type;
-
-  template <bool _Dummy, class _Deleter = typename __dependent_type<
-                             __identity<deleter_type>, _Dummy>::type>
-  using _EnableIfDeleterDefaultConstructible _LIBCPP_NODEBUG_TYPE =
-      typename enable_if<is_default_constructible<_Deleter>::value &&
-                         !is_pointer<_Deleter>::value>::type;
-
-  template <class _ArgType>
-  using _EnableIfDeleterConstructible _LIBCPP_NODEBUG_TYPE  =
-      typename enable_if<is_constructible<deleter_type, _ArgType>::value>::type;
-
-  template <class _UPtr, class _Up>
-  using _EnableIfMoveConvertible _LIBCPP_NODEBUG_TYPE  = typename enable_if<
-      is_convertible<typename _UPtr::pointer, pointer>::value &&
-      !is_array<_Up>::value
-  >::type;
-
-  template <class _UDel>
-  using _EnableIfDeleterConvertible _LIBCPP_NODEBUG_TYPE  = typename enable_if<
-      (is_reference<_Dp>::value && is_same<_Dp, _UDel>::value) ||
-      (!is_reference<_Dp>::value && is_convertible<_UDel, _Dp>::value)
-    >::type;
-
-  template <class _UDel>
-  using _EnableIfDeleterAssignable = typename enable_if<
-      is_assignable<_Dp&, _UDel&&>::value
-    >::type;
-
-public:
-  template <bool _Dummy = true,
-            class = _EnableIfDeleterDefaultConstructible<_Dummy> >
-  _LIBCPP_INLINE_VISIBILITY
-  _LIBCPP_CONSTEXPR unique_ptr() _NOEXCEPT : __ptr_(pointer(), __default_init_tag()) {}
-
-  template <bool _Dummy = true,
-            class = _EnableIfDeleterDefaultConstructible<_Dummy> >
-  _LIBCPP_INLINE_VISIBILITY
-  _LIBCPP_CONSTEXPR unique_ptr(nullptr_t) _NOEXCEPT : __ptr_(pointer(), __default_init_tag()) {}
-
-  template <bool _Dummy = true,
-            class = _EnableIfDeleterDefaultConstructible<_Dummy> >
-  _LIBCPP_INLINE_VISIBILITY
-  explicit unique_ptr(pointer __p) _NOEXCEPT : __ptr_(__p, __default_init_tag()) {}
-
-  template <bool _Dummy = true,
-            class = _EnableIfDeleterConstructible<_LValRefType<_Dummy> > >
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr(pointer __p, _LValRefType<_Dummy> __d) _NOEXCEPT
-      : __ptr_(__p, __d) {}
-
-  template <bool _Dummy = true,
-            class = _EnableIfDeleterConstructible<_GoodRValRefType<_Dummy> > >
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr(pointer __p, _GoodRValRefType<_Dummy> __d) _NOEXCEPT
-      : __ptr_(__p, _VSTD::move(__d)) {
-    static_assert(!is_reference<deleter_type>::value,
-                  "rvalue deleter bound to reference");
-  }
-
-  template <bool _Dummy = true,
-            class = _EnableIfDeleterConstructible<_BadRValRefType<_Dummy> > >
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr(pointer __p, _BadRValRefType<_Dummy> __d) = delete;
-
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr(unique_ptr&& __u) _NOEXCEPT
-      : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {
-  }
-
-  template <class _Up, class _Ep,
-      class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
-      class = _EnableIfDeleterConvertible<_Ep>
-  >
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT
-      : __ptr_(__u.release(), _VSTD::forward<_Ep>(__u.get_deleter())) {}
-
-#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
-  template <class _Up>
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr(auto_ptr<_Up>&& __p,
-             typename enable_if<is_convertible<_Up*, _Tp*>::value &&
-                                    is_same<_Dp, default_delete<_Tp> >::value,
-                                __nat>::type = __nat()) _NOEXCEPT
-      : __ptr_(__p.release(), __default_init_tag()) {}
-#endif
-
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr& operator=(unique_ptr&& __u) _NOEXCEPT {
-    reset(__u.release());
-    __ptr_.second() = _VSTD::forward<deleter_type>(__u.get_deleter());
-    return *this;
-  }
-
-  template <class _Up, class _Ep,
-      class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
-      class = _EnableIfDeleterAssignable<_Ep>
-  >
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr& operator=(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT {
-    reset(__u.release());
-    __ptr_.second() = _VSTD::forward<_Ep>(__u.get_deleter());
-    return *this;
-  }
-
-#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
-  template <class _Up>
-  _LIBCPP_INLINE_VISIBILITY
-      typename enable_if<is_convertible<_Up*, _Tp*>::value &&
-                             is_same<_Dp, default_delete<_Tp> >::value,
-                         unique_ptr&>::type
-      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_INLINE_VISIBILITY
-  ~unique_ptr() { reset(); }
-
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr& operator=(nullptr_t) _NOEXCEPT {
-    reset();
-    return *this;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  typename add_lvalue_reference<_Tp>::type
-  operator*() const {
-    return *__ptr_.first();
-  }
-  _LIBCPP_INLINE_VISIBILITY
-  pointer operator->() const _NOEXCEPT {
-    return __ptr_.first();
-  }
-  _LIBCPP_INLINE_VISIBILITY
-  pointer get() const _NOEXCEPT {
-    return __ptr_.first();
-  }
-  _LIBCPP_INLINE_VISIBILITY
-  deleter_type& get_deleter() _NOEXCEPT {
-    return __ptr_.second();
-  }
-  _LIBCPP_INLINE_VISIBILITY
-  const deleter_type& get_deleter() const _NOEXCEPT {
-    return __ptr_.second();
-  }
-  _LIBCPP_INLINE_VISIBILITY
-  _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT {
-    return __ptr_.first() != nullptr;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  pointer release() _NOEXCEPT {
-    pointer __t = __ptr_.first();
-    __ptr_.first() = pointer();
-    return __t;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  void reset(pointer __p = pointer()) _NOEXCEPT {
-    pointer __tmp = __ptr_.first();
-    __ptr_.first() = __p;
-    if (__tmp)
-      __ptr_.second()(__tmp);
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  void swap(unique_ptr& __u) _NOEXCEPT {
-    __ptr_.swap(__u.__ptr_);
-  }
-};
-
-
-template <class _Tp, class _Dp>
-class _LIBCPP_UNIQUE_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS unique_ptr<_Tp[], _Dp> {
-public:
-  typedef _Tp element_type;
-  typedef _Dp deleter_type;
-  typedef typename __pointer<_Tp, deleter_type>::type pointer;
-
-private:
-  __compressed_pair<pointer, deleter_type> __ptr_;
-
-  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_TYPE =
-      typename __dependent_type<_DeleterSFINAE, _Dummy>::__lval_ref_type;
-
-  template <bool _Dummy>
-  using _GoodRValRefType _LIBCPP_NODEBUG_TYPE =
-      typename __dependent_type<_DeleterSFINAE, _Dummy>::__good_rval_ref_type;
-
-  template <bool _Dummy>
-  using _BadRValRefType _LIBCPP_NODEBUG_TYPE =
-      typename __dependent_type<_DeleterSFINAE, _Dummy>::__bad_rval_ref_type;
-
-  template <bool _Dummy, class _Deleter = typename __dependent_type<
-                             __identity<deleter_type>, _Dummy>::type>
-  using _EnableIfDeleterDefaultConstructible _LIBCPP_NODEBUG_TYPE  =
-      typename enable_if<is_default_constructible<_Deleter>::value &&
-                         !is_pointer<_Deleter>::value>::type;
-
-  template <class _ArgType>
-  using _EnableIfDeleterConstructible _LIBCPP_NODEBUG_TYPE  =
-      typename enable_if<is_constructible<deleter_type, _ArgType>::value>::type;
-
-  template <class _Pp>
-  using _EnableIfPointerConvertible _LIBCPP_NODEBUG_TYPE  = typename enable_if<
-      _CheckArrayPointerConversion<_Pp>::value
-  >::type;
-
-  template <class _UPtr, class _Up,
-        class _ElemT = typename _UPtr::element_type>
-  using _EnableIfMoveConvertible _LIBCPP_NODEBUG_TYPE  = typename enable_if<
-      is_array<_Up>::value &&
-      is_same<pointer, element_type*>::value &&
-      is_same<typename _UPtr::pointer, _ElemT*>::value &&
-      is_convertible<_ElemT(*)[], element_type(*)[]>::value
-    >::type;
-
-  template <class _UDel>
-  using _EnableIfDeleterConvertible _LIBCPP_NODEBUG_TYPE  = typename enable_if<
-      (is_reference<_Dp>::value && is_same<_Dp, _UDel>::value) ||
-      (!is_reference<_Dp>::value && is_convertible<_UDel, _Dp>::value)
-    >::type;
-
-  template <class _UDel>
-  using _EnableIfDeleterAssignable _LIBCPP_NODEBUG_TYPE  = typename enable_if<
-      is_assignable<_Dp&, _UDel&&>::value
-    >::type;
-
-public:
-  template <bool _Dummy = true,
-            class = _EnableIfDeleterDefaultConstructible<_Dummy> >
-  _LIBCPP_INLINE_VISIBILITY
-  _LIBCPP_CONSTEXPR unique_ptr() _NOEXCEPT : __ptr_(pointer(), __default_init_tag()) {}
-
-  template <bool _Dummy = true,
-            class = _EnableIfDeleterDefaultConstructible<_Dummy> >
-  _LIBCPP_INLINE_VISIBILITY
-  _LIBCPP_CONSTEXPR unique_ptr(nullptr_t) _NOEXCEPT : __ptr_(pointer(), __default_init_tag()) {}
-
-  template <class _Pp, bool _Dummy = true,
-            class = _EnableIfDeleterDefaultConstructible<_Dummy>,
-            class = _EnableIfPointerConvertible<_Pp> >
-  _LIBCPP_INLINE_VISIBILITY
-  explicit unique_ptr(_Pp __p) _NOEXCEPT
-      : __ptr_(__p, __default_init_tag()) {}
-
-  template <class _Pp, bool _Dummy = true,
-            class = _EnableIfDeleterConstructible<_LValRefType<_Dummy> >,
-            class = _EnableIfPointerConvertible<_Pp> >
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr(_Pp __p, _LValRefType<_Dummy> __d) _NOEXCEPT
-      : __ptr_(__p, __d) {}
-
-  template <bool _Dummy = true,
-            class = _EnableIfDeleterConstructible<_LValRefType<_Dummy> > >
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr(nullptr_t, _LValRefType<_Dummy> __d) _NOEXCEPT
-      : __ptr_(nullptr, __d) {}
-
-  template <class _Pp, bool _Dummy = true,
-            class = _EnableIfDeleterConstructible<_GoodRValRefType<_Dummy> >,
-            class = _EnableIfPointerConvertible<_Pp> >
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr(_Pp __p, _GoodRValRefType<_Dummy> __d) _NOEXCEPT
-      : __ptr_(__p, _VSTD::move(__d)) {
-    static_assert(!is_reference<deleter_type>::value,
-                  "rvalue deleter bound to reference");
-  }
-
-  template <bool _Dummy = true,
-            class = _EnableIfDeleterConstructible<_GoodRValRefType<_Dummy> > >
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr(nullptr_t, _GoodRValRefType<_Dummy> __d) _NOEXCEPT
-      : __ptr_(nullptr, _VSTD::move(__d)) {
-    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_INLINE_VISIBILITY
-  unique_ptr(_Pp __p, _BadRValRefType<_Dummy> __d) = delete;
-
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr(unique_ptr&& __u) _NOEXCEPT
-      : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr& operator=(unique_ptr&& __u) _NOEXCEPT {
-    reset(__u.release());
-    __ptr_.second() = _VSTD::forward<deleter_type>(__u.get_deleter());
-    return *this;
-  }
-
-  template <class _Up, class _Ep,
-      class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
-      class = _EnableIfDeleterConvertible<_Ep>
-  >
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT
-      : __ptr_(__u.release(), _VSTD::forward<_Ep>(__u.get_deleter())) {
-  }
-
-  template <class _Up, class _Ep,
-      class = _EnableIfMoveConvertible<unique_ptr<_Up, _Ep>, _Up>,
-      class = _EnableIfDeleterAssignable<_Ep>
-  >
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr&
-  operator=(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT {
-    reset(__u.release());
-    __ptr_.second() = _VSTD::forward<_Ep>(__u.get_deleter());
-    return *this;
-  }
-
-#ifdef _LIBCPP_CXX03_LANG
-  unique_ptr(unique_ptr const&) = delete;
-  unique_ptr& operator=(unique_ptr const&) = delete;
-#endif
-
-public:
-  _LIBCPP_INLINE_VISIBILITY
-  ~unique_ptr() { reset(); }
-
-  _LIBCPP_INLINE_VISIBILITY
-  unique_ptr& operator=(nullptr_t) _NOEXCEPT {
-    reset();
-    return *this;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  typename add_lvalue_reference<_Tp>::type
-  operator[](size_t __i) const {
-    return __ptr_.first()[__i];
-  }
-  _LIBCPP_INLINE_VISIBILITY
-  pointer get() const _NOEXCEPT {
-    return __ptr_.first();
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  deleter_type& get_deleter() _NOEXCEPT {
-    return __ptr_.second();
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  const deleter_type& get_deleter() const _NOEXCEPT {
-    return __ptr_.second();
-  }
-  _LIBCPP_INLINE_VISIBILITY
-  _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT {
-    return __ptr_.first() != nullptr;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  pointer release() _NOEXCEPT {
-    pointer __t = __ptr_.first();
-    __ptr_.first() = pointer();
-    return __t;
-  }
-
-  template <class _Pp>
-  _LIBCPP_INLINE_VISIBILITY
-  typename enable_if<
-      _CheckArrayPointerConversion<_Pp>::value
-  >::type
-  reset(_Pp __p) _NOEXCEPT {
-    pointer __tmp = __ptr_.first();
-    __ptr_.first() = __p;
-    if (__tmp)
-      __ptr_.second()(__tmp);
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  void reset(nullptr_t = nullptr) _NOEXCEPT {
-    pointer __tmp = __ptr_.first();
-    __ptr_.first() = nullptr;
-    if (__tmp)
-      __ptr_.second()(__tmp);
-  }
-
-  _LIBCPP_INLINE_VISIBILITY
-  void swap(unique_ptr& __u) _NOEXCEPT {
-    __ptr_.swap(__u.__ptr_);
-  }
-
-};
-
-template <class _Tp, class _Dp>
-inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if<
-    __is_swappable<_Dp>::value,
-    void
->::type
-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_INLINE_VISIBILITY
-bool
-operator==(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return __x.get() == __y.get();}
-
-template <class _T1, class _D1, class _T2, class _D2>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator!=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return !(__x == __y);}
-
-template <class _T1, class _D1, class _T2, class _D2>
-inline _LIBCPP_INLINE_VISIBILITY
-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_INLINE_VISIBILITY
-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_INLINE_VISIBILITY
-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_INLINE_VISIBILITY
-bool
-operator>=(const unique_ptr<_T1, _D1>& __x, const unique_ptr<_T2, _D2>& __y) {return !(__x < __y);}
-
-template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator==(const unique_ptr<_T1, _D1>& __x, nullptr_t) _NOEXCEPT
-{
-    return !__x;
-}
-
-template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator==(nullptr_t, const unique_ptr<_T1, _D1>& __x) _NOEXCEPT
-{
-    return !__x;
-}
-
-template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator!=(const unique_ptr<_T1, _D1>& __x, nullptr_t) _NOEXCEPT
-{
-    return static_cast<bool>(__x);
-}
-
-template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator!=(nullptr_t, const unique_ptr<_T1, _D1>& __x) _NOEXCEPT
-{
-    return static_cast<bool>(__x);
-}
-
-template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
-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_INLINE_VISIBILITY
-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_INLINE_VISIBILITY
-bool
-operator>(const unique_ptr<_T1, _D1>& __x, nullptr_t)
-{
-    return nullptr < __x;
-}
-
-template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator>(nullptr_t, const unique_ptr<_T1, _D1>& __x)
-{
-    return __x < nullptr;
-}
-
-template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator<=(const unique_ptr<_T1, _D1>& __x, nullptr_t)
-{
-    return !(nullptr < __x);
-}
-
-template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator<=(nullptr_t, const unique_ptr<_T1, _D1>& __x)
-{
-    return !(__x < nullptr);
-}
-
-template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator>=(const unique_ptr<_T1, _D1>& __x, nullptr_t)
-{
-    return !(__x < nullptr);
-}
-
-template <class _T1, class _D1>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator>=(nullptr_t, const unique_ptr<_T1, _D1>& __x)
-{
-    return !(nullptr < __x);
-}
-
-#if _LIBCPP_STD_VER > 11
-
-template<class _Tp>
-struct __unique_if
-{
-    typedef unique_ptr<_Tp> __unique_single;
-};
-
-template<class _Tp>
-struct __unique_if<_Tp[]>
-{
-    typedef unique_ptr<_Tp[]> __unique_array_unknown_bound;
-};
-
-template<class _Tp, size_t _Np>
-struct __unique_if<_Tp[_Np]>
-{
-    typedef void __unique_array_known_bound;
-};
-
-template<class _Tp, class... _Args>
-inline _LIBCPP_INLINE_VISIBILITY
-typename __unique_if<_Tp>::__unique_single
-make_unique(_Args&&... __args)
-{
-    return unique_ptr<_Tp>(new _Tp(_VSTD::forward<_Args>(__args)...));
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-typename __unique_if<_Tp>::__unique_array_unknown_bound
-make_unique(size_t __n)
-{
-    typedef typename remove_extent<_Tp>::type _Up;
-    return unique_ptr<_Tp>(new _Up[__n]());
-}
-
-template<class _Tp, class... _Args>
-    typename __unique_if<_Tp>::__unique_array_known_bound
-    make_unique(_Args&&...) = delete;
-
-#endif  // _LIBCPP_STD_VER > 11
-
-template <class _Tp, class _Dp>
-#ifdef _LIBCPP_CXX03_LANG
-struct _LIBCPP_TEMPLATE_VIS hash<unique_ptr<_Tp, _Dp> >
-#else
-struct _LIBCPP_TEMPLATE_VIS hash<__enable_hash_helper<
-    unique_ptr<_Tp, _Dp>, typename unique_ptr<_Tp, _Dp>::pointer> >
-#endif
-{
-    typedef unique_ptr<_Tp, _Dp> argument_type;
-    typedef size_t               result_type;
-    _LIBCPP_INLINE_VISIBILITY
-    result_type operator()(const argument_type& __ptr) const
-    {
-        typedef typename argument_type::pointer pointer;
-        return hash<pointer>()(__ptr.get());
-    }
-};
-
 struct __destruct_n
 {
 private:
     size_t __size_;
 
     template <class _Tp>
     _LIBCPP_INLINE_VISIBILITY void __process(_Tp* __p, false_type) _NOEXCEPT
         {for (size_t __i = 0; __i < __size_; ++__i, ++__p) __p->~_Tp();}
public:
     _LIBCPP_INLINE_VISIBILITY void __set(size_t __s, _Tp*) _NOEXCEPT
         {__set(__s, integral_constant<bool, is_trivially_destructible<_Tp>::value>());}
 
     template <class _Tp>
     _LIBCPP_INLINE_VISIBILITY void operator()(_Tp* __p) _NOEXCEPT
         {__process(__p, integral_constant<bool, is_trivially_destructible<_Tp>::value>());}
 };
 
-template <class _Alloc>
-class __allocator_destructor
-{
-    typedef _LIBCPP_NODEBUG_TYPE allocator_traits<_Alloc> __alloc_traits;
-public:
-    typedef _LIBCPP_NODEBUG_TYPE typename __alloc_traits::pointer pointer;
-    typedef _LIBCPP_NODEBUG_TYPE typename __alloc_traits::size_type size_type;
-private:
-    _Alloc& __alloc_;
-    size_type __s_;
-public:
-    _LIBCPP_INLINE_VISIBILITY __allocator_destructor(_Alloc& __a, size_type __s)
-             _NOEXCEPT
-        : __alloc_(__a), __s_(__s) {}
-    _LIBCPP_INLINE_VISIBILITY
-    void operator()(pointer __p) _NOEXCEPT
-        {__alloc_traits::deallocate(__alloc_, __p, __s_);}
-};
-
-template <class _InputIterator, class _ForwardIterator>
-_ForwardIterator
-uninitialized_copy(_InputIterator __f, _InputIterator __l, _ForwardIterator __r)
-{
-    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    _ForwardIterator __s = __r;
-    try
-    {
-#endif
-        for (; __f != __l; ++__f, (void) ++__r)
-            ::new ((void*)_VSTD::addressof(*__r)) value_type(*__f);
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    }
-    catch (...)
-    {
-        for (; __s != __r; ++__s)
-            __s->~value_type();
-        throw;
-    }
-#endif
-    return __r;
-}
-
-template <class _InputIterator, class _Size, class _ForwardIterator>
-_ForwardIterator
-uninitialized_copy_n(_InputIterator __f, _Size __n, _ForwardIterator __r)
-{
-    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    _ForwardIterator __s = __r;
-    try
-    {
-#endif
-        for (; __n > 0; ++__f, (void) ++__r, (void) --__n)
-            ::new ((void*)_VSTD::addressof(*__r)) value_type(*__f);
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    }
-    catch (...)
-    {
-        for (; __s != __r; ++__s)
-            __s->~value_type();
-        throw;
-    }
-#endif
-    return __r;
-}
-
-template <class _ForwardIterator, class _Tp>
-void
-uninitialized_fill(_ForwardIterator __f, _ForwardIterator __l, const _Tp& __x)
-{
-    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    _ForwardIterator __s = __f;
-    try
-    {
-#endif
-        for (; __f != __l; ++__f)
-            ::new ((void*)_VSTD::addressof(*__f)) value_type(__x);
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    }
-    catch (...)
-    {
-        for (; __s != __f; ++__s)
-            __s->~value_type();
-        throw;
-    }
-#endif
-}
-
-template <class _ForwardIterator, class _Size, class _Tp>
-_ForwardIterator
-uninitialized_fill_n(_ForwardIterator __f, _Size __n, const _Tp& __x)
-{
-    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    _ForwardIterator __s = __f;
-    try
-    {
-#endif
-        for (; __n > 0; ++__f, (void) --__n)
-            ::new ((void*)_VSTD::addressof(*__f)) value_type(__x);
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    }
-    catch (...)
-    {
-        for (; __s != __f; ++__s)
-            __s->~value_type();
-        throw;
-    }
-#endif
-    return __f;
-}
-
-#if _LIBCPP_STD_VER > 14
-
-template <class _ForwardIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void destroy(_ForwardIterator __first, _ForwardIterator __last) {
-    for (; __first != __last; ++__first)
-        _VSTD::destroy_at(_VSTD::addressof(*__first));
-}
-
-template <class _ForwardIterator, class _Size>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-_ForwardIterator destroy_n(_ForwardIterator __first, _Size __n) {
-    for (; __n > 0; (void)++__first, --__n)
-        _VSTD::destroy_at(_VSTD::addressof(*__first));
-    return __first;
-}
-
-template <class _ForwardIterator>
-inline _LIBCPP_INLINE_VISIBILITY
-void uninitialized_default_construct(_ForwardIterator __first, _ForwardIterator __last) {
-    using _Vt = typename iterator_traits<_ForwardIterator>::value_type;
-    auto __idx = __first;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try {
-#endif
-    for (; __idx != __last; ++__idx)
-        ::new ((void*)_VSTD::addressof(*__idx)) _Vt;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    } catch (...) {
-        _VSTD::destroy(__first, __idx);
-        throw;
-    }
-#endif
-}
-
-template <class _ForwardIterator, class _Size>
-inline _LIBCPP_INLINE_VISIBILITY
-_ForwardIterator uninitialized_default_construct_n(_ForwardIterator __first, _Size __n) {
-    using _Vt = typename iterator_traits<_ForwardIterator>::value_type;
-    auto __idx = __first;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try {
-#endif
-    for (; __n > 0; (void)++__idx, --__n)
-        ::new ((void*)_VSTD::addressof(*__idx)) _Vt;
-    return __idx;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    } catch (...) {
-        _VSTD::destroy(__first, __idx);
-        throw;
-    }
-#endif
-}
-
-
-template <class _ForwardIterator>
-inline _LIBCPP_INLINE_VISIBILITY
-void uninitialized_value_construct(_ForwardIterator __first, _ForwardIterator __last) {
-    using _Vt = typename iterator_traits<_ForwardIterator>::value_type;
-    auto __idx = __first;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try {
-#endif
-    for (; __idx != __last; ++__idx)
-        ::new ((void*)_VSTD::addressof(*__idx)) _Vt();
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    } catch (...) {
-        _VSTD::destroy(__first, __idx);
-        throw;
-    }
-#endif
-}
-
-template <class _ForwardIterator, class _Size>
-inline _LIBCPP_INLINE_VISIBILITY
-_ForwardIterator uninitialized_value_construct_n(_ForwardIterator __first, _Size __n) {
-    using _Vt = typename iterator_traits<_ForwardIterator>::value_type;
-    auto __idx = __first;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try {
-#endif
-    for (; __n > 0; (void)++__idx, --__n)
-        ::new ((void*)_VSTD::addressof(*__idx)) _Vt();
-    return __idx;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    } catch (...) {
-        _VSTD::destroy(__first, __idx);
-        throw;
-    }
-#endif
-}
-
-
-template <class _InputIt, class _ForwardIt>
-inline _LIBCPP_INLINE_VISIBILITY
-_ForwardIt uninitialized_move(_InputIt __first, _InputIt __last, _ForwardIt __first_res) {
-    using _Vt = typename iterator_traits<_ForwardIt>::value_type;
-    auto __idx = __first_res;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try {
-#endif
-    for (; __first != __last; (void)++__idx, ++__first)
-        ::new ((void*)_VSTD::addressof(*__idx)) _Vt(_VSTD::move(*__first));
-    return __idx;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    } catch (...) {
-        _VSTD::destroy(__first_res, __idx);
-        throw;
-    }
-#endif
-}
-
-template <class _InputIt, class _Size, class _ForwardIt>
-inline _LIBCPP_INLINE_VISIBILITY
-pair<_InputIt, _ForwardIt>
-uninitialized_move_n(_InputIt __first, _Size __n, _ForwardIt __first_res) {
-    using _Vt = typename iterator_traits<_ForwardIt>::value_type;
-    auto __idx = __first_res;
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try {
-#endif
-    for (; __n > 0; ++__idx, (void)++__first, --__n)
-        ::new ((void*)_VSTD::addressof(*__idx)) _Vt(_VSTD::move(*__first));
-    return {__first, __idx};
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    } catch (...) {
-        _VSTD::destroy(__first_res, __idx);
-        throw;
-    }
-#endif
-}
-
-
-#endif // _LIBCPP_STD_VER > 14
-
-// NOTE: Relaxed and acq/rel atomics (for increment and decrement respectively)
-// should be sufficient for thread safety.
-// See https://llvm.org/PR22803
-#if defined(__clang__) && __has_builtin(__atomic_add_fetch)          \
-                       && defined(__ATOMIC_RELAXED)                  \
-                       && defined(__ATOMIC_ACQ_REL)
-#   define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT
-#elif defined(_LIBCPP_COMPILER_GCC)
-#   define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT
-#endif
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _Tp
-__libcpp_atomic_refcount_increment(_Tp& __t) _NOEXCEPT
-{
-#if defined(_LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT) && !defined(_LIBCPP_HAS_NO_THREADS)
-    return __atomic_add_fetch(&__t, 1, __ATOMIC_RELAXED);
-#else
-    return __t += 1;
-#endif
-}
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY _Tp
-__libcpp_atomic_refcount_decrement(_Tp& __t) _NOEXCEPT
-{
-#if defined(_LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT) && !defined(_LIBCPP_HAS_NO_THREADS)
-    return __atomic_add_fetch(&__t, -1, __ATOMIC_ACQ_REL);
-#else
-    return __t -= 1;
-#endif
-}
-
-class _LIBCPP_EXCEPTION_ABI bad_weak_ptr
-    : public std::exception
-{
-public:
-    bad_weak_ptr() _NOEXCEPT = default;
-    bad_weak_ptr(const bad_weak_ptr&) _NOEXCEPT = default;
-    virtual ~bad_weak_ptr() _NOEXCEPT;
-    virtual const char* what() const  _NOEXCEPT;
-};
-
-_LIBCPP_NORETURN inline _LIBCPP_INLINE_VISIBILITY
-void __throw_bad_weak_ptr()
-{
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    throw bad_weak_ptr();
-#else
-    _VSTD::abort();
-#endif
-}
-
-template<class _Tp> class _LIBCPP_TEMPLATE_VIS weak_ptr;
-
-class _LIBCPP_TYPE_VIS __shared_count
-{
-    __shared_count(const __shared_count&);
-    __shared_count& operator=(const __shared_count&);
-
-protected:
-    long __shared_owners_;
-    virtual ~__shared_count();
-private:
-    virtual void __on_zero_shared() _NOEXCEPT = 0;
-
-public:
-    _LIBCPP_INLINE_VISIBILITY
-    explicit __shared_count(long __refs = 0) _NOEXCEPT
-        : __shared_owners_(__refs) {}
-
-#if defined(_LIBCPP_BUILDING_LIBRARY) && \
-    defined(_LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS)
-    void __add_shared() _NOEXCEPT;
-    bool __release_shared() _NOEXCEPT;
-#else
-    _LIBCPP_INLINE_VISIBILITY
-    void __add_shared() _NOEXCEPT {
-      __libcpp_atomic_refcount_increment(__shared_owners_);
-    }
-    _LIBCPP_INLINE_VISIBILITY
-    bool __release_shared() _NOEXCEPT {
-      if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1) {
-        __on_zero_shared();
-        return true;
-      }
-      return false;
-    }
-#endif
-    _LIBCPP_INLINE_VISIBILITY
-    long use_count() const _NOEXCEPT {
-        return __libcpp_relaxed_load(&__shared_owners_) + 1;
-    }
-};
-
-class _LIBCPP_TYPE_VIS __shared_weak_count
-    : private __shared_count
-{
-    long __shared_weak_owners_;
-
-public:
-    _LIBCPP_INLINE_VISIBILITY
-    explicit __shared_weak_count(long __refs = 0) _NOEXCEPT
-        : __shared_count(__refs),
-          __shared_weak_owners_(__refs) {}
-protected:
-    virtual ~__shared_weak_count();
-
-public:
-#if defined(_LIBCPP_BUILDING_LIBRARY) && \
-    defined(_LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS)
-    void __add_shared() _NOEXCEPT;
-    void __add_weak() _NOEXCEPT;
-    void __release_shared() _NOEXCEPT;
-#else
-    _LIBCPP_INLINE_VISIBILITY
-    void __add_shared() _NOEXCEPT {
-      __shared_count::__add_shared();
-    }
-    _LIBCPP_INLINE_VISIBILITY
-    void __add_weak() _NOEXCEPT {
-      __libcpp_atomic_refcount_increment(__shared_weak_owners_);
-    }
-    _LIBCPP_INLINE_VISIBILITY
-    void __release_shared() _NOEXCEPT {
-      if (__shared_count::__release_shared())
-        __release_weak();
-    }
-#endif
-    void __release_weak() _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    long use_count() const _NOEXCEPT {return __shared_count::use_count();}
-    __shared_weak_count* lock() _NOEXCEPT;
-
-    virtual const void* __get_deleter(const type_info&) const _NOEXCEPT;
-private:
-    virtual void __on_zero_shared_weak() _NOEXCEPT = 0;
-};
-
-template <class _Tp, class _Dp, class _Alloc>
-class __shared_ptr_pointer
-    : public __shared_weak_count
-{
-    __compressed_pair<__compressed_pair<_Tp, _Dp>, _Alloc> __data_;
-public:
-    _LIBCPP_INLINE_VISIBILITY
-    __shared_ptr_pointer(_Tp __p, _Dp __d, _Alloc __a)
-        :  __data_(__compressed_pair<_Tp, _Dp>(__p, _VSTD::move(__d)), _VSTD::move(__a)) {}
-
-#ifndef _LIBCPP_NO_RTTI
-    virtual const void* __get_deleter(const type_info&) const _NOEXCEPT;
-#endif
-
-private:
-    virtual void __on_zero_shared() _NOEXCEPT;
-    virtual void __on_zero_shared_weak() _NOEXCEPT;
-};
-
-#ifndef _LIBCPP_NO_RTTI
-
-template <class _Tp, class _Dp, class _Alloc>
-const void*
-__shared_ptr_pointer<_Tp, _Dp, _Alloc>::__get_deleter(const type_info& __t) const _NOEXCEPT
-{
-    return __t == typeid(_Dp) ? _VSTD::addressof(__data_.first().second()) : nullptr;
-}
-
-#endif  // _LIBCPP_NO_RTTI
-
-template <class _Tp, class _Dp, class _Alloc>
-void
-__shared_ptr_pointer<_Tp, _Dp, _Alloc>::__on_zero_shared() _NOEXCEPT
-{
-    __data_.first().second()(__data_.first().first());
-    __data_.first().second().~_Dp();
-}
-
-template <class _Tp, class _Dp, class _Alloc>
-void
-__shared_ptr_pointer<_Tp, _Dp, _Alloc>::__on_zero_shared_weak() _NOEXCEPT
-{
-    typedef typename __allocator_traits_rebind<_Alloc, __shared_ptr_pointer>::type _Al;
-    typedef allocator_traits<_Al> _ATraits;
-    typedef pointer_traits<typename _ATraits::pointer> _PTraits;
-
-    _Al __a(__data_.second());
-    __data_.second().~_Alloc();
-    __a.deallocate(_PTraits::pointer_to(*this), 1);
-}
-
-template <class _Tp, class _Alloc>
-struct __shared_ptr_emplace
-    : __shared_weak_count
-{
-    template<class ..._Args>
-    _LIBCPP_HIDE_FROM_ABI
-    explicit __shared_ptr_emplace(_Alloc __a, _Args&& ...__args)
-        : __storage_(_VSTD::move(__a))
-    {
-#if _LIBCPP_STD_VER > 17
-        using _TpAlloc = typename __allocator_traits_rebind<_Alloc, _Tp>::type;
-        _TpAlloc __tmp(*__get_alloc());
-        allocator_traits<_TpAlloc>::construct(__tmp, __get_elem(), _VSTD::forward<_Args>(__args)...);
-#else
-        ::new ((void*)__get_elem()) _Tp(_VSTD::forward<_Args>(__args)...);
-#endif
-    }
-
-    _LIBCPP_HIDE_FROM_ABI
-    _Alloc* __get_alloc() _NOEXCEPT { return __storage_.__get_alloc(); }
-
-    _LIBCPP_HIDE_FROM_ABI
-    _Tp* __get_elem() _NOEXCEPT { return __storage_.__get_elem(); }
-
-private:
-    virtual void __on_zero_shared() _NOEXCEPT {
-#if _LIBCPP_STD_VER > 17
-        using _TpAlloc = typename __allocator_traits_rebind<_Alloc, _Tp>::type;
-        _TpAlloc __tmp(*__get_alloc());
-        allocator_traits<_TpAlloc>::destroy(__tmp, __get_elem());
-#else
-        __get_elem()->~_Tp();
-#endif
-    }
-
-    virtual void __on_zero_shared_weak() _NOEXCEPT {
-        using _ControlBlockAlloc = typename __allocator_traits_rebind<_Alloc, __shared_ptr_emplace>::type;
-        using _ControlBlockPointer = typename allocator_traits<_ControlBlockAlloc>::pointer;
-        _ControlBlockAlloc __tmp(*__get_alloc());
-        __storage_.~_Storage();
-        allocator_traits<_ControlBlockAlloc>::deallocate(__tmp,
-            pointer_traits<_ControlBlockPointer>::pointer_to(*this), 1);
-    }
-
-    // This class implements the control block for non-array shared pointers created
-    // through `std::allocate_shared` and `std::make_shared`.
-    //
-    // In previous versions of the library, we used a compressed pair to store
-    // both the _Alloc and the _Tp. This implies using EBO, which is incompatible
-    // with Allocator construction for _Tp. To allow implementing P0674 in C++20,
-    // we now use a properly aligned char buffer while making sure that we maintain
-    // the same layout that we had when we used a compressed pair.
-    using _CompressedPair = __compressed_pair<_Alloc, _Tp>;
-    struct _ALIGNAS_TYPE(_CompressedPair) _Storage {
-        char __blob_[sizeof(_CompressedPair)];
-
-        _LIBCPP_HIDE_FROM_ABI explicit _Storage(_Alloc&& __a) {
-            ::new ((void*)__get_alloc()) _Alloc(_VSTD::move(__a));
-        }
-        _LIBCPP_HIDE_FROM_ABI ~_Storage() {
-            __get_alloc()->~_Alloc();
-        }
-        _Alloc* __get_alloc() _NOEXCEPT {
-            _CompressedPair *__as_pair = reinterpret_cast<_CompressedPair*>(__blob_);
-            typename _CompressedPair::_Base1* __first = _CompressedPair::__get_first_base(__as_pair);
-            _Alloc *__alloc = reinterpret_cast<_Alloc*>(__first);
-            return __alloc;
-        }
-        _LIBCPP_NO_CFI _Tp* __get_elem() _NOEXCEPT {
-            _CompressedPair *__as_pair = reinterpret_cast<_CompressedPair*>(__blob_);
-            typename _CompressedPair::_Base2* __second = _CompressedPair::__get_second_base(__as_pair);
-            _Tp *__elem = reinterpret_cast<_Tp*>(__second);
-            return __elem;
-        }
-    };
-
-    static_assert(_LIBCPP_ALIGNOF(_Storage) == _LIBCPP_ALIGNOF(_CompressedPair), "");
-    static_assert(sizeof(_Storage) == sizeof(_CompressedPair), "");
-    _Storage __storage_;
-};
-
-struct __shared_ptr_dummy_rebind_allocator_type;
-template <>
-class _LIBCPP_TEMPLATE_VIS allocator<__shared_ptr_dummy_rebind_allocator_type>
-{
-public:
-    template <class _Other>
-    struct rebind
-    {
-        typedef allocator<_Other> other;
-    };
-};
-
-template<class _Tp> class _LIBCPP_TEMPLATE_VIS enable_shared_from_this;
-
-template<class _Tp, class _Up>
-struct __compatible_with
-#if _LIBCPP_STD_VER > 14
-    : is_convertible<remove_extent_t<_Tp>*, remove_extent_t<_Up>*> {};
-#else
-    : is_convertible<_Tp*, _Up*> {};
-#endif // _LIBCPP_STD_VER > 14
-
-template <class _Dp, class _Pt,
-    class = decltype(_VSTD::declval<_Dp>()(_VSTD::declval<_Pt>()))>
-static true_type __well_formed_deleter_test(int);
-
-template <class, class>
-static false_type __well_formed_deleter_test(...);
-
-template <class _Dp, class _Pt>
-struct __well_formed_deleter : decltype(__well_formed_deleter_test<_Dp, _Pt>(0)) {};
-
-template<class _Dp, class _Tp, class _Yp>
-struct __shared_ptr_deleter_ctor_reqs
-{
-    static const bool value = __compatible_with<_Tp, _Yp>::value &&
-                              is_move_constructible<_Dp>::value &&
-                              __well_formed_deleter<_Dp, _Tp*>::value;
-};
-
-#if defined(_LIBCPP_ABI_ENABLE_SHARED_PTR_TRIVIAL_ABI)
-#  define _LIBCPP_SHARED_PTR_TRIVIAL_ABI __attribute__((trivial_abi))
-#else
-#  define _LIBCPP_SHARED_PTR_TRIVIAL_ABI
-#endif
-
-template<class _Tp>
-class _LIBCPP_SHARED_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS shared_ptr
-{
-public:
-#if _LIBCPP_STD_VER > 14
-    typedef weak_ptr<_Tp> weak_type;
-    typedef remove_extent_t<_Tp> element_type;
-#else
-    typedef _Tp element_type;
-#endif
-
-private:
-    element_type*      __ptr_;
-    __shared_weak_count* __cntrl_;
-
-    struct __nat {int __for_bool_;};
-public:
-    _LIBCPP_INLINE_VISIBILITY
-    _LIBCPP_CONSTEXPR shared_ptr() _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    _LIBCPP_CONSTEXPR shared_ptr(nullptr_t) _NOEXCEPT;
-    template<class _Yp>
-        explicit shared_ptr(_Yp* __p,
-                            typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type = __nat());
-    template<class _Yp, class _Dp>
-        shared_ptr(_Yp* __p, _Dp __d,
-                   typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type = __nat());
-    template<class _Yp, class _Dp, class _Alloc>
-        shared_ptr(_Yp* __p, _Dp __d, _Alloc __a,
-                   typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type = __nat());
-    template <class _Dp> shared_ptr(nullptr_t __p, _Dp __d);
-    template <class _Dp, class _Alloc> shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a);
-    template<class _Yp> _LIBCPP_INLINE_VISIBILITY shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    shared_ptr(const shared_ptr& __r) _NOEXCEPT;
-    template<class _Yp>
-        _LIBCPP_INLINE_VISIBILITY
-        shared_ptr(const shared_ptr<_Yp>& __r,
-                   typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type = __nat())
-                       _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    shared_ptr(shared_ptr&& __r) _NOEXCEPT;
-    template<class _Yp> _LIBCPP_INLINE_VISIBILITY  shared_ptr(shared_ptr<_Yp>&& __r,
-                   typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type = __nat())
-                       _NOEXCEPT;
-    template<class _Yp> explicit shared_ptr(const weak_ptr<_Yp>& __r,
-                   typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type= __nat());
-#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
-    template<class _Yp>
-        shared_ptr(auto_ptr<_Yp>&& __r,
-                   typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type = __nat());
-#endif
-    template <class _Yp, class _Dp>
-        shared_ptr(unique_ptr<_Yp, _Dp>&&,
-                   typename enable_if
-                   <
-                       !is_lvalue_reference<_Dp>::value &&
-                       is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
-                       __nat
-                   >::type = __nat());
-    template <class _Yp, class _Dp>
-        shared_ptr(unique_ptr<_Yp, _Dp>&&,
-                   typename enable_if
-                   <
-                       is_lvalue_reference<_Dp>::value &&
-                       is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
-                       __nat
-                   >::type = __nat());
-
-    ~shared_ptr();
-
-    _LIBCPP_INLINE_VISIBILITY
-    shared_ptr& operator=(const shared_ptr& __r) _NOEXCEPT;
-    template<class _Yp>
-        typename enable_if
-        <
-            __compatible_with<_Yp, element_type>::value,
-            shared_ptr&
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    shared_ptr& operator=(shared_ptr&& __r) _NOEXCEPT;
-    template<class _Yp>
-        typename enable_if
-        <
-            __compatible_with<_Yp, element_type>::value,
-            shared_ptr&
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        operator=(shared_ptr<_Yp>&& __r);
-#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
-    template<class _Yp>
-        _LIBCPP_INLINE_VISIBILITY
-        typename enable_if
-        <
-            !is_array<_Yp>::value &&
-            is_convertible<_Yp*, element_type*>::value,
-            shared_ptr
-        >::type&
-        operator=(auto_ptr<_Yp>&& __r);
-#endif
-    template <class _Yp, class _Dp>
-        typename enable_if
-        <
-            is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
-            shared_ptr&
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        operator=(unique_ptr<_Yp, _Dp>&& __r);
-
-    _LIBCPP_INLINE_VISIBILITY
-    void swap(shared_ptr& __r) _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    void reset() _NOEXCEPT;
-    template<class _Yp>
-        typename enable_if
-        <
-            __compatible_with<_Yp, element_type>::value,
-            void
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        reset(_Yp* __p);
-    template<class _Yp, class _Dp>
-        typename enable_if
-        <
-            __compatible_with<_Yp, element_type>::value,
-            void
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        reset(_Yp* __p, _Dp __d);
-    template<class _Yp, class _Dp, class _Alloc>
-        typename enable_if
-        <
-            __compatible_with<_Yp, element_type>::value,
-            void
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        reset(_Yp* __p, _Dp __d, _Alloc __a);
-
-    _LIBCPP_INLINE_VISIBILITY
-    element_type* get() const _NOEXCEPT {return __ptr_;}
-    _LIBCPP_INLINE_VISIBILITY
-    typename add_lvalue_reference<element_type>::type operator*() const _NOEXCEPT
-        {return *__ptr_;}
-    _LIBCPP_INLINE_VISIBILITY
-    element_type* operator->() const _NOEXCEPT
-    {
-        static_assert(!_VSTD::is_array<_Tp>::value,
-                      "std::shared_ptr<T>::operator-> is only valid when T is not an array type.");
-        return __ptr_;
-    }
-    _LIBCPP_INLINE_VISIBILITY
-    long use_count() const _NOEXCEPT {return __cntrl_ ? __cntrl_->use_count() : 0;}
-    _LIBCPP_INLINE_VISIBILITY
-    bool unique() const _NOEXCEPT {return use_count() == 1;}
-    _LIBCPP_INLINE_VISIBILITY
-    _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT {return get() != nullptr;}
-    template <class _Up>
-        _LIBCPP_INLINE_VISIBILITY
-        bool owner_before(shared_ptr<_Up> const& __p) const _NOEXCEPT
-        {return __cntrl_ < __p.__cntrl_;}
-    template <class _Up>
-        _LIBCPP_INLINE_VISIBILITY
-        bool owner_before(weak_ptr<_Up> const& __p) const _NOEXCEPT
-        {return __cntrl_ < __p.__cntrl_;}
-    _LIBCPP_INLINE_VISIBILITY
-    bool
-    __owner_equivalent(const shared_ptr& __p) const
-        {return __cntrl_ == __p.__cntrl_;}
-
-#if _LIBCPP_STD_VER > 14
-    typename add_lvalue_reference<element_type>::type
-    _LIBCPP_INLINE_VISIBILITY
-    operator[](ptrdiff_t __i) const
-    {
-            static_assert(_VSTD::is_array<_Tp>::value,
-                          "std::shared_ptr<T>::operator[] is only valid when T is an array type.");
-            return __ptr_[__i];
-    }
-#endif
-
-#ifndef _LIBCPP_NO_RTTI
-    template <class _Dp>
-        _LIBCPP_INLINE_VISIBILITY
-        _Dp* __get_deleter() const _NOEXCEPT
-            {return static_cast<_Dp*>(__cntrl_
-                    ? const_cast<void *>(__cntrl_->__get_deleter(typeid(_Dp)))
-                      : nullptr);}
-#endif  // _LIBCPP_NO_RTTI
-
-    template<class _Yp, class _CntrlBlk>
-    static shared_ptr<_Tp>
-    __create_with_control_block(_Yp* __p, _CntrlBlk* __cntrl) _NOEXCEPT
-    {
-        shared_ptr<_Tp> __r;
-        __r.__ptr_ = __p;
-        __r.__cntrl_ = __cntrl;
-        __r.__enable_weak_this(__r.__ptr_, __r.__ptr_);
-        return __r;
-    }
-
-private:
-    template <class _Yp, bool = is_function<_Yp>::value>
-        struct __shared_ptr_default_allocator
-        {
-            typedef allocator<_Yp> type;
-        };
-
-    template <class _Yp>
-        struct __shared_ptr_default_allocator<_Yp, true>
-        {
-            typedef allocator<__shared_ptr_dummy_rebind_allocator_type> type;
-        };
-
-    template <class _Yp, class _OrigPtr>
-        _LIBCPP_INLINE_VISIBILITY
-        typename enable_if<is_convertible<_OrigPtr*,
-                                          const enable_shared_from_this<_Yp>*
-        >::value,
-            void>::type
-        __enable_weak_this(const enable_shared_from_this<_Yp>* __e,
-                           _OrigPtr* __ptr) _NOEXCEPT
-        {
-            typedef typename remove_cv<_Yp>::type _RawYp;
-            if (__e && __e->__weak_this_.expired())
-            {
-                __e->__weak_this_ = shared_ptr<_RawYp>(*this,
-                    const_cast<_RawYp*>(static_cast<const _Yp*>(__ptr)));
-            }
-        }
-
-    _LIBCPP_INLINE_VISIBILITY void __enable_weak_this(...) _NOEXCEPT {}
-
-    template <class, class _Yp>
-        struct __shared_ptr_default_delete
-            : default_delete<_Yp> {};
-
-    template <class _Yp, class _Un, size_t _Sz>
-        struct __shared_ptr_default_delete<_Yp[_Sz], _Un>
-            : default_delete<_Yp[]> {};
-
-    template <class _Yp, class _Un>
-        struct __shared_ptr_default_delete<_Yp[], _Un>
-            : default_delete<_Yp[]> {};
-
-    template <class _Up> friend class _LIBCPP_TEMPLATE_VIS shared_ptr;
-    template <class _Up> friend class _LIBCPP_TEMPLATE_VIS weak_ptr;
-};
-
-#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
-template<class _Tp>
-shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>;
-template<class _Tp, class _Dp>
-shared_ptr(unique_ptr<_Tp, _Dp>) -> shared_ptr<_Tp>;
-#endif
-
-template<class _Tp>
-inline
-_LIBCPP_CONSTEXPR
-shared_ptr<_Tp>::shared_ptr() _NOEXCEPT
-    : __ptr_(nullptr),
-      __cntrl_(nullptr)
-{
-}
-
-template<class _Tp>
-inline
-_LIBCPP_CONSTEXPR
-shared_ptr<_Tp>::shared_ptr(nullptr_t) _NOEXCEPT
-    : __ptr_(nullptr),
-      __cntrl_(nullptr)
-{
-}
-
-template<class _Tp>
-template<class _Yp>
-shared_ptr<_Tp>::shared_ptr(_Yp* __p,
-                            typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type)
-    : __ptr_(__p)
-{
-    unique_ptr<_Yp> __hold(__p);
-    typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
-    typedef __shared_ptr_pointer<_Yp*, __shared_ptr_default_delete<_Tp, _Yp>, _AllocT > _CntrlBlk;
-    __cntrl_ = new _CntrlBlk(__p, __shared_ptr_default_delete<_Tp, _Yp>(), _AllocT());
-    __hold.release();
-    __enable_weak_this(__p, __p);
-}
-
-template<class _Tp>
-template<class _Yp, class _Dp>
-shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d,
-                            typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type)
-    : __ptr_(__p)
-{
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try
-    {
-#endif  // _LIBCPP_NO_EXCEPTIONS
-        typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
-        typedef __shared_ptr_pointer<_Yp*, _Dp, _AllocT > _CntrlBlk;
-#ifndef _LIBCPP_CXX03_LANG
-        __cntrl_ = new _CntrlBlk(__p, _VSTD::move(__d), _AllocT());
-#else
-        __cntrl_ = new _CntrlBlk(__p, __d, _AllocT());
-#endif // not _LIBCPP_CXX03_LANG
-        __enable_weak_this(__p, __p);
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    }
-    catch (...)
-    {
-        __d(__p);
-        throw;
-    }
-#endif  // _LIBCPP_NO_EXCEPTIONS
-}
-
-template<class _Tp>
-template<class _Dp>
-shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d)
-    : __ptr_(nullptr)
-{
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try
-    {
-#endif  // _LIBCPP_NO_EXCEPTIONS
-        typedef typename __shared_ptr_default_allocator<_Tp>::type _AllocT;
-        typedef __shared_ptr_pointer<nullptr_t, _Dp, _AllocT > _CntrlBlk;
-#ifndef _LIBCPP_CXX03_LANG
-        __cntrl_ = new _CntrlBlk(__p, _VSTD::move(__d), _AllocT());
-#else
-        __cntrl_ = new _CntrlBlk(__p, __d, _AllocT());
-#endif // not _LIBCPP_CXX03_LANG
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    }
-    catch (...)
-    {
-        __d(__p);
-        throw;
-    }
-#endif  // _LIBCPP_NO_EXCEPTIONS
-}
-
-template<class _Tp>
-template<class _Yp, class _Dp, class _Alloc>
-shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d, _Alloc __a,
-                            typename enable_if<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value, __nat>::type)
-    : __ptr_(__p)
-{
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try
-    {
-#endif  // _LIBCPP_NO_EXCEPTIONS
-        typedef __shared_ptr_pointer<_Yp*, _Dp, _Alloc> _CntrlBlk;
-        typedef typename __allocator_traits_rebind<_Alloc, _CntrlBlk>::type _A2;
-        typedef __allocator_destructor<_A2> _D2;
-        _A2 __a2(__a);
-        unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
-        ::new ((void*)_VSTD::addressof(*__hold2.get()))
-#ifndef _LIBCPP_CXX03_LANG
-            _CntrlBlk(__p, _VSTD::move(__d), __a);
-#else
-            _CntrlBlk(__p, __d, __a);
-#endif // not _LIBCPP_CXX03_LANG
-        __cntrl_ = _VSTD::addressof(*__hold2.release());
-        __enable_weak_this(__p, __p);
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    }
-    catch (...)
-    {
-        __d(__p);
-        throw;
-    }
-#endif  // _LIBCPP_NO_EXCEPTIONS
-}
-
-template<class _Tp>
-template<class _Dp, class _Alloc>
-shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a)
-    : __ptr_(nullptr)
-{
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    try
-    {
-#endif  // _LIBCPP_NO_EXCEPTIONS
-        typedef __shared_ptr_pointer<nullptr_t, _Dp, _Alloc> _CntrlBlk;
-        typedef typename __allocator_traits_rebind<_Alloc, _CntrlBlk>::type _A2;
-        typedef __allocator_destructor<_A2> _D2;
-        _A2 __a2(__a);
-        unique_ptr<_CntrlBlk, _D2> __hold2(__a2.allocate(1), _D2(__a2, 1));
-        ::new ((void*)_VSTD::addressof(*__hold2.get()))
-#ifndef _LIBCPP_CXX03_LANG
-            _CntrlBlk(__p, _VSTD::move(__d), __a);
-#else
-            _CntrlBlk(__p, __d, __a);
-#endif // not _LIBCPP_CXX03_LANG
-        __cntrl_ = _VSTD::addressof(*__hold2.release());
-#ifndef _LIBCPP_NO_EXCEPTIONS
-    }
-    catch (...)
-    {
-        __d(__p);
-        throw;
-    }
-#endif  // _LIBCPP_NO_EXCEPTIONS
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-shared_ptr<_Tp>::shared_ptr(const shared_ptr<_Yp>& __r, element_type *__p) _NOEXCEPT
-    : __ptr_(__p),
-      __cntrl_(__r.__cntrl_)
-{
-    if (__cntrl_)
-        __cntrl_->__add_shared();
-}
-
-template<class _Tp>
-inline
-shared_ptr<_Tp>::shared_ptr(const shared_ptr& __r) _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    if (__cntrl_)
-        __cntrl_->__add_shared();
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-shared_ptr<_Tp>::shared_ptr(const shared_ptr<_Yp>& __r,
-                            typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type)
-         _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    if (__cntrl_)
-        __cntrl_->__add_shared();
-}
-
-template<class _Tp>
-inline
-shared_ptr<_Tp>::shared_ptr(shared_ptr&& __r) _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    __r.__ptr_ = nullptr;
-    __r.__cntrl_ = nullptr;
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-shared_ptr<_Tp>::shared_ptr(shared_ptr<_Yp>&& __r,
-                            typename enable_if<__compatible_with<_Yp, element_type>::value, __nat>::type)
-         _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    __r.__ptr_ = nullptr;
-    __r.__cntrl_ = nullptr;
-}
-
-#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
-template<class _Tp>
-template<class _Yp>
-shared_ptr<_Tp>::shared_ptr(auto_ptr<_Yp>&& __r,
-                            typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type)
-    : __ptr_(__r.get())
-{
-    typedef __shared_ptr_pointer<_Yp*, default_delete<_Yp>, allocator<_Yp> > _CntrlBlk;
-    __cntrl_ = new _CntrlBlk(__r.get(), default_delete<_Yp>(), allocator<_Yp>());
-    __enable_weak_this(__r.get(), __r.get());
-    __r.release();
-}
-#endif
-
-template<class _Tp>
-template <class _Yp, class _Dp>
-shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp>&& __r,
-                            typename enable_if
-                            <
-                                !is_lvalue_reference<_Dp>::value &&
-                                is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
-                                __nat
-                            >::type)
-    : __ptr_(__r.get())
-{
-#if _LIBCPP_STD_VER > 11
-    if (__ptr_ == nullptr)
-        __cntrl_ = nullptr;
-    else
-#endif
-    {
-        typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
-        typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer, _Dp, _AllocT > _CntrlBlk;
-        __cntrl_ = new _CntrlBlk(__r.get(), __r.get_deleter(), _AllocT());
-        __enable_weak_this(__r.get(), __r.get());
-    }
-    __r.release();
-}
-
-template<class _Tp>
-template <class _Yp, class _Dp>
-shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp>&& __r,
-                            typename enable_if
-                            <
-                                is_lvalue_reference<_Dp>::value &&
-                                is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value,
-                                __nat
-                            >::type)
-    : __ptr_(__r.get())
-{
-#if _LIBCPP_STD_VER > 11
-    if (__ptr_ == nullptr)
-        __cntrl_ = nullptr;
-    else
-#endif
-    {
-        typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
-        typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer,
-                                     reference_wrapper<typename remove_reference<_Dp>::type>,
-                                     _AllocT > _CntrlBlk;
-        __cntrl_ = new _CntrlBlk(__r.get(), _VSTD::ref(__r.get_deleter()), _AllocT());
-        __enable_weak_this(__r.get(), __r.get());
-    }
-    __r.release();
-}
-
-template<class _Tp>
-shared_ptr<_Tp>::~shared_ptr()
-{
-    if (__cntrl_)
-        __cntrl_->__release_shared();
-}
-
-template<class _Tp>
-inline
-shared_ptr<_Tp>&
-shared_ptr<_Tp>::operator=(const shared_ptr& __r) _NOEXCEPT
-{
-    shared_ptr(__r).swap(*this);
-    return *this;
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-typename enable_if
-<
-    __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
-    shared_ptr<_Tp>&
->::type
-shared_ptr<_Tp>::operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT
-{
-    shared_ptr(__r).swap(*this);
-    return *this;
-}
-
-template<class _Tp>
-inline
-shared_ptr<_Tp>&
-shared_ptr<_Tp>::operator=(shared_ptr&& __r) _NOEXCEPT
-{
-    shared_ptr(_VSTD::move(__r)).swap(*this);
-    return *this;
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-typename enable_if
-<
-    __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
-    shared_ptr<_Tp>&
->::type
-shared_ptr<_Tp>::operator=(shared_ptr<_Yp>&& __r)
-{
-    shared_ptr(_VSTD::move(__r)).swap(*this);
-    return *this;
-}
-
-#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
-template<class _Tp>
-template<class _Yp>
-inline
-typename enable_if
-<
-    !is_array<_Yp>::value &&
-    is_convertible<_Yp*, typename shared_ptr<_Tp>::element_type*>::value,
-    shared_ptr<_Tp>
->::type&
-shared_ptr<_Tp>::operator=(auto_ptr<_Yp>&& __r)
-{
-    shared_ptr(_VSTD::move(__r)).swap(*this);
-    return *this;
-}
-#endif
-
-template<class _Tp>
-template <class _Yp, class _Dp>
-inline
-typename enable_if
-<
-    is_convertible<typename unique_ptr<_Yp, _Dp>::pointer,
-                   typename shared_ptr<_Tp>::element_type*>::value,
-    shared_ptr<_Tp>&
->::type
-shared_ptr<_Tp>::operator=(unique_ptr<_Yp, _Dp>&& __r)
-{
-    shared_ptr(_VSTD::move(__r)).swap(*this);
-    return *this;
-}
-
-template<class _Tp>
-inline
-void
-shared_ptr<_Tp>::swap(shared_ptr& __r) _NOEXCEPT
-{
-    _VSTD::swap(__ptr_, __r.__ptr_);
-    _VSTD::swap(__cntrl_, __r.__cntrl_);
-}
-
-template<class _Tp>
-inline
-void
-shared_ptr<_Tp>::reset() _NOEXCEPT
-{
-    shared_ptr().swap(*this);
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-typename enable_if
-<
-    __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
-    void
->::type
-shared_ptr<_Tp>::reset(_Yp* __p)
-{
-    shared_ptr(__p).swap(*this);
-}
-
-template<class _Tp>
-template<class _Yp, class _Dp>
-inline
-typename enable_if
-<
-    __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
-    void
->::type
-shared_ptr<_Tp>::reset(_Yp* __p, _Dp __d)
-{
-    shared_ptr(__p, __d).swap(*this);
-}
-
-template<class _Tp>
-template<class _Yp, class _Dp, class _Alloc>
-inline
-typename enable_if
-<
-    __compatible_with<_Yp, typename shared_ptr<_Tp>::element_type>::value,
-    void
->::type
-shared_ptr<_Tp>::reset(_Yp* __p, _Dp __d, _Alloc __a)
-{
-    shared_ptr(__p, __d, __a).swap(*this);
-}
-
-//
-// std::allocate_shared and std::make_shared
-//
-template<class _Tp, class _Alloc, class ..._Args, class = _EnableIf<!is_array<_Tp>::value> >
-_LIBCPP_HIDE_FROM_ABI
-shared_ptr<_Tp> allocate_shared(const _Alloc& __a, _Args&& ...__args)
-{
-    using _ControlBlock = __shared_ptr_emplace<_Tp, _Alloc>;
-    using _ControlBlockAllocator = typename __allocator_traits_rebind<_Alloc, _ControlBlock>::type;
-    __allocation_guard<_ControlBlockAllocator> __guard(__a, 1);
-    ::new ((void*)_VSTD::addressof(*__guard.__get())) _ControlBlock(__a, _VSTD::forward<_Args>(__args)...);
-    auto __control_block = __guard.__release_ptr();
-    return shared_ptr<_Tp>::__create_with_control_block((*__control_block).__get_elem(), _VSTD::addressof(*__control_block));
-}
-
-template<class _Tp, class ..._Args, class = _EnableIf<!is_array<_Tp>::value> >
-_LIBCPP_HIDE_FROM_ABI
-shared_ptr<_Tp> make_shared(_Args&& ...__args)
-{
-    return _VSTD::allocate_shared<_Tp>(allocator<_Tp>(), _VSTD::forward<_Args>(__args)...);
-}
-
-template<class _Tp, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator==(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
-{
-    return __x.get() == __y.get();
-}
-
-template<class _Tp, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator!=(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
-{
-    return !(__x == __y);
-}
-
-template<class _Tp, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator<(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
-{
-#if _LIBCPP_STD_VER <= 11
-    typedef typename common_type<_Tp*, _Up*>::type _Vp;
-    return less<_Vp>()(__x.get(), __y.get());
-#else
-    return less<>()(__x.get(), __y.get());
-#endif
-
-}
-
-template<class _Tp, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator>(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
-{
-    return __y < __x;
-}
-
-template<class _Tp, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator<=(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
-{
-    return !(__y < __x);
-}
-
-template<class _Tp, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator>=(const shared_ptr<_Tp>& __x, const shared_ptr<_Up>& __y) _NOEXCEPT
-{
-    return !(__x < __y);
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator==(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
-{
-    return !__x;
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator==(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
-{
-    return !__x;
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator!=(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
-{
-    return static_cast<bool>(__x);
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator!=(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
-{
-    return static_cast<bool>(__x);
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator<(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
-{
-    return less<_Tp*>()(__x.get(), nullptr);
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator<(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
-{
-    return less<_Tp*>()(nullptr, __x.get());
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator>(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
-{
-    return nullptr < __x;
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator>(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
-{
-    return __x < nullptr;
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator<=(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
-{
-    return !(nullptr < __x);
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator<=(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
-{
-    return !(__x < nullptr);
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator>=(const shared_ptr<_Tp>& __x, nullptr_t) _NOEXCEPT
-{
-    return !(__x < nullptr);
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-operator>=(nullptr_t, const shared_ptr<_Tp>& __x) _NOEXCEPT
-{
-    return !(nullptr < __x);
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-swap(shared_ptr<_Tp>& __x, shared_ptr<_Tp>& __y) _NOEXCEPT
-{
-    __x.swap(__y);
-}
-
-template<class _Tp, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY
-shared_ptr<_Tp>
-static_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
-{
-    return shared_ptr<_Tp>(__r,
-                           static_cast<
-                               typename shared_ptr<_Tp>::element_type*>(__r.get()));
-}
-
-template<class _Tp, class _Up>
-inline _LIBCPP_INLINE_VISIBILITY
-shared_ptr<_Tp>
-dynamic_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
-{
-    typedef typename shared_ptr<_Tp>::element_type _ET;
-    _ET* __p = dynamic_cast<_ET*>(__r.get());
-    return __p ? shared_ptr<_Tp>(__r, __p) : shared_ptr<_Tp>();
-}
-
-template<class _Tp, class _Up>
-shared_ptr<_Tp>
-const_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
-{
-    typedef typename shared_ptr<_Tp>::element_type _RTp;
-    return shared_ptr<_Tp>(__r, const_cast<_RTp*>(__r.get()));
-}
-
-template<class _Tp, class _Up>
-shared_ptr<_Tp>
-reinterpret_pointer_cast(const shared_ptr<_Up>& __r) _NOEXCEPT
-{
-    return shared_ptr<_Tp>(__r,
-                           reinterpret_cast<
-                               typename shared_ptr<_Tp>::element_type*>(__r.get()));
-}
-
-#ifndef _LIBCPP_NO_RTTI
-
-template<class _Dp, class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-_Dp*
-get_deleter(const shared_ptr<_Tp>& __p) _NOEXCEPT
-{
-    return __p.template __get_deleter<_Dp>();
-}
-
-#endif  // _LIBCPP_NO_RTTI
-
-template<class _Tp>
-class _LIBCPP_SHARED_PTR_TRIVIAL_ABI _LIBCPP_TEMPLATE_VIS weak_ptr
-{
-public:
-    typedef _Tp element_type;
-private:
-    element_type*        __ptr_;
-    __shared_weak_count* __cntrl_;
-
-public:
-    _LIBCPP_INLINE_VISIBILITY
-    _LIBCPP_CONSTEXPR weak_ptr() _NOEXCEPT;
-    template<class _Yp> _LIBCPP_INLINE_VISIBILITY weak_ptr(shared_ptr<_Yp> const& __r,
-                   typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type = 0)
-                        _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    weak_ptr(weak_ptr const& __r) _NOEXCEPT;
-    template<class _Yp> _LIBCPP_INLINE_VISIBILITY weak_ptr(weak_ptr<_Yp> const& __r,
-                   typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type = 0)
-                         _NOEXCEPT;
-
-    _LIBCPP_INLINE_VISIBILITY
-    weak_ptr(weak_ptr&& __r) _NOEXCEPT;
-    template<class _Yp> _LIBCPP_INLINE_VISIBILITY weak_ptr(weak_ptr<_Yp>&& __r,
-                   typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type = 0)
-                         _NOEXCEPT;
-    ~weak_ptr();
-
-    _LIBCPP_INLINE_VISIBILITY
-    weak_ptr& operator=(weak_ptr const& __r) _NOEXCEPT;
-    template<class _Yp>
-        typename enable_if
-        <
-            is_convertible<_Yp*, element_type*>::value,
-            weak_ptr&
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        operator=(weak_ptr<_Yp> const& __r) _NOEXCEPT;
-
-    _LIBCPP_INLINE_VISIBILITY
-    weak_ptr& operator=(weak_ptr&& __r) _NOEXCEPT;
-    template<class _Yp>
-        typename enable_if
-        <
-            is_convertible<_Yp*, element_type*>::value,
-            weak_ptr&
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        operator=(weak_ptr<_Yp>&& __r) _NOEXCEPT;
-
-    template<class _Yp>
-        typename enable_if
-        <
-            is_convertible<_Yp*, element_type*>::value,
-            weak_ptr&
-        >::type
-        _LIBCPP_INLINE_VISIBILITY
-        operator=(shared_ptr<_Yp> const& __r) _NOEXCEPT;
-
-    _LIBCPP_INLINE_VISIBILITY
-    void swap(weak_ptr& __r) _NOEXCEPT;
-    _LIBCPP_INLINE_VISIBILITY
-    void reset() _NOEXCEPT;
-
-    _LIBCPP_INLINE_VISIBILITY
-    long use_count() const _NOEXCEPT
-        {return __cntrl_ ? __cntrl_->use_count() : 0;}
-    _LIBCPP_INLINE_VISIBILITY
-    bool expired() const _NOEXCEPT
-        {return __cntrl_ == nullptr || __cntrl_->use_count() == 0;}
-    shared_ptr<_Tp> lock() const _NOEXCEPT;
-    template<class _Up>
-        _LIBCPP_INLINE_VISIBILITY
-        bool owner_before(const shared_ptr<_Up>& __r) const _NOEXCEPT
-        {return __cntrl_ < __r.__cntrl_;}
-    template<class _Up>
-        _LIBCPP_INLINE_VISIBILITY
-        bool owner_before(const weak_ptr<_Up>& __r) const _NOEXCEPT
-        {return __cntrl_ < __r.__cntrl_;}
-
-    template <class _Up> friend class _LIBCPP_TEMPLATE_VIS weak_ptr;
-    template <class _Up> friend class _LIBCPP_TEMPLATE_VIS shared_ptr;
-};
-
-#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
-template<class _Tp>
-weak_ptr(shared_ptr<_Tp>) -> weak_ptr<_Tp>;
-#endif
-
-template<class _Tp>
-inline
-_LIBCPP_CONSTEXPR
-weak_ptr<_Tp>::weak_ptr() _NOEXCEPT
-    : __ptr_(nullptr),
-      __cntrl_(nullptr)
-{
-}
-
-template<class _Tp>
-inline
-weak_ptr<_Tp>::weak_ptr(weak_ptr const& __r) _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    if (__cntrl_)
-        __cntrl_->__add_weak();
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-weak_ptr<_Tp>::weak_ptr(shared_ptr<_Yp> const& __r,
-                        typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type)
-                         _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    if (__cntrl_)
-        __cntrl_->__add_weak();
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-weak_ptr<_Tp>::weak_ptr(weak_ptr<_Yp> const& __r,
-                        typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type)
-         _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    if (__cntrl_)
-        __cntrl_->__add_weak();
-}
-
-template<class _Tp>
-inline
-weak_ptr<_Tp>::weak_ptr(weak_ptr&& __r) _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    __r.__ptr_ = nullptr;
-    __r.__cntrl_ = nullptr;
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-weak_ptr<_Tp>::weak_ptr(weak_ptr<_Yp>&& __r,
-                        typename enable_if<is_convertible<_Yp*, _Tp*>::value, __nat*>::type)
-         _NOEXCEPT
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_)
-{
-    __r.__ptr_ = nullptr;
-    __r.__cntrl_ = nullptr;
-}
-
-template<class _Tp>
-weak_ptr<_Tp>::~weak_ptr()
-{
-    if (__cntrl_)
-        __cntrl_->__release_weak();
-}
-
-template<class _Tp>
-inline
-weak_ptr<_Tp>&
-weak_ptr<_Tp>::operator=(weak_ptr const& __r) _NOEXCEPT
-{
-    weak_ptr(__r).swap(*this);
-    return *this;
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-typename enable_if
-<
-    is_convertible<_Yp*, _Tp*>::value,
-    weak_ptr<_Tp>&
->::type
-weak_ptr<_Tp>::operator=(weak_ptr<_Yp> const& __r) _NOEXCEPT
-{
-    weak_ptr(__r).swap(*this);
-    return *this;
-}
-
-template<class _Tp>
-inline
-weak_ptr<_Tp>&
-weak_ptr<_Tp>::operator=(weak_ptr&& __r) _NOEXCEPT
-{
-    weak_ptr(_VSTD::move(__r)).swap(*this);
-    return *this;
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-typename enable_if
-<
-    is_convertible<_Yp*, _Tp*>::value,
-    weak_ptr<_Tp>&
->::type
-weak_ptr<_Tp>::operator=(weak_ptr<_Yp>&& __r) _NOEXCEPT
-{
-    weak_ptr(_VSTD::move(__r)).swap(*this);
-    return *this;
-}
-
-template<class _Tp>
-template<class _Yp>
-inline
-typename enable_if
-<
-    is_convertible<_Yp*, _Tp*>::value,
-    weak_ptr<_Tp>&
->::type
-weak_ptr<_Tp>::operator=(shared_ptr<_Yp> const& __r) _NOEXCEPT
-{
-    weak_ptr(__r).swap(*this);
-    return *this;
-}
-
-template<class _Tp>
-inline
-void
-weak_ptr<_Tp>::swap(weak_ptr& __r) _NOEXCEPT
-{
-    _VSTD::swap(__ptr_, __r.__ptr_);
-    _VSTD::swap(__cntrl_, __r.__cntrl_);
-}
-
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-swap(weak_ptr<_Tp>& __x, weak_ptr<_Tp>& __y) _NOEXCEPT
-{
-    __x.swap(__y);
-}
-
-template<class _Tp>
-inline
-void
-weak_ptr<_Tp>::reset() _NOEXCEPT
-{
-    weak_ptr().swap(*this);
-}
-
-template<class _Tp>
-template<class _Yp>
-shared_ptr<_Tp>::shared_ptr(const weak_ptr<_Yp>& __r,
-                            typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type)
-    : __ptr_(__r.__ptr_),
-      __cntrl_(__r.__cntrl_ ? __r.__cntrl_->lock() : __r.__cntrl_)
-{
-    if (__cntrl_ == nullptr)
-        __throw_bad_weak_ptr();
-}
-
-template<class _Tp>
-shared_ptr<_Tp>
-weak_ptr<_Tp>::lock() const _NOEXCEPT
-{
-    shared_ptr<_Tp> __r;
-    __r.__cntrl_ = __cntrl_ ? __cntrl_->lock() : __cntrl_;
-    if (__r.__cntrl_)
-        __r.__ptr_ = __ptr_;
-    return __r;
-}
-
-#if _LIBCPP_STD_VER > 14
-template <class _Tp = void> struct owner_less;
-#else
-template <class _Tp> struct owner_less;
-#endif
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS owner_less<shared_ptr<_Tp> >
-    : binary_function<shared_ptr<_Tp>, shared_ptr<_Tp>, bool>
-{
-    typedef bool result_type;
-    _LIBCPP_INLINE_VISIBILITY
-    bool operator()(shared_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const _NOEXCEPT
-        {return __x.owner_before(__y);}
-    _LIBCPP_INLINE_VISIBILITY
-    bool operator()(shared_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const _NOEXCEPT
-        {return __x.owner_before(__y);}
-    _LIBCPP_INLINE_VISIBILITY
-    bool operator()(  weak_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const _NOEXCEPT
-        {return __x.owner_before(__y);}
-};
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS owner_less<weak_ptr<_Tp> >
-    : binary_function<weak_ptr<_Tp>, weak_ptr<_Tp>, bool>
-{
-    typedef bool result_type;
-    _LIBCPP_INLINE_VISIBILITY
-    bool operator()(  weak_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const _NOEXCEPT
-        {return __x.owner_before(__y);}
-    _LIBCPP_INLINE_VISIBILITY
-    bool operator()(shared_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const _NOEXCEPT
-        {return __x.owner_before(__y);}
-    _LIBCPP_INLINE_VISIBILITY
-    bool operator()(  weak_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const _NOEXCEPT
-        {return __x.owner_before(__y);}
-};
-
-#if _LIBCPP_STD_VER > 14
-template <>
-struct _LIBCPP_TEMPLATE_VIS owner_less<void>
-{
-    template <class _Tp, class _Up>
-    _LIBCPP_INLINE_VISIBILITY
-    bool operator()( shared_ptr<_Tp> const& __x, shared_ptr<_Up> const& __y) const _NOEXCEPT
-        {return __x.owner_before(__y);}
-    template <class _Tp, class _Up>
-    _LIBCPP_INLINE_VISIBILITY
-    bool operator()( shared_ptr<_Tp> const& __x,   weak_ptr<_Up> const& __y) const _NOEXCEPT
-        {return __x.owner_before(__y);}
-    template <class _Tp, class _Up>
-    _LIBCPP_INLINE_VISIBILITY
-    bool operator()(   weak_ptr<_Tp> const& __x, shared_ptr<_Up> const& __y) const _NOEXCEPT
-        {return __x.owner_before(__y);}
-    template <class _Tp, class _Up>
-    _LIBCPP_INLINE_VISIBILITY
-    bool operator()(   weak_ptr<_Tp> const& __x,   weak_ptr<_Up> const& __y) const _NOEXCEPT
-        {return __x.owner_before(__y);}
-    typedef void is_transparent;
-};
-#endif
-
-template<class _Tp>
-class _LIBCPP_TEMPLATE_VIS enable_shared_from_this
-{
-    mutable weak_ptr<_Tp> __weak_this_;
-protected:
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-    enable_shared_from_this() _NOEXCEPT {}
-    _LIBCPP_INLINE_VISIBILITY
-    enable_shared_from_this(enable_shared_from_this const&) _NOEXCEPT {}
-    _LIBCPP_INLINE_VISIBILITY
-    enable_shared_from_this& operator=(enable_shared_from_this const&) _NOEXCEPT
-        {return *this;}
-    _LIBCPP_INLINE_VISIBILITY
-    ~enable_shared_from_this() {}
-public:
-    _LIBCPP_INLINE_VISIBILITY
-    shared_ptr<_Tp> shared_from_this()
-        {return shared_ptr<_Tp>(__weak_this_);}
-    _LIBCPP_INLINE_VISIBILITY
-    shared_ptr<_Tp const> shared_from_this() const
-        {return shared_ptr<const _Tp>(__weak_this_);}
-
-#if _LIBCPP_STD_VER > 14
-    _LIBCPP_INLINE_VISIBILITY
-    weak_ptr<_Tp> weak_from_this() _NOEXCEPT
-       { return __weak_this_; }
-
-    _LIBCPP_INLINE_VISIBILITY
-    weak_ptr<const _Tp> weak_from_this() const _NOEXCEPT
-        { return __weak_this_; }
-#endif // _LIBCPP_STD_VER > 14
-
-    template <class _Up> friend class shared_ptr;
-};
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS hash<shared_ptr<_Tp> >
-{
-    typedef shared_ptr<_Tp>      argument_type;
-    typedef size_t               result_type;
-
-    _LIBCPP_INLINE_VISIBILITY
-    result_type operator()(const argument_type& __ptr) const _NOEXCEPT
-    {
-        return hash<typename shared_ptr<_Tp>::element_type*>()(__ptr.get());
-    }
-};
-
-template<class _CharT, class _Traits, class _Yp>
-inline _LIBCPP_INLINE_VISIBILITY
-basic_ostream<_CharT, _Traits>&
-operator<<(basic_ostream<_CharT, _Traits>& __os, shared_ptr<_Yp> const& __p);
-
-
-#if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
-
-class _LIBCPP_TYPE_VIS __sp_mut
-{
-    void* __lx;
-public:
-    void lock() _NOEXCEPT;
-    void unlock() _NOEXCEPT;
-
-private:
-    _LIBCPP_CONSTEXPR __sp_mut(void*) _NOEXCEPT;
-    __sp_mut(const __sp_mut&);
-    __sp_mut& operator=(const __sp_mut&);
-
-    friend _LIBCPP_FUNC_VIS __sp_mut& __get_sp_mut(const void*);
-};
-
-_LIBCPP_FUNC_VIS _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
-__sp_mut& __get_sp_mut(const void*);
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-bool
-atomic_is_lock_free(const shared_ptr<_Tp>*)
-{
-    return false;
-}
-
-template <class _Tp>
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
-shared_ptr<_Tp>
-atomic_load(const shared_ptr<_Tp>* __p)
-{
-    __sp_mut& __m = __get_sp_mut(__p);
-    __m.lock();
-    shared_ptr<_Tp> __q = *__p;
-    __m.unlock();
-    return __q;
-}
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
-shared_ptr<_Tp>
-atomic_load_explicit(const shared_ptr<_Tp>* __p, memory_order)
-{
-    return atomic_load(__p);
-}
-
-template <class _Tp>
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
-void
-atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
-{
-    __sp_mut& __m = __get_sp_mut(__p);
-    __m.lock();
-    __p->swap(__r);
-    __m.unlock();
-}
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
-void
-atomic_store_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order)
-{
-    atomic_store(__p, __r);
-}
-
-template <class _Tp>
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
-shared_ptr<_Tp>
-atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
-{
-    __sp_mut& __m = __get_sp_mut(__p);
-    __m.lock();
-    __p->swap(__r);
-    __m.unlock();
-    return __r;
-}
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
-shared_ptr<_Tp>
-atomic_exchange_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order)
-{
-    return atomic_exchange(__p, __r);
-}
-
-template <class _Tp>
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
-bool
-atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w)
-{
-    shared_ptr<_Tp> __temp;
-    __sp_mut& __m = __get_sp_mut(__p);
-    __m.lock();
-    if (__p->__owner_equivalent(*__v))
-    {
-        _VSTD::swap(__temp, *__p);
-        *__p = __w;
-        __m.unlock();
-        return true;
-    }
-    _VSTD::swap(__temp, *__v);
-    *__v = *__p;
-    __m.unlock();
-    return false;
-}
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
-bool
-atomic_compare_exchange_weak(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_ptr<_Tp> __w)
-{
-    return atomic_compare_exchange_strong(__p, __v, __w);
-}
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
-bool
-atomic_compare_exchange_strong_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v,
-                                        shared_ptr<_Tp> __w, memory_order, memory_order)
-{
-    return atomic_compare_exchange_strong(__p, __v, __w);
-}
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
-bool
-atomic_compare_exchange_weak_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v,
-                                      shared_ptr<_Tp> __w, memory_order, memory_order)
-{
-    return atomic_compare_exchange_weak(__p, __v, __w);
-}
-
-#endif  // !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
-
-//enum class
-#if defined(_LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE)
-# ifndef _LIBCPP_CXX03_LANG
-enum class pointer_safety : unsigned char {
-  relaxed,
-  preferred,
-  strict
-};
-# endif
-#else
-struct _LIBCPP_TYPE_VIS pointer_safety
-{
-    enum __lx
-    {
-        relaxed,
-        preferred,
-        strict
-    };
-
-    __lx __v_;
-
-    _LIBCPP_INLINE_VISIBILITY
-    pointer_safety() : __v_() {}
-
-    _LIBCPP_INLINE_VISIBILITY
-    pointer_safety(__lx __v) : __v_(__v) {}
-    _LIBCPP_INLINE_VISIBILITY
-    operator int() const {return __v_;}
-};
-#endif
-
-#if !defined(_LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE) && \
-    defined(_LIBCPP_BUILDING_LIBRARY)
-_LIBCPP_FUNC_VIS pointer_safety get_pointer_safety() _NOEXCEPT;
-#else
-// This function is only offered in C++03 under ABI v1.
-# if !defined(_LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE) || !defined(_LIBCPP_CXX03_LANG)
-inline _LIBCPP_INLINE_VISIBILITY
-pointer_safety get_pointer_safety() _NOEXCEPT {
-  return pointer_safety::relaxed;
-}
-# endif
-#endif
-
-
-_LIBCPP_FUNC_VIS void declare_reachable(void* __p);
-_LIBCPP_FUNC_VIS void declare_no_pointers(char* __p, size_t __n);
-_LIBCPP_FUNC_VIS void undeclare_no_pointers(char* __p, size_t __n);
-_LIBCPP_FUNC_VIS void* __undeclare_reachable(void* __p);
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-_Tp*
-undeclare_reachable(_Tp* __p)
-{
-    return static_cast<_Tp*>(__undeclare_reachable(__p));
-}
-
 _LIBCPP_FUNC_VIS void* align(size_t __align, size_t __sz, void*& __ptr, size_t& __space);
 
 // --- Helper for container swap --
 template <typename _Alloc>
 _LIBCPP_INLINE_VISIBILITY
 void __swap_allocator(_Alloc & __a1, _Alloc & __a2, true_type)
 #if _LIBCPP_STD_VER >= 14
     _NOEXCEPT

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.obs/op_arrow.fail.cpp

 struct Foo {
   void call() {}
 };
 
 int main(int, char**) {
   // Check that we get a static assertion when we try to use the bracket
   // operator on shared_ptr<T> when T is not an array type.
   const std::shared_ptr<Foo[]> p1;
-  (void)p1
-      ->call(); // expected-error@memory:* {{std::shared_ptr<T>::operator-> is only valid when T is not an array type.}}
+  (void)p1->call(); // expected-error@*:* {{std::shared_ptr<T>::operator-> is only valid when T is not an array type.}}
   const std::shared_ptr<Foo[4]> p2;
-  (void)p2
-      ->call(); // expected-error@memory:* {{std::shared_ptr<T>::operator-> is only valid when T is not an array type.}}
+  (void)p2->call(); // expected-error@*:* {{std::shared_ptr<T>::operator-> is only valid when T is not an array type.}}
   return 0;
 }

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.obs/op_bracket.fail.cpp

 
 #include <memory>
 #include <cassert>
 
 int main(int, char**) {
   // Check that we get a static assertion when we try to use the bracket
   // operator on shared_ptr<T> when T is not an array type.
   const std::shared_ptr<int> p;
-  (void)p
-      [0]; // expected-error@memory:* {{std::shared_ptr<T>::operator[] is only valid when T is an array type.}}
+  (void)p[0]; // expected-error@*:* {{std::shared_ptr<T>::operator[] is only valid when T is an array type.}}
   return 0;
 }