Merge clang, llvm, lld, lldb, compiler-rt and libc++ 5.0.0 release.

MFC r309126 (by emaste):

  Correct lld llvm-tblgen dependency file name

MFC r309169:

  Get rid of separate Subversion mergeinfo properties for llvm-dwarfdump
  and llvm-lto.  The mergeinfo confuses Subversion enormously, and these
  directories will just use the mergeinfo for llvm itself.

MFC r312765:

  Pull in r276136 from upstream llvm trunk (by Wei Mi):

    Use ValueOffsetPair to enhance value reuse during SCEV expansion.

    In D12090, the ExprValueMap was added to reuse existing value during
    SCEV expansion. However, const folding and sext/zext distribution can
    make the reuse still difficult.

    A simplified case is: suppose we know S1 expands to V1 in
    ExprValueMap, and
      S1 = S2 + C_a
      S3 = S2 + C_b
    where C_a and C_b are different SCEVConstants. Then we'd like to
    expand S3 as V1 - C_a + C_b instead of expanding S2 literally. It is
    helpful when S2 is a complex SCEV expr and S2 has no entry in
    ExprValueMap, which is usually caused by the fact that S3 is
    generated from S1 after const folding.

    In order to do that, we represent ExprValueMap as a mapping from SCEV
    to ValueOffsetPair. We will save both S1->{V1, 0} and S2->{V1, C_a}
    into the ExprValueMap when we create SCEV for V1. When S3 is
    expanded, it will first expand S2 to V1 - C_a because of S2->{V1,
    C_a} in the map, then expand S3 to V1 - C_a + C_b.

    Differential Revision: https://reviews.llvm.org/D21313

  This should fix assertion failures when building OpenCV >= 3.1.

  PR:		215649

MFC r312831:

  Revert r312765 for now, since it causes assertions when building
  lang/spidermonkey24.

  Reported by:	antoine
  PR:		215649

MFC r316511 (by jhb):

  Add an implementation of __ffssi2() derived from __ffsdi2().

  Newer versions of GCC include an __ffssi2() symbol in libgcc and the
  compiler can emit calls to it in generated code.  This is true for at
  least GCC 6.2 when compiling world for mips and mips64.

  Reviewed by:	jmallett, dim
  Sponsored by:	DARPA / AFRL
  Differential Revision:	https://reviews.freebsd.org/D10086

MFC r318601 (by adrian):

  [libcompiler-rt] add bswapdi2/bswapsi2

  This is required for mips gcc 6.3 userland to build/run.

  Reviewed by:	emaste, dim
  Approved by:	emaste
  Differential Revision:	https://reviews.freebsd.org/D10838

MFC r318884 (by emaste):

  lldb: map TRAP_CAP to a trace trap

  In the absense of a more specific handler for TRAP_CAP (generated by
  ENOTCAPABLE or ECAPMODE while in capability mode) treat it as a trace
  trap.

  Example usage (testing the bug in PR219173):

  % proccontrol -m trapcap lldb usr.bin/hexdump/obj/hexdump -- -Cv -s 1 /bin/ls
  ...
  (lldb) run
  Process 12980 launching
  Process 12980 launched: '.../usr.bin/hexdump/obj/hexdump' (x86_64)
  Process 12980 stopped
  * thread #1, stop reason = trace
      frame #0: 0x0000004b80c65f1a libc.so.7`__sys_lseek + 10
  ...

  In the future we should have LLDB control the trapcap procctl itself
  (as it does with ASLR), as well as report a specific stop reason.
  This change eliminates an assertion failure from LLDB for now.

MFC r319796:

  Remove a few unneeded files from libllvm, libclang and liblldb.

MFC r319885 (by emaste):

  lld: ELF: Fix ICF crash on absolute symbol relocations.

  If two sections contained relocations to absolute symbols with the same
  value we would crash when trying to access their sections. Add a check that
  both symbols point to sections before accessing their sections, and treat
  absolute symbols as equal if their values are equal.

  Obtained from:	LLD commit r292578

MFC r319918:

  Revert r319796 for now, it can cause undefined references when linking
  in some circumstances.

  Reported by:	Shawn Webb <shawn.webb@hardenedbsd.org>

MFC r319957 (by emaste):

  lld: Add armelf emulation mode

  Obtained from:	LLD r305375

MFC r321369:

  Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
  5.0.0 (trunk r308421).  Upstream has branched for the 5.0.0 release,
  which should be in about a month.  Please report bugs and regressions,
  so we can get them into the release.

  Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
  support to build; see UPDATING for more information.

MFC r321420:

  Add a few more object files to liblldb, which should solve errors when
  linking the lldb executable in some cases.  In particular, when the
  -ffunction-sections -fdata-sections options are turned off, or
  ineffective.

  Reported by:	Shawn Webb, Mark Millard

MFC r321433:

  Cleanup stale Options.inc files from the previous libllvm build for
  clang 4.0.0.  Otherwise, these can get included before the two newly
  generated ones (which are different) for clang 5.0.0.

  Reported by:	Mark Millard

MFC r321439 (by bdrewery):

  Move llvm Options.inc hack from r321433 for NO_CLEAN to lib/clang/libllvm.

  The files are only ever generated to .OBJDIR, not to WORLDTMP (as a
  sysroot) and are only ever included from a compilation.  So using
  a beforebuild target here removes the file before the compilation
  tries to include it.

MFC r321664:

  Pull in r308891 from upstream llvm trunk (by Benjamin Kramer):

    [CodeGenPrepare] Cut off FindAllMemoryUses if there are too many uses.

    This avoids excessive compile time. The case I'm looking at is
    Function.cpp from an old version of LLVM that still had the giant
    memcmp string matcher in it. Before r308322 this compiled in about 2
    minutes, after it, clang takes infinite* time to compile it. With
    this patch we're at 5 min, which is still bad but this is a
    pathological case.

    The cut off at 20 uses was chosen by looking at other cut-offs in LLVM
    for user scanning. It's probably too high, but does the job and is
    very unlikely to regress anything.

    Fixes PR33900.

    * I'm impatient and aborted after 15 minutes, on the bug report it was
      killed after 2h.

  Pull in r308986 from upstream llvm trunk (by Simon Pilgrim):

    [X86][CGP] Reduce memcmp() expansion to 2 load pairs (PR33914)

    D35067/rL308322 attempted to support up to 4 load pairs for memcmp
    inlining which resulted in regressions for some optimized libc memcmp
    implementations (PR33914).

    Until we can match these more optimal cases, this patch reduces the
    memcmp expansion to a maximum of 2 load pairs (which matches what we
    do for -Os).

    This patch should be considered for the 5.0.0 release branch as well

    Differential Revision: https://reviews.llvm.org/D35830

  These fix a hang (or extremely long compile time) when building older
  LLVM ports.

  Reported by:    antoine
  PR:             219139

MFC r321719:

  Pull in r309503 from upstream clang trunk (by Richard Smith):

    PR33902: Invalidate line number cache when adding more text to
    existing buffer.

    This led to crashes as the line number cache would report a bogus
    line number for a line of code, and we'd try to find a nonexistent
    column within the line when printing diagnostics.

  This fixes an assertion when building the graphics/champlain port.

  Reported by:	antoine, kwm
  PR:		219139

MFC r321723:

  Upgrade our copies of clang, llvm, lld and lldb to r309439 from the
  upstream release_50 branch.  This is just after upstream's 5.0.0-rc1.

MFC r322320:

  Upgrade our copies of clang, llvm and libc++ to r310316 from the
  upstream release_50 branch.

MFC r322326 (by emaste):

  lldb: Make i386-*-freebsd expression work on JIT path

  * Enable i386 ABI creation for freebsd
  * Added an extra argument in ABISysV_i386::PrepareTrivialCall for mmap
    syscall
  * Unlike linux, the last argument of mmap is actually 64-bit(off_t).
    This requires us to push an additional word for the higher order bits.
  * Prior to this change, ktrace dump will show mmap failures due to
    invalid argument coming from the 6th mmap argument.

  Submitted by:	Karnajit Wangkhem
  Differential Revision:	https://reviews.llvm.org/D34776

MFC r322360 (by emaste):

  lldb: Report inferior signals as signals, not exceptions, on FreeBSD

  This is the FreeBSD equivalent of LLVM r238549.

  This serves 2 purposes:

  * LLDB should handle inferior process signals SIGSEGV/SIGILL/SIGBUS/
    SIGFPE the way it is suppose to be handled. Prior to this fix these
    signals will neither create a coredump, nor exit from the debugger
    or work for signal handling scenario.
  * eInvalidCrashReason need not report "unknown crash reason" if we have
    a valid si_signo

  llvm.org/pr23699

  Patch by Karnajit Wangkhem

  Differential Revision:  https://reviews.llvm.org/D35223

  Submitted by:	Karnajit Wangkhem
  Obtained from:	LLVM r310591

MFC r322474 (by emaste):

  lld: Add `-z muldefs` option.

  Obtained from:	LLVM r310757

MFC r322740:

  Upgrade our copies of clang, llvm, lld and libc++ to r311219 from the
  upstream release_50 branch.

MFC r322855:

  Upgrade our copies of clang, llvm, lldb and compiler-rt to r311606 from
  the upstream release_50 branch.

  As of this version, lib/msun's trig test should also work correctly
  again (see bug 220989 for more information).

  PR:		220989

MFC r323112:

  Upgrade our copies of clang, llvm, lldb and compiler-rt to r312293 from
  the upstream release_50 branch.  This corresponds to 5.0.0 rc4.

  As of this version, the cad/stepcode port should now compile in a more
  reasonable time on i386 (see bug 221836 for more information).

  PR:		221836

MFC r323245:

  Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
  5.0.0 release (upstream r312559).

  Release notes for llvm, clang and lld will be available here soon:
  <http://releases.llvm.org/5.0.0/docs/ReleaseNotes.html>
  <http://releases.llvm.org/5.0.0/tools/clang/docs/ReleaseNotes.html>
  <http://releases.llvm.org/5.0.0/tools/lld/docs/ReleaseNotes.html>

  Relnotes:	yes

1 files changed, 994 insertions, 1196 deletions

diff --git a/contrib/libc++/include/memory b/contrib/libc++/include/memory
index 2a25f0e..22706d0 100644
--- a/contrib/libc++/include/memory
+++ b/contrib/libc++/include/memory
@@ -208,10 +208,10 @@ template <class ForwardIterator>
 template <class ForwardIterator, class Size>
  ForwardIterator uninitialized_default_construct_n(ForwardIterator first, Size n);
 
-template <class Y> struct auto_ptr_ref {};
+template <class Y> struct auto_ptr_ref {};      // removed in C++17
 
 template<class X>
-class auto_ptr
+class auto_ptr                                  // removed in C++17
 {
 public:
     typedef X element_type;
@@ -270,7 +270,7 @@ public:
     template <class U, class E>
         unique_ptr(unique_ptr<U, E>&& u) noexcept;
     template <class U>
-        unique_ptr(auto_ptr<U>&& u) noexcept;
+        unique_ptr(auto_ptr<U>&& u) noexcept;       // removed in C++17
 
     // destructor
     ~unique_ptr();
@@ -404,7 +404,7 @@ public:
     shared_ptr(shared_ptr&& r) noexcept;
     template<class Y> shared_ptr(shared_ptr<Y>&& r) noexcept;
     template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
-    template<class Y> shared_ptr(auto_ptr<Y>&& r);
+    template<class Y> shared_ptr(auto_ptr<Y>&& r);          // removed in C++17
     template <class Y, class D> shared_ptr(unique_ptr<Y, D>&& r);
     shared_ptr(nullptr_t) : shared_ptr() { }
 
@@ -416,7 +416,7 @@ public:
     template<class Y> shared_ptr& operator=(const shared_ptr<Y>& r) noexcept;
     shared_ptr& operator=(shared_ptr&& r) noexcept;
     template<class Y> shared_ptr& operator=(shared_ptr<Y>&& r);
-    template<class Y> shared_ptr& operator=(auto_ptr<Y>&& r);
+    template<class Y> shared_ptr& operator=(auto_ptr<Y>&& r); // removed in C++17
     template <class Y, class D> shared_ptr& operator=(unique_ptr<Y, D>&& r);
 
     // modifiers:
@@ -433,8 +433,8 @@ public:
     long use_count() const noexcept;
     bool unique() const noexcept;
     explicit operator bool() const noexcept;
-    template<class U> bool owner_before(shared_ptr<U> const& b) const;
-    template<class U> bool owner_before(weak_ptr<U> const& b) const;
+    template<class U> bool owner_before(shared_ptr<U> const& b) const noexcept;
+    template<class U> bool owner_before(weak_ptr<U> const& b) const noexcept;
 };
 
 // shared_ptr comparisons:
@@ -531,8 +531,8 @@ public:
     long use_count() const noexcept;
     bool expired() const noexcept;
     shared_ptr<T> lock() const noexcept;
-    template<class U> bool owner_before(shared_ptr<U> const& b) const;
-    template<class U> bool owner_before(weak_ptr<U> const& b) const;
+    template<class U> bool owner_before(shared_ptr<U> const& b) const noexcept;
+    template<class U> bool owner_before(weak_ptr<U> const& b) const noexcept;
 };
 
 // weak_ptr specialized algorithms:
@@ -546,9 +546,9 @@ struct owner_less<shared_ptr<T>>
     : binary_function<shared_ptr<T>, shared_ptr<T>, bool>
 {
     typedef bool result_type;
-    bool operator()(shared_ptr<T> const&, shared_ptr<T> const&) const;
-    bool operator()(shared_ptr<T> const&, weak_ptr<T> const&) const;
-    bool operator()(weak_ptr<T> const&, shared_ptr<T> const&) const;
+    bool operator()(shared_ptr<T> const&, shared_ptr<T> const&) const noexcept;
+    bool operator()(shared_ptr<T> const&, weak_ptr<T> const&) const noexcept;
+    bool operator()(weak_ptr<T> const&, shared_ptr<T> const&) const noexcept;
 };
 
 template<class T>
@@ -556,9 +556,24 @@ struct owner_less<weak_ptr<T>>
     : binary_function<weak_ptr<T>, weak_ptr<T>, bool>
 {
     typedef bool result_type;
-    bool operator()(weak_ptr<T> const&, weak_ptr<T> const&) const;
-    bool operator()(shared_ptr<T> const&, weak_ptr<T> const&) const;
-    bool operator()(weak_ptr<T> const&, shared_ptr<T> const&) const;
+    bool operator()(weak_ptr<T> const&, weak_ptr<T> const&) const noexcept;
+    bool operator()(shared_ptr<T> const&, weak_ptr<T> const&) const noexcept;
+    bool operator()(weak_ptr<T> const&, shared_ptr<T> const&) const noexcept;
+};
+
+template <>  // Added in C++14
+struct owner_less<void>
+{
+    template <class _Tp, class _Up>
+    bool operator()( shared_ptr<_Tp> const& __x, shared_ptr<_Up> const& __y) const noexcept;
+    template <class _Tp, class _Up>
+    bool operator()( shared_ptr<_Tp> const& __x,   weak_ptr<_Up> const& __y) const noexcept;
+    template <class _Tp, class _Up>
+    bool operator()(   weak_ptr<_Tp> const& __x, shared_ptr<_Up> const& __y) const noexcept;
+    template <class _Tp, class _Up>
+    bool operator()(   weak_ptr<_Tp> const& __x,   weak_ptr<_Up> const& __y) const noexcept;
+
+    typedef void is_transparent;
 };
 
 template<class T>
@@ -638,17 +653,19 @@ void* align(size_t alignment, size_t size, void*& ptr, size_t& space);
 #include <tuple>
 #include <stdexcept>
 #include <cstring>
-
+#include <cassert>
 #if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
 #  include <atomic>
 #endif
 
-#include <__undef_min_max>
-
 #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>
@@ -703,16 +720,12 @@ public:
 
 // pointer_traits
 
+template <class _Tp, class = void>
+struct __has_element_type : false_type {};
+
 template <class _Tp>
-struct __has_element_type
-{
-private:
-    struct __two {char __lx; char __lxx;};
-    template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::element_type* = 0);
-public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
-};
+struct __has_element_type<_Tp, 
+              typename __void_t<typename _Tp::element_type>::type> : true_type {};
 
 template <class _Ptr, bool = __has_element_type<_Ptr>::value>
 struct __pointer_traits_element_type;
@@ -791,16 +804,12 @@ struct __pointer_traits_element_type<_Sp<_Tp, _A0, _A1, _A2>, false>
 
 #endif  // _LIBCPP_HAS_NO_VARIADICS
 
+template <class _Tp, class = void>
+struct __has_difference_type : false_type {};
+
 template <class _Tp>
-struct __has_difference_type
-{
-private:
-    struct __two {char __lx; char __lxx;};
-    template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::difference_type* = 0);
-public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
-};
+struct __has_difference_type<_Tp, 
+            typename __void_t<typename _Tp::difference_type>::type> : true_type {};
 
 template <class _Ptr, bool = __has_difference_type<_Ptr>::value>
 struct __pointer_traits_difference_type
@@ -981,17 +990,12 @@ struct __rebind_pointer {
 
 // allocator_traits
 
-namespace __has_pointer_type_imp
-{
-    template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::pointer* = 0);
-}
+template <class _Tp, class = void>
+struct __has_pointer_type : false_type {};
 
 template <class _Tp>
-struct __has_pointer_type
-    : public integral_constant<bool, sizeof(__has_pointer_type_imp::__test<_Tp>(0)) == 1>
-{
-};
+struct __has_pointer_type<_Tp, 
+          typename __void_t<typename _Tp::pointer>::type> : true_type {};
 
 namespace __pointer_type_imp
 {
@@ -1016,16 +1020,12 @@ struct __pointer_type
     typedef typename __pointer_type_imp::__pointer_type<_Tp, typename remove_reference<_Dp>::type>::type type;
 };
 
+template <class _Tp, class = void>
+struct __has_const_pointer : false_type {};
+
 template <class _Tp>
-struct __has_const_pointer
-{
-private:
-    struct __two {char __lx; char __lxx;};
-    template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::const_pointer* = 0);
-public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
-};
+struct __has_const_pointer<_Tp, 
+            typename __void_t<typename _Tp::const_pointer>::type> : true_type {};
 
 template <class _Tp, class _Ptr, class _Alloc, bool = __has_const_pointer<_Alloc>::value>
 struct __const_pointer
@@ -1043,16 +1043,12 @@ struct __const_pointer<_Tp, _Ptr, _Alloc, false>
 #endif
 };
 
+template <class _Tp, class = void>
+struct __has_void_pointer : false_type {};
+
 template <class _Tp>
-struct __has_void_pointer
-{
-private:
-    struct __two {char __lx; char __lxx;};
-    template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::void_pointer* = 0);
-public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
-};
+struct __has_void_pointer<_Tp, 
+               typename __void_t<typename _Tp::void_pointer>::type> : true_type {};
 
 template <class _Ptr, class _Alloc, bool = __has_void_pointer<_Alloc>::value>
 struct __void_pointer
@@ -1070,16 +1066,12 @@ struct __void_pointer<_Ptr, _Alloc, false>
 #endif
 };
 
+template <class _Tp, class = void>
+struct __has_const_void_pointer : false_type {};
+
 template <class _Tp>
-struct __has_const_void_pointer
-{
-private:
-    struct __two {char __lx; char __lxx;};
-    template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::const_void_pointer* = 0);
-public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
-};
+struct __has_const_void_pointer<_Tp, 
+            typename __void_t<typename _Tp::const_void_pointer>::type> : true_type {};
 
 template <class _Ptr, class _Alloc, bool = __has_const_void_pointer<_Alloc>::value>
 struct __const_void_pointer
@@ -1113,16 +1105,12 @@ __to_raw_pointer(_Pointer __p) _NOEXCEPT
     return _VSTD::__to_raw_pointer(__p.operator->());
 }
 
+template <class _Tp, class = void>
+struct __has_size_type : false_type {};
+
 template <class _Tp>
-struct __has_size_type
-{
-private:
-    struct __two {char __lx; char __lxx;};
-    template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::size_type* = 0);
-public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
-};
+struct __has_size_type<_Tp,
+               typename __void_t<typename _Tp::size_type>::type> : true_type {};
 
 template <class _Alloc, class _DiffType, bool = __has_size_type<_Alloc>::value>
 struct __size_type
@@ -1136,16 +1124,13 @@ struct __size_type<_Alloc, _DiffType, true>
     typedef typename _Alloc::size_type type;
 };
 
+template <class _Tp, class = void>
+struct __has_propagate_on_container_copy_assignment : false_type {};
+
 template <class _Tp>
-struct __has_propagate_on_container_copy_assignment
-{
-private:
-    struct __two {char __lx; char __lxx;};
-    template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::propagate_on_container_copy_assignment* = 0);
-public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
-};
+struct __has_propagate_on_container_copy_assignment<_Tp,
+    typename __void_t<typename _Tp::propagate_on_container_copy_assignment>::type>
+        : true_type {};
 
 template <class _Alloc, bool = __has_propagate_on_container_copy_assignment<_Alloc>::value>
 struct __propagate_on_container_copy_assignment
@@ -1159,16 +1144,13 @@ struct __propagate_on_container_copy_assignment<_Alloc, true>
     typedef typename _Alloc::propagate_on_container_copy_assignment type;
 };
 
+template <class _Tp, class = void>
+struct __has_propagate_on_container_move_assignment : false_type {};
+
 template <class _Tp>
-struct __has_propagate_on_container_move_assignment
-{
-private:
-    struct __two {char __lx; char __lxx;};
-    template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::propagate_on_container_move_assignment* = 0);
-public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
-};
+struct __has_propagate_on_container_move_assignment<_Tp, 
+           typename __void_t<typename _Tp::propagate_on_container_move_assignment>::type>
+               : true_type {};
 
 template <class _Alloc, bool = __has_propagate_on_container_move_assignment<_Alloc>::value>
 struct __propagate_on_container_move_assignment
@@ -1182,16 +1164,13 @@ struct __propagate_on_container_move_assignment<_Alloc, true>
     typedef typename _Alloc::propagate_on_container_move_assignment type;
 };
 
+template <class _Tp, class = void>
+struct __has_propagate_on_container_swap : false_type {};
+
 template <class _Tp>
-struct __has_propagate_on_container_swap
-{
-private:
-    struct __two {char __lx; char __lxx;};
-    template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::propagate_on_container_swap* = 0);
-public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
-};
+struct __has_propagate_on_container_swap<_Tp, 
+           typename __void_t<typename _Tp::propagate_on_container_swap>::type>
+               : true_type {};
 
 template <class _Alloc, bool = __has_propagate_on_container_swap<_Alloc>::value>
 struct __propagate_on_container_swap
@@ -1205,16 +1184,13 @@ struct __propagate_on_container_swap<_Alloc, true>
     typedef typename _Alloc::propagate_on_container_swap type;
 };
 
+template <class _Tp, class = void>
+struct __has_is_always_equal : false_type {};
+
 template <class _Tp>
-struct __has_is_always_equal
-{
-private:
-    struct __two {char __lx; char __lxx;};
-    template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::is_always_equal* = 0);
-public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
-};
+struct __has_is_always_equal<_Tp, 
+           typename __void_t<typename _Tp::is_always_equal>::type>
+               : true_type {};
 
 template <class _Alloc, bool = __has_is_always_equal<_Alloc>::value>
 struct __is_always_equal
@@ -1526,7 +1502,7 @@ struct _LIBCPP_TEMPLATE_VIS allocator_traits
         {return __a.allocate(__n);}
     _LIBCPP_INLINE_VISIBILITY
     static pointer allocate(allocator_type& __a, size_type __n, const_void_pointer __hint)
-        {return allocate(__a, __n, __hint,
+        {return __allocate(__a, __n, __hint,
             __has_allocate_hint<allocator_type, size_type, const_void_pointer>());}
 
     _LIBCPP_INLINE_VISIBILITY
@@ -1542,26 +1518,26 @@ struct _LIBCPP_TEMPLATE_VIS allocator_traits
 #else  // _LIBCPP_HAS_NO_VARIADICS
     template <class _Tp>
         _LIBCPP_INLINE_VISIBILITY
-        static void construct(allocator_type& __a, _Tp* __p)
+        static void construct(allocator_type&, _Tp* __p)
             {
                 ::new ((void*)__p) _Tp();
             }
     template <class _Tp, class _A0>
         _LIBCPP_INLINE_VISIBILITY
-        static void construct(allocator_type& __a, _Tp* __p, const _A0& __a0)
+        static void construct(allocator_type&, _Tp* __p, const _A0& __a0)
             {
                 ::new ((void*)__p) _Tp(__a0);
             }
     template <class _Tp, class _A0, class _A1>
         _LIBCPP_INLINE_VISIBILITY
-        static void construct(allocator_type& __a, _Tp* __p, const _A0& __a0,
+        static void construct(allocator_type&, _Tp* __p, const _A0& __a0,
                               const _A1& __a1)
             {
                 ::new ((void*)__p) _Tp(__a0, __a1);
             }
     template <class _Tp, class _A0, class _A1, class _A2>
         _LIBCPP_INLINE_VISIBILITY
-        static void construct(allocator_type& __a, _Tp* __p, const _A0& __a0,
+        static void construct(allocator_type&, _Tp* __p, const _A0& __a0,
                               const _A1& __a1, const _A2& __a2)
             {
                 ::new ((void*)__p) _Tp(__a0, __a1, __a2);
@@ -1580,7 +1556,7 @@ struct _LIBCPP_TEMPLATE_VIS allocator_traits
     _LIBCPP_INLINE_VISIBILITY
     static allocator_type
         select_on_container_copy_construction(const allocator_type& __a)
-            {return select_on_container_copy_construction(
+            {return __select_on_container_copy_construction(
                 __has_select_on_container_copy_construction<const allocator_type>(),
                 __a);}
 
@@ -1679,11 +1655,11 @@ struct _LIBCPP_TEMPLATE_VIS allocator_traits
 private:
 
     _LIBCPP_INLINE_VISIBILITY
-    static pointer allocate(allocator_type& __a, size_type __n,
+    static pointer __allocate(allocator_type& __a, size_type __n,
         const_void_pointer __hint, true_type)
         {return __a.allocate(__n, __hint);}
     _LIBCPP_INLINE_VISIBILITY
-    static pointer allocate(allocator_type& __a, size_type __n,
+    static pointer __allocate(allocator_type& __a, size_type __n,
         const_void_pointer, false_type)
         {return __a.allocate(__n);}
 
@@ -1720,11 +1696,11 @@ private:
 
     _LIBCPP_INLINE_VISIBILITY
     static allocator_type
-        select_on_container_copy_construction(true_type, const allocator_type& __a)
+        __select_on_container_copy_construction(true_type, const allocator_type& __a)
             {return __a.select_on_container_copy_construction();}
     _LIBCPP_INLINE_VISIBILITY
     static allocator_type
-        select_on_container_copy_construction(false_type, const allocator_type& __a)
+        __select_on_container_copy_construction(false_type, const allocator_type& __a)
             {return __a;}
 };
 
@@ -1867,7 +1843,7 @@ public:
         return static_cast<pointer>(_VSTD::__allocate(__n * sizeof(_Tp)));
     }
     _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type) _NOEXCEPT
-        {_VSTD::__libcpp_deallocate((void*)__p);}
+        {_VSTD::__libcpp_deallocate((void*) const_cast<_Tp *>(__p));}
     _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT
         {return size_type(~0) / sizeof(_Tp);}
 #if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
@@ -1883,7 +1859,7 @@ public:
         void
         construct(pointer __p)
         {
-            ::new((void*)__p) _Tp();
+            ::new((void*) const_cast<_Tp *>(__p)) _Tp();
         }
 # if defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
 
@@ -1892,14 +1868,14 @@ public:
         void
         construct(pointer __p, _A0& __a0)
         {
-            ::new((void*)__p) _Tp(__a0);
+            ::new((void*) const_cast<_Tp *>(__p)) _Tp(__a0);
         }
     template <class _A0>
         _LIBCPP_INLINE_VISIBILITY
         void
         construct(pointer __p, const _A0& __a0)
         {
-            ::new((void*)__p) _Tp(__a0);
+            ::new((void*) const_cast<_Tp *>(__p)) _Tp(__a0);
         }
 # endif  // defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
     template <class _A0, class _A1>
@@ -1907,28 +1883,28 @@ public:
         void
         construct(pointer __p, _A0& __a0, _A1& __a1)
         {
-            ::new((void*)__p) _Tp(__a0, __a1);
+            ::new((void*) const_cast<_Tp *>(__p)) _Tp(__a0, __a1);
         }
     template <class _A0, class _A1>
         _LIBCPP_INLINE_VISIBILITY
         void
         construct(pointer __p, const _A0& __a0, _A1& __a1)
         {
-            ::new((void*)__p) _Tp(__a0, __a1);
+            ::new((void*) const_cast<_Tp *>(__p)) _Tp(__a0, __a1);
         }
     template <class _A0, class _A1>
         _LIBCPP_INLINE_VISIBILITY
         void
         construct(pointer __p, _A0& __a0, const _A1& __a1)
         {
-            ::new((void*)__p) _Tp(__a0, __a1);
+            ::new((void*) const_cast<_Tp *>(__p)) _Tp(__a0, __a1);
         }
     template <class _A0, class _A1>
         _LIBCPP_INLINE_VISIBILITY
         void
         construct(pointer __p, const _A0& __a0, const _A1& __a1)
         {
-            ::new((void*)__p) _Tp(__a0, __a1);
+            ::new((void*) const_cast<_Tp *>(__p)) _Tp(__a0, __a1);
         }
 #endif  // !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
     _LIBCPP_INLINE_VISIBILITY void destroy(pointer __p) {__p->~_Tp();}
@@ -1996,6 +1972,7 @@ template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
 void return_temporary_buffer(_Tp* __p) _NOEXCEPT {::operator delete(__p);}
 
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
 template <class _Tp>
 struct auto_ptr_ref
 {
@@ -2052,776 +2029,819 @@ class _LIBCPP_TEMPLATE_VIS auto_ptr<void>
 public:
     typedef void element_type;
 };
+#endif
 
-template <class _T1, class _T2, bool = is_same<typename remove_cv<_T1>::type,
-                                                     typename remove_cv<_T2>::type>::value,
-                                bool = is_empty<_T1>::value
-                                       && !__libcpp_is_final<_T1>::value,
-                                bool = is_empty<_T2>::value
-                                       && !__libcpp_is_final<_T2>::value
-         >
-struct __libcpp_compressed_pair_switch;
+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;
 
-template <class _T1, class _T2, bool IsSame>
-struct __libcpp_compressed_pair_switch<_T1, _T2, IsSame, false, false> {enum {value = 0};};
+#ifndef _LIBCPP_CXX03_LANG
+  constexpr __compressed_pair_elem() : __value_() {}
+
+  template <class _Up, class = typename enable_if<
+      !is_same<__compressed_pair_elem, typename decay<_Up>::type>::value
+  >::type>
+  constexpr explicit
+  __compressed_pair_elem(_Up&& __u)
+      : __value_(_VSTD::forward<_Up>(__u)){};
+
+  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))...) {}
+#else
+  __compressed_pair_elem() : __value_() {}
+  __compressed_pair_elem(_ParamT __p) : __value_(std::forward<_ParamT>(__p)) {}
+#endif
 
-template <class _T1, class _T2, bool IsSame>
-struct __libcpp_compressed_pair_switch<_T1, _T2, IsSame, true, false>  {enum {value = 1};};
+  reference __get() _NOEXCEPT { return __value_; }
+  const_reference __get() const _NOEXCEPT { return __value_; }
 
-template <class _T1, class _T2, bool IsSame>
-struct __libcpp_compressed_pair_switch<_T1, _T2, IsSame, false, true>  {enum {value = 2};};
+private:
+  _Tp __value_;
+};
 
-template <class _T1, class _T2>
-struct __libcpp_compressed_pair_switch<_T1, _T2, false, true, true>    {enum {value = 3};};
+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;
 
-template <class _T1, class _T2>
-struct __libcpp_compressed_pair_switch<_T1, _T2, true, true, true>     {enum {value = 1};};
+#ifndef _LIBCPP_CXX03_LANG
+  constexpr __compressed_pair_elem() = default;
+
+  template <class _Up, class = typename enable_if<
+        !is_same<__compressed_pair_elem, typename decay<_Up>::type>::value
+  >::type>
+  constexpr explicit
+  __compressed_pair_elem(_Up&& __u)
+      : __value_type(_VSTD::forward<_Up>(__u)){};
+
+  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))...) {}
+#else
+  __compressed_pair_elem() : __value_type() {}
+  __compressed_pair_elem(_ParamT __p)
+      : __value_type(std::forward<_ParamT>(__p)) {}
+#endif
 
-template <class _T1, class _T2, unsigned = __libcpp_compressed_pair_switch<_T1, _T2>::value>
-class __libcpp_compressed_pair_imp;
+  reference __get() _NOEXCEPT { return *this; }
+  const_reference __get() const _NOEXCEPT { return *this; }
+};
+
+// Tag used to construct the second element of the compressed pair.
+struct __second_tag {};
 
 template <class _T1, class _T2>
-class __libcpp_compressed_pair_imp<_T1, _T2, 0>
-{
-private:
-    _T1 __first_;
-    _T2 __second_;
+class __compressed_pair : private __compressed_pair_elem<_T1, 0>,
+                          private __compressed_pair_elem<_T2, 1> {
+  typedef __compressed_pair_elem<_T1, 0> _Base1;
+  typedef __compressed_pair_elem<_T2, 1> _Base2;
+
+  // 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 instantated when T1 and T2 are the same type; "
+    "The current implementation is NOT ABI-compatible with the previous "
+    "implementation for this configuration");
+
 public:
-    typedef _T1 _T1_param;
-    typedef _T2 _T2_param;
+#ifndef _LIBCPP_CXX03_LANG
+  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
+  constexpr __compressed_pair() {}
+
+  template <class _Tp, typename enable_if<!is_same<typename decay<_Tp>::type,
+                                                   __compressed_pair>::value,
+                                          bool>::type = true>
+  _LIBCPP_INLINE_VISIBILITY constexpr explicit
+  __compressed_pair(_Tp&& __t)
+      : _Base1(std::forward<_Tp>(__t)), _Base2() {}
+
+  template <class _Tp>
+  _LIBCPP_INLINE_VISIBILITY constexpr
+  __compressed_pair(__second_tag, _Tp&& __t)
+      : _Base1(), _Base2(std::forward<_Tp>(__t)) {}
+
+  template <class _U1, class _U2>
+  _LIBCPP_INLINE_VISIBILITY constexpr
+  __compressed_pair(_U1&& __t1, _U2&& __t2)
+      : _Base1(std::forward<_U1>(__t1)), _Base2(std::forward<_U2>(__t2)) {}
+
+  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()) {}
 
-    typedef typename remove_reference<_T1>::type& _T1_reference;
-    typedef typename remove_reference<_T2>::type& _T2_reference;
+#else
+  _LIBCPP_INLINE_VISIBILITY
+  __compressed_pair() {}
 
-    typedef const typename remove_reference<_T1>::type& _T1_const_reference;
-    typedef const typename remove_reference<_T2>::type& _T2_const_reference;
+  _LIBCPP_INLINE_VISIBILITY explicit
+  __compressed_pair(_T1 __t1) : _Base1(_VSTD::forward<_T1>(__t1)) {}
 
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp() : __first_(), __second_() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T1_param __t1)
-        : __first_(_VSTD::forward<_T1_param>(__t1)), __second_() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2)
-        : __first_(), __second_(_VSTD::forward<_T2_param>(__t2)) {}
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
-        : __first_(_VSTD::forward<_T1_param>(__t1)), __second_(_VSTD::forward<_T2_param>(__t2)) {}
+  _LIBCPP_INLINE_VISIBILITY
+  __compressed_pair(__second_tag, _T2 __t2)
+      : _Base1(), _Base2(_VSTD::forward<_T2>(__t2)) {}
 
-#ifndef _LIBCPP_HAS_NO_VARIADICS
+  _LIBCPP_INLINE_VISIBILITY
+  __compressed_pair(_T1 __t1, _T2 __t2)
+      : _Base1(_VSTD::forward<_T1>(__t1)), _Base2(_VSTD::forward<_T2>(__t2)) {}
+#endif
 
-    template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
-        _LIBCPP_INLINE_VISIBILITY
-        __libcpp_compressed_pair_imp(piecewise_construct_t,
-                                     tuple<_Args1...> __first_args,
-                                     tuple<_Args2...> __second_args,
-                                     __tuple_indices<_I1...>,
-                                     __tuple_indices<_I2...>)
-            : __first_(_VSTD::forward<_Args1>(_VSTD::get<_I1>(__first_args))...),
-              __second_(_VSTD::forward<_Args2>(_VSTD::get<_I2>(__second_args))...)
-            {}
+  _LIBCPP_INLINE_VISIBILITY
+  typename _Base1::reference first() _NOEXCEPT {
+    return static_cast<_Base1&>(*this).__get();
+  }
 
-#endif  // _LIBCPP_HAS_NO_VARIADICS
+  _LIBCPP_INLINE_VISIBILITY
+  typename _Base1::const_reference first() const _NOEXCEPT {
+    return static_cast<_Base1 const&>(*this).__get();
+  }
 
-    _LIBCPP_INLINE_VISIBILITY _T1_reference       first() _NOEXCEPT       {return __first_;}
-    _LIBCPP_INLINE_VISIBILITY _T1_const_reference first() const _NOEXCEPT {return __first_;}
+  _LIBCPP_INLINE_VISIBILITY
+  typename _Base2::reference second() _NOEXCEPT {
+    return static_cast<_Base2&>(*this).__get();
+  }
 
-    _LIBCPP_INLINE_VISIBILITY _T2_reference       second() _NOEXCEPT       {return __second_;}
-    _LIBCPP_INLINE_VISIBILITY _T2_const_reference second() const _NOEXCEPT {return __second_;}
+  _LIBCPP_INLINE_VISIBILITY
+  typename _Base2::const_reference second() const _NOEXCEPT {
+    return static_cast<_Base2 const&>(*this).__get();
+  }
 
-    _LIBCPP_INLINE_VISIBILITY void swap(__libcpp_compressed_pair_imp& __x)
-        _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
-                   __is_nothrow_swappable<_T2>::value)
-    {
-        using _VSTD::swap;
-        swap(__first_, __x.__first_);
-        swap(__second_, __x.__second_);
-    }
+  _LIBCPP_INLINE_VISIBILITY
+  void swap(__compressed_pair& __x)
+    _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
+               __is_nothrow_swappable<_T2>::value)
+  {
+    using std::swap;
+    swap(first(), __x.first());
+    swap(second(), __x.second());
+  }
 };
 
 template <class _T1, class _T2>
-class __libcpp_compressed_pair_imp<_T1, _T2, 1>
-    : private _T1
-{
-private:
-    _T2 __second_;
-public:
-    typedef _T1 _T1_param;
-    typedef _T2 _T2_param;
-
-    typedef _T1&                                        _T1_reference;
-    typedef typename remove_reference<_T2>::type& _T2_reference;
-
-    typedef const _T1&                                        _T1_const_reference;
-    typedef const typename remove_reference<_T2>::type& _T2_const_reference;
-
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp() : __second_() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T1_param __t1)
-        : _T1(_VSTD::forward<_T1_param>(__t1)), __second_() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2)
-        : __second_(_VSTD::forward<_T2_param>(__t2)) {}
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
-        : _T1(_VSTD::forward<_T1_param>(__t1)), __second_(_VSTD::forward<_T2_param>(__t2)) {}
-
-#ifndef _LIBCPP_HAS_NO_VARIADICS
-
-    template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
-        _LIBCPP_INLINE_VISIBILITY
-        __libcpp_compressed_pair_imp(piecewise_construct_t,
-                                     tuple<_Args1...> __first_args,
-                                     tuple<_Args2...> __second_args,
-                                     __tuple_indices<_I1...>,
-                                     __tuple_indices<_I2...>)
-            : _T1(_VSTD::forward<_Args1>(_VSTD::get<_I1>(__first_args))...),
-              __second_(_VSTD::forward<_Args2>(_VSTD::get<_I2>(__second_args))...)
-            {}
-
-#endif  // _LIBCPP_HAS_NO_VARIADICS
-
-    _LIBCPP_INLINE_VISIBILITY _T1_reference       first() _NOEXCEPT       {return *this;}
-    _LIBCPP_INLINE_VISIBILITY _T1_const_reference first() const _NOEXCEPT {return *this;}
+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_INLINE_VISIBILITY _T2_reference       second() _NOEXCEPT       {return __second_;}
-    _LIBCPP_INLINE_VISIBILITY _T2_const_reference second() const _NOEXCEPT {return __second_;}
+// default_delete
 
-    _LIBCPP_INLINE_VISIBILITY void swap(__libcpp_compressed_pair_imp& __x)
-        _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
-                   __is_nothrow_swappable<_T2>::value)
-    {
-        using _VSTD::swap;
-        swap(__second_, __x.__second_);
-    }
+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 _T1, class _T2>
-class __libcpp_compressed_pair_imp<_T1, _T2, 2>
-    : private _T2
-{
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS default_delete<_Tp[]> {
 private:
-    _T1 __first_;
-public:
-    typedef _T1 _T1_param;
-    typedef _T2 _T2_param;
-
-    typedef typename remove_reference<_T1>::type& _T1_reference;
-    typedef _T2&                                        _T2_reference;
+  template <class _Up>
+  struct _EnableIfConvertible
+      : enable_if<is_convertible<_Up(*)[], _Tp(*)[]>::value> {};
 
-    typedef const typename remove_reference<_T1>::type& _T1_const_reference;
-    typedef const _T2&                                        _T2_const_reference;
+public:
+#ifndef _LIBCPP_CXX03_LANG
+  _LIBCPP_INLINE_VISIBILITY constexpr default_delete() noexcept = default;
+#else
+  _LIBCPP_INLINE_VISIBILITY default_delete() {}
+#endif
 
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp() : __first_() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T1_param __t1)
-        : __first_(_VSTD::forward<_T1_param>(__t1)) {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2)
-        : _T2(_VSTD::forward<_T2_param>(__t2)), __first_() {}
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
-        _NOEXCEPT_(is_nothrow_move_constructible<_T1>::value &&
-                   is_nothrow_move_constructible<_T2>::value)
-        : _T2(_VSTD::forward<_T2_param>(__t2)), __first_(_VSTD::forward<_T1_param>(__t1)) {}
+  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;
+  }
+};
 
-#ifndef _LIBCPP_HAS_NO_VARIADICS
 
-    template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
-        _LIBCPP_INLINE_VISIBILITY
-        __libcpp_compressed_pair_imp(piecewise_construct_t,
-                                     tuple<_Args1...> __first_args,
-                                     tuple<_Args2...> __second_args,
-                                     __tuple_indices<_I1...>,
-                                     __tuple_indices<_I2...>)
-            : _T2(_VSTD::forward<_Args2>(_VSTD::get<_I2>(__second_args))...),
-              __first_(_VSTD::forward<_Args1>(_VSTD::get<_I1>(__first_args))...)
-              
-            {}
 
-#endif  // _LIBCPP_HAS_NO_VARIADICS
-
-    _LIBCPP_INLINE_VISIBILITY _T1_reference       first() _NOEXCEPT       {return __first_;}
-    _LIBCPP_INLINE_VISIBILITY _T1_const_reference first() const _NOEXCEPT {return __first_;}
+#ifndef _LIBCPP_CXX03_LANG
+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;
+};
 
-    _LIBCPP_INLINE_VISIBILITY _T2_reference       second() _NOEXCEPT       {return *this;}
-    _LIBCPP_INLINE_VISIBILITY _T2_const_reference second() const _NOEXCEPT {return *this;}
+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;
+};
 
-    _LIBCPP_INLINE_VISIBILITY void swap(__libcpp_compressed_pair_imp& __x)
-        _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
-                   __is_nothrow_swappable<_T2>::value)
-    {
-        using _VSTD::swap;
-        swap(__first_, __x.__first_);
-    }
+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;
 };
+#endif // !defined(_LIBCPP_CXX03_LANG)
 
-template <class _T1, class _T2>
-class __libcpp_compressed_pair_imp<_T1, _T2, 3>
-    : private _T1,
-      private _T2
-{
+template <class _Tp, class _Dp = default_delete<_Tp> >
+class _LIBCPP_TEMPLATE_VIS unique_ptr {
 public:
-    typedef _T1 _T1_param;
-    typedef _T2 _T2_param;
-
-    typedef _T1& _T1_reference;
-    typedef _T2& _T2_reference;
-
-    typedef const _T1& _T1_const_reference;
-    typedef const _T2& _T2_const_reference;
+  typedef _Tp element_type;
+  typedef _Dp deleter_type;
+  typedef typename __pointer_type<_Tp, deleter_type>::type pointer;
 
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T1_param __t1)
-        : _T1(_VSTD::forward<_T1_param>(__t1)) {}
-    _LIBCPP_INLINE_VISIBILITY explicit __libcpp_compressed_pair_imp(_T2_param __t2)
-        : _T2(_VSTD::forward<_T2_param>(__t2)) {}
-    _LIBCPP_INLINE_VISIBILITY __libcpp_compressed_pair_imp(_T1_param __t1, _T2_param __t2)
-        : _T1(_VSTD::forward<_T1_param>(__t1)), _T2(_VSTD::forward<_T2_param>(__t2)) {}
-
-#ifndef _LIBCPP_HAS_NO_VARIADICS
-
-    template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
-        _LIBCPP_INLINE_VISIBILITY
-        __libcpp_compressed_pair_imp(piecewise_construct_t,
-                                     tuple<_Args1...> __first_args,
-                                     tuple<_Args2...> __second_args,
-                                     __tuple_indices<_I1...>,
-                                     __tuple_indices<_I2...>)
-            : _T1(_VSTD::forward<_Args1>(_VSTD::get<_I1>(__first_args))...),
-              _T2(_VSTD::forward<_Args2>(_VSTD::get<_I2>(__second_args))...)
-            {}
-
-#endif  // _LIBCPP_HAS_NO_VARIADICS
+  static_assert(!is_rvalue_reference<deleter_type>::value,
+                "the specified deleter type cannot be an rvalue reference");
 
-    _LIBCPP_INLINE_VISIBILITY _T1_reference       first() _NOEXCEPT       {return *this;}
-    _LIBCPP_INLINE_VISIBILITY _T1_const_reference first() const _NOEXCEPT {return *this;}
+private:
+  __compressed_pair<pointer, deleter_type> __ptr_;
 
-    _LIBCPP_INLINE_VISIBILITY _T2_reference       second() _NOEXCEPT       {return *this;}
-    _LIBCPP_INLINE_VISIBILITY _T2_const_reference second() const _NOEXCEPT {return *this;}
+  struct __nat { int __for_bool_; };
 
-    _LIBCPP_INLINE_VISIBILITY void swap(__libcpp_compressed_pair_imp&)
-        _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
-                   __is_nothrow_swappable<_T2>::value)
-    {
-    }
-};
+#ifndef _LIBCPP_CXX03_LANG
+  typedef __unique_ptr_deleter_sfinae<_Dp> _DeleterSFINAE;
+
+  template <bool _Dummy>
+  using _LValRefType =
+      typename __dependent_type<_DeleterSFINAE, _Dummy>::__lval_ref_type;
+
+  template <bool _Dummy>
+  using _GoodRValRefType =
+      typename __dependent_type<_DeleterSFINAE, _Dummy>::__good_rval_ref_type;
+
+  template <bool _Dummy>
+  using _BadRValRefType =
+      typename __dependent_type<_DeleterSFINAE, _Dummy>::__bad_rval_ref_type;
+
+  template <bool _Dummy, class _Deleter = typename __dependent_type<
+                             __identity<deleter_type>, _Dummy>::type>
+  using _EnableIfDeleterDefaultConstructible =
+      typename enable_if<is_default_constructible<_Deleter>::value &&
+                         !is_pointer<_Deleter>::value>::type;
+
+  template <class _ArgType>
+  using _EnableIfDeleterConstructible =
+      typename enable_if<is_constructible<deleter_type, _ArgType>::value>::type;
+
+  template <class _UPtr, class _Up>
+  using _EnableIfMoveConvertible = typename enable_if<
+      is_convertible<typename _UPtr::pointer, pointer>::value &&
+      !is_array<_Up>::value
+  >::type;
+
+  template <class _UDel>
+  using _EnableIfDeleterConvertible = 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;
 
-template <class _T1, class _T2>
-class __compressed_pair
-    : private __libcpp_compressed_pair_imp<_T1, _T2>
-{
-    typedef __libcpp_compressed_pair_imp<_T1, _T2> base;
 public:
-    typedef typename base::_T1_param _T1_param;
-    typedef typename base::_T2_param _T2_param;
-
-    typedef typename base::_T1_reference _T1_reference;
-    typedef typename base::_T2_reference _T2_reference;
-
-    typedef typename base::_T1_const_reference _T1_const_reference;
-    typedef typename base::_T2_const_reference _T2_const_reference;
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterDefaultConstructible<_Dummy>>
+  _LIBCPP_INLINE_VISIBILITY
+  constexpr unique_ptr() noexcept : __ptr_(pointer()) {}
+
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterDefaultConstructible<_Dummy>>
+  _LIBCPP_INLINE_VISIBILITY
+  constexpr unique_ptr(nullptr_t) noexcept : __ptr_(pointer()) {}
+
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterDefaultConstructible<_Dummy>>
+  _LIBCPP_INLINE_VISIBILITY
+  explicit unique_ptr(pointer __p) noexcept : __ptr_(__p) {}
+
+  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");
+  }
 
-    _LIBCPP_INLINE_VISIBILITY __compressed_pair() {}
-    _LIBCPP_INLINE_VISIBILITY explicit __compressed_pair(_T1_param __t1)
-        : base(_VSTD::forward<_T1_param>(__t1)) {}
-    _LIBCPP_INLINE_VISIBILITY explicit __compressed_pair(_T2_param __t2)
-        : base(_VSTD::forward<_T2_param>(__t2)) {}
-    _LIBCPP_INLINE_VISIBILITY __compressed_pair(_T1_param __t1, _T2_param __t2)
-        : base(_VSTD::forward<_T1_param>(__t1), _VSTD::forward<_T2_param>(__t2)) {}
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterConstructible<_BadRValRefType<_Dummy>>>
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(pointer __p, _BadRValRefType<_Dummy> __d) = delete;
 
-#ifndef _LIBCPP_HAS_NO_VARIADICS
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(unique_ptr&& __u) noexcept
+      : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {
+  }
 
-    template <class... _Args1, class... _Args2>
-        _LIBCPP_INLINE_VISIBILITY
-        __compressed_pair(piecewise_construct_t __pc, tuple<_Args1...> __first_args,
-                                                      tuple<_Args2...> __second_args)
-            : base(__pc, _VSTD::move(__first_args), _VSTD::move(__second_args),
-                   typename __make_tuple_indices<sizeof...(_Args1)>::type(),
-                   typename __make_tuple_indices<sizeof...(_Args2) >::type())
-            {}
+  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()) {}
+#endif
 
-#endif  // _LIBCPP_HAS_NO_VARIADICS
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr& operator=(unique_ptr&& __u) _NOEXCEPT {
+    reset(__u.release());
+    __ptr_.second() = _VSTD::forward<deleter_type>(__u.get_deleter());
+    return *this;
+  }
 
-    _LIBCPP_INLINE_VISIBILITY _T1_reference       first() _NOEXCEPT       {return base::first();}
-    _LIBCPP_INLINE_VISIBILITY _T1_const_reference first() const _NOEXCEPT {return base::first();}
+  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;
+  }
 
-    _LIBCPP_INLINE_VISIBILITY _T2_reference       second() _NOEXCEPT       {return base::second();}
-    _LIBCPP_INLINE_VISIBILITY _T2_const_reference second() const _NOEXCEPT {return base::second();}
+#else  // _LIBCPP_CXX03_LANG
+private:
+  unique_ptr(unique_ptr&);
+  template <class _Up, class _Ep> unique_ptr(unique_ptr<_Up, _Ep>&);
 
-    _LIBCPP_INLINE_VISIBILITY void swap(__compressed_pair& __x)
-        _NOEXCEPT_(__is_nothrow_swappable<_T1>::value &&
-                   __is_nothrow_swappable<_T2>::value)
-        {base::swap(__x);}
-};
+  unique_ptr& operator=(unique_ptr&);
+  template <class _Up, class _Ep> unique_ptr& operator=(unique_ptr<_Up, _Ep>&);
 
-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);}
-
-// __same_or_less_cv_qualified
-
-template <class _Ptr1, class _Ptr2,
-          bool = is_same<typename remove_cv<typename pointer_traits<_Ptr1>::element_type>::type,
-                         typename remove_cv<typename pointer_traits<_Ptr2>::element_type>::type
-                        >::value
-         >
-struct __same_or_less_cv_qualified_imp
-    : is_convertible<_Ptr1, _Ptr2> {};
-
-template <class _Ptr1, class _Ptr2>
-struct __same_or_less_cv_qualified_imp<_Ptr1, _Ptr2, false>
-    : false_type {};
-
-template <class _Ptr1, class _Ptr2, bool = is_pointer<_Ptr1>::value ||
-                                           is_same<_Ptr1, _Ptr2>::value ||
-                                           __has_element_type<_Ptr1>::value>
-struct __same_or_less_cv_qualified
-    : __same_or_less_cv_qualified_imp<_Ptr1, _Ptr2> {};
-
-template <class _Ptr1, class _Ptr2>
-struct __same_or_less_cv_qualified<_Ptr1, _Ptr2, false>
-    : false_type {};
+public:
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr() : __ptr_(pointer())
+  {
+    static_assert(!is_pointer<deleter_type>::value,
+                  "unique_ptr constructed with null function pointer deleter");
+    static_assert(is_default_constructible<deleter_type>::value,
+                  "unique_ptr::deleter_type is not default constructible");
+  }
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(nullptr_t) : __ptr_(pointer())
+  {
+    static_assert(!is_pointer<deleter_type>::value,
+                  "unique_ptr constructed with null function pointer deleter");
+  }
+  _LIBCPP_INLINE_VISIBILITY
+  explicit unique_ptr(pointer __p)
+      : __ptr_(_VSTD::move(__p)) {
+    static_assert(!is_pointer<deleter_type>::value,
+                  "unique_ptr constructed with null function pointer deleter");
+  }
 
-// default_delete
+  _LIBCPP_INLINE_VISIBILITY
+  operator __rv<unique_ptr>() {
+    return __rv<unique_ptr>(*this);
+  }
 
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS default_delete
-{
-#ifndef _LIBCPP_CXX03_LANG
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR default_delete() _NOEXCEPT = default;
-#else
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR default_delete() _NOEXCEPT {}
-#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;
-        }
-};
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(__rv<unique_ptr> __u)
+      : __ptr_(__u->release(),
+               _VSTD::forward<deleter_type>(__u->get_deleter())) {}
+
+  template <class _Up, class _Ep>
+  _LIBCPP_INLINE_VISIBILITY
+  typename enable_if<
+      !is_array<_Up>::value &&
+          is_convertible<typename unique_ptr<_Up, _Ep>::pointer,
+                         pointer>::value &&
+          is_assignable<deleter_type&, _Ep&>::value,
+      unique_ptr&>::type
+  operator=(unique_ptr<_Up, _Ep> __u) {
+    reset(__u.release());
+    __ptr_.second() = _VSTD::forward<_Ep>(__u.get_deleter());
+    return *this;
+  }
 
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS default_delete<_Tp[]>
-{
-public:
-#ifndef _LIBCPP_CXX03_LANG
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR default_delete() _NOEXCEPT = default;
-#else
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR default_delete() _NOEXCEPT {}
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(pointer __p, deleter_type __d)
+      : __ptr_(_VSTD::move(__p), _VSTD::move(__d)) {}
+#endif // _LIBCPP_CXX03_LANG
+
+#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
-    template <class _Up>
-        _LIBCPP_INLINE_VISIBILITY default_delete(const default_delete<_Up[]>&,
-             typename enable_if<__same_or_less_cv_qualified<_Up*, _Tp*>::value>::type* = 0) _NOEXCEPT {}
-    template <class _Up>
-        _LIBCPP_INLINE_VISIBILITY
-        void operator() (_Up* __ptr,
-                         typename enable_if<__same_or_less_cv_qualified<_Up*, _Tp*>::value>::type* = 0) 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 _Tp, class _Dp = default_delete<_Tp> >
-class _LIBCPP_TEMPLATE_VIS unique_ptr
-{
-public:
-    typedef _Tp element_type;
-    typedef _Dp deleter_type;
-    typedef typename __pointer_type<_Tp, deleter_type>::type pointer;
-private:
-    __compressed_pair<pointer, deleter_type> __ptr_;
+  _LIBCPP_INLINE_VISIBILITY
+  ~unique_ptr() { reset(); }
 
-#ifdef _LIBCPP_HAS_NO_RVALUE_REFERENCES
-    unique_ptr(unique_ptr&);
-    template <class _Up, class _Ep>
-        unique_ptr(unique_ptr<_Up, _Ep>&);
-    unique_ptr& operator=(unique_ptr&);
-    template <class _Up, class _Ep>
-        unique_ptr& operator=(unique_ptr<_Up, _Ep>&);
-#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
-
-    struct __nat {int __for_bool_;};
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr& operator=(nullptr_t) _NOEXCEPT {
+    reset();
+    return *this;
+  }
 
-    typedef       typename remove_reference<deleter_type>::type& _Dp_reference;
-    typedef const typename remove_reference<deleter_type>::type& _Dp_const_reference;
-public:
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR unique_ptr() _NOEXCEPT
-        : __ptr_(pointer())
-        {
-            static_assert(!is_pointer<deleter_type>::value,
-                "unique_ptr constructed with null function pointer deleter");
-        }
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR unique_ptr(nullptr_t) _NOEXCEPT
-        : __ptr_(pointer())
-        {
-            static_assert(!is_pointer<deleter_type>::value,
-                "unique_ptr constructed with null function pointer deleter");
-        }
-    _LIBCPP_INLINE_VISIBILITY explicit unique_ptr(pointer __p) _NOEXCEPT
-        : __ptr_(_VSTD::move(__p))
-        {
-            static_assert(!is_pointer<deleter_type>::value,
-                "unique_ptr constructed with null function pointer deleter");
-        }
+  _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;
+  }
 
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(pointer __p, typename conditional<
-                                        is_reference<deleter_type>::value,
-                                        deleter_type,
-                                        typename add_lvalue_reference<const deleter_type>::type>::type __d)
-             _NOEXCEPT
-        : __ptr_(__p, __d) {}
+  _LIBCPP_INLINE_VISIBILITY
+  pointer release() _NOEXCEPT {
+    pointer __t = __ptr_.first();
+    __ptr_.first() = pointer();
+    return __t;
+  }
 
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(pointer __p, typename remove_reference<deleter_type>::type&& __d)
-             _NOEXCEPT
-        : __ptr_(__p, _VSTD::move(__d))
-        {
-            static_assert(!is_reference<deleter_type>::value, "rvalue deleter bound to reference");
-        }
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(unique_ptr&& __u) _NOEXCEPT
-        : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {}
-    template <class _Up, class _Ep>
-        _LIBCPP_INLINE_VISIBILITY
-        unique_ptr(unique_ptr<_Up, _Ep>&& __u,
-                   typename enable_if
-                      <
-                        !is_array<_Up>::value &&
-                         is_convertible<typename unique_ptr<_Up, _Ep>::pointer, pointer>::value &&
-                         is_convertible<_Ep, deleter_type>::value &&
-                         (
-                            !is_reference<deleter_type>::value ||
-                            is_same<deleter_type, _Ep>::value
-                         ),
-                         __nat
-                      >::type = __nat()) _NOEXCEPT
-            : __ptr_(__u.release(), _VSTD::forward<_Ep>(__u.get_deleter())) {}
+  _LIBCPP_INLINE_VISIBILITY
+  void reset(pointer __p = pointer()) _NOEXCEPT {
+    pointer __tmp = __ptr_.first();
+    __ptr_.first() = __p;
+    if (__tmp)
+      __ptr_.second()(__tmp);
+  }
 
-    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())
-            {
-            }
+  _LIBCPP_INLINE_VISIBILITY
+  void swap(unique_ptr& __u) _NOEXCEPT {
+    __ptr_.swap(__u.__ptr_);
+  }
+};
 
-        _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>
-            _LIBCPP_INLINE_VISIBILITY
-            typename enable_if
-            <
-                !is_array<_Up>::value &&
-                is_convertible<typename unique_ptr<_Up, _Ep>::pointer, pointer>::value &&
-                is_assignable<deleter_type&, _Ep&&>::value,
-                unique_ptr&
-            >::type
-            operator=(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT
-            {
-                reset(__u.release());
-                __ptr_.second() = _VSTD::forward<_Ep>(__u.get_deleter());
-                return *this;
-            }
-#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+template <class _Tp, class _Dp>
+class _LIBCPP_TEMPLATE_VIS unique_ptr<_Tp[], _Dp> {
+public:
+  typedef _Tp element_type;
+  typedef _Dp deleter_type;
+  typedef typename __pointer_type<_Tp, deleter_type>::type pointer;
 
-    _LIBCPP_INLINE_VISIBILITY operator __rv<unique_ptr>()
-    {
-        return __rv<unique_ptr>(*this);
-    }
+private:
+  __compressed_pair<pointer, deleter_type> __ptr_;
 
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(__rv<unique_ptr> __u)
-        : __ptr_(__u->release(), _VSTD::forward<deleter_type>(__u->get_deleter())) {}
+  template <class _From>
+  struct _CheckArrayPointerConversion : is_same<_From, pointer> {};
 
-    template <class _Up, class _Ep>
-    _LIBCPP_INLINE_VISIBILITY
-    typename enable_if<
-        !is_array<_Up>::value &&
-        is_convertible<typename unique_ptr<_Up, _Ep>::pointer, pointer>::value &&
-        is_assignable<deleter_type&, _Ep&>::value,
-        unique_ptr&
-    >::type
-    operator=(unique_ptr<_Up, _Ep> __u)
-    {
-        reset(__u.release());
-        __ptr_.second() = _VSTD::forward<_Ep>(__u.get_deleter());
-        return *this;
-    }
+  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)
+      >
+  {};
 
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(pointer __p, deleter_type __d)
-        : __ptr_(_VSTD::move(__p), _VSTD::move(__d)) {}
+#ifndef _LIBCPP_CXX03_LANG
+  typedef __unique_ptr_deleter_sfinae<_Dp> _DeleterSFINAE;
+
+  template <bool _Dummy>
+  using _LValRefType =
+      typename __dependent_type<_DeleterSFINAE, _Dummy>::__lval_ref_type;
+
+  template <bool _Dummy>
+  using _GoodRValRefType =
+      typename __dependent_type<_DeleterSFINAE, _Dummy>::__good_rval_ref_type;
+
+  template <bool _Dummy>
+  using _BadRValRefType =
+      typename __dependent_type<_DeleterSFINAE, _Dummy>::__bad_rval_ref_type;
+
+  template <bool _Dummy, class _Deleter = typename __dependent_type<
+                             __identity<deleter_type>, _Dummy>::type>
+  using _EnableIfDeleterDefaultConstructible =
+      typename enable_if<is_default_constructible<_Deleter>::value &&
+                         !is_pointer<_Deleter>::value>::type;
+
+  template <class _ArgType>
+  using _EnableIfDeleterConstructible =
+      typename enable_if<is_constructible<deleter_type, _ArgType>::value>::type;
+
+  template <class _Pp>
+  using _EnableIfPointerConvertible = typename enable_if<
+      _CheckArrayPointerConversion<_Pp>::value
+  >::type;
+
+  template <class _UPtr, class _Up,
+        class _ElemT = typename _UPtr::element_type>
+  using _EnableIfMoveConvertible = 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 = 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;
 
-    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;}
+public:
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterDefaultConstructible<_Dummy>>
+  _LIBCPP_INLINE_VISIBILITY
+  constexpr unique_ptr() noexcept : __ptr_(pointer()) {}
+
+  template <bool _Dummy = true,
+            class = _EnableIfDeleterDefaultConstructible<_Dummy>>
+  _LIBCPP_INLINE_VISIBILITY
+  constexpr unique_ptr(nullptr_t) noexcept : __ptr_(pointer()) {}
+
+  template <class _Pp, bool _Dummy = true,
+            class = _EnableIfDeleterDefaultConstructible<_Dummy>,
+            class = _EnableIfPointerConvertible<_Pp>>
+  _LIBCPP_INLINE_VISIBILITY
+  explicit unique_ptr(_Pp __p) noexcept
+      : __ptr_(__p) {}
+
+  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");
+  }
 
-#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
-    _LIBCPP_INLINE_VISIBILITY ~unique_ptr() {reset();}
+  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");
+  }
 
-    _LIBCPP_INLINE_VISIBILITY unique_ptr& operator=(nullptr_t) _NOEXCEPT
-    {
-        reset();
-        return *this;
-    }
+  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 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       _Dp_reference get_deleter() _NOEXCEPT
-        {return __ptr_.second();}
-    _LIBCPP_INLINE_VISIBILITY _Dp_const_reference get_deleter() const _NOEXCEPT
-        {return __ptr_.second();}
-    _LIBCPP_INLINE_VISIBILITY
-        _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT
-        {return __ptr_.first() != nullptr;}
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(unique_ptr&& __u) noexcept
+      : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {
+  }
 
-    _LIBCPP_INLINE_VISIBILITY pointer release() _NOEXCEPT
-    {
-        pointer __t = __ptr_.first();
-        __ptr_.first() = pointer();
-        return __t;
-    }
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr& operator=(unique_ptr&& __u) noexcept {
+    reset(__u.release());
+    __ptr_.second() = _VSTD::forward<deleter_type>(__u.get_deleter());
+    return *this;
+  }
 
-    _LIBCPP_INLINE_VISIBILITY void reset(pointer __p = pointer()) _NOEXCEPT
-    {
-        pointer __tmp = __ptr_.first();
-        __ptr_.first() = __p;
-        if (__tmp)
-            __ptr_.second()(__tmp);
-    }
+  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())) {
+  }
 
-    _LIBCPP_INLINE_VISIBILITY void swap(unique_ptr& __u) _NOEXCEPT
-        {__ptr_.swap(__u.__ptr_);}
-};
+  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;
+  }
 
-template <class _Tp, class _Dp>
-class _LIBCPP_TEMPLATE_VIS unique_ptr<_Tp[], _Dp>
-{
-public:
-    typedef _Tp element_type;
-    typedef _Dp deleter_type;
-    typedef typename __pointer_type<_Tp, deleter_type>::type pointer;
+#else // _LIBCPP_CXX03_LANG
 private:
-    __compressed_pair<pointer, deleter_type> __ptr_;
+  template <class _Up> explicit unique_ptr(_Up);
 
-#ifdef _LIBCPP_HAS_NO_RVALUE_REFERENCES
-    unique_ptr(unique_ptr&);
-    template <class _Up>
-        unique_ptr(unique_ptr<_Up>&);
-    unique_ptr& operator=(unique_ptr&);
-    template <class _Up>
-        unique_ptr& operator=(unique_ptr<_Up>&);
-#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+  unique_ptr(unique_ptr&);
+  template <class _Up> unique_ptr(unique_ptr<_Up>&);
 
-    struct __nat {int __for_bool_;};
+  unique_ptr& operator=(unique_ptr&);
+  template <class _Up> unique_ptr& operator=(unique_ptr<_Up>&);
 
-    typedef       typename remove_reference<deleter_type>::type& _Dp_reference;
-    typedef const typename remove_reference<deleter_type>::type& _Dp_const_reference;
+  template <class _Up>
+  unique_ptr(_Up __u,
+             typename conditional<
+                 is_reference<deleter_type>::value, deleter_type,
+                 typename add_lvalue_reference<const deleter_type>::type>::type,
+             typename enable_if<is_convertible<_Up, pointer>::value,
+                                __nat>::type = __nat());
 public:
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR unique_ptr() _NOEXCEPT
-        : __ptr_(pointer())
-        {
-            static_assert(!is_pointer<deleter_type>::value,
-                "unique_ptr constructed with null function pointer deleter");
-        }
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR unique_ptr(nullptr_t) _NOEXCEPT
-        : __ptr_(pointer())
-        {
-            static_assert(!is_pointer<deleter_type>::value,
-                "unique_ptr constructed with null function pointer deleter");
-        }
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
-    template <class _Pp>
-    _LIBCPP_INLINE_VISIBILITY explicit unique_ptr(_Pp __p,
-            typename enable_if<__same_or_less_cv_qualified<_Pp, pointer>::value, __nat>::type = __nat()) _NOEXCEPT
-        : __ptr_(__p)
-        {
-            static_assert(!is_pointer<deleter_type>::value,
-                "unique_ptr constructed with null function pointer deleter");
-        }
-
-    template <class _Pp>
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(_Pp __p, typename conditional<
-                                       is_reference<deleter_type>::value,
-                                       deleter_type,
-                                       typename add_lvalue_reference<const deleter_type>::type>::type __d,
-                                       typename enable_if<__same_or_less_cv_qualified<_Pp, pointer>::value, __nat>::type = __nat())
-             _NOEXCEPT
-        : __ptr_(__p, __d) {}
-
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(nullptr_t, typename conditional<
-                                       is_reference<deleter_type>::value,
-                                       deleter_type,
-                                       typename add_lvalue_reference<const deleter_type>::type>::type __d)
-             _NOEXCEPT
-        : __ptr_(pointer(), __d) {}
-
-    template <class _Pp>
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(_Pp __p,
-                                         typename remove_reference<deleter_type>::type&& __d,
-                                         typename enable_if<__same_or_less_cv_qualified<_Pp, pointer>::value, __nat>::type = __nat())
-             _NOEXCEPT
-        : __ptr_(__p, _VSTD::move(__d))
-        {
-            static_assert(!is_reference<deleter_type>::value, "rvalue deleter bound to reference");
-        }
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr() : __ptr_(pointer()) {
+    static_assert(!is_pointer<deleter_type>::value,
+                  "unique_ptr constructed with null function pointer deleter");
+  }
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(nullptr_t) : __ptr_(pointer()) {
+    static_assert(!is_pointer<deleter_type>::value,
+                  "unique_ptr constructed with null function pointer deleter");
+  }
 
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(nullptr_t, typename remove_reference<deleter_type>::type&& __d)
-             _NOEXCEPT
-        : __ptr_(pointer(), _VSTD::move(__d))
-        {
-            static_assert(!is_reference<deleter_type>::value, "rvalue deleter bound to reference");
-        }
+  _LIBCPP_INLINE_VISIBILITY
+  explicit unique_ptr(pointer __p) : __ptr_(__p) {
+    static_assert(!is_pointer<deleter_type>::value,
+                  "unique_ptr constructed with null function pointer deleter");
+  }
 
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(unique_ptr&& __u) _NOEXCEPT
-        : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {}
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(pointer __p, deleter_type __d)
+      : __ptr_(__p, _VSTD::forward<deleter_type>(__d)) {}
 
-    _LIBCPP_INLINE_VISIBILITY unique_ptr& operator=(unique_ptr&& __u) _NOEXCEPT
-        {
-            reset(__u.release());
-            __ptr_.second() = _VSTD::forward<deleter_type>(__u.get_deleter());
-            return *this;
-        }
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(nullptr_t, deleter_type __d)
+      : __ptr_(pointer(), _VSTD::forward<deleter_type>(__d)) {}
 
-    template <class _Up, class _Ep>
-        _LIBCPP_INLINE_VISIBILITY
-        unique_ptr(unique_ptr<_Up, _Ep>&& __u,
-                   typename enable_if
-                            <
-                                is_array<_Up>::value &&
-                                __same_or_less_cv_qualified<typename unique_ptr<_Up, _Ep>::pointer, pointer>::value
-                                && is_convertible<_Ep, deleter_type>::value &&
-                                (
-                                    !is_reference<deleter_type>::value ||
-                                    is_same<deleter_type, _Ep>::value
-                                ),
-                                __nat
-                            >::type = __nat()
-                  ) _NOEXCEPT
-        : __ptr_(__u.release(), _VSTD::forward<deleter_type>(__u.get_deleter())) {}
-
-
-        template <class _Up, class _Ep>
-            _LIBCPP_INLINE_VISIBILITY
-            typename enable_if
-            <
-                is_array<_Up>::value &&
-                __same_or_less_cv_qualified<typename unique_ptr<_Up, _Ep>::pointer, pointer>::value &&
-                is_assignable<deleter_type&, _Ep&&>::value,
-                unique_ptr&
-            >::type
-            operator=(unique_ptr<_Up, _Ep>&& __u) _NOEXCEPT
-            {
-                reset(__u.release());
-                __ptr_.second() = _VSTD::forward<_Ep>(__u.get_deleter());
-                return *this;
-            }
-#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+  _LIBCPP_INLINE_VISIBILITY
+  operator __rv<unique_ptr>() {
+    return __rv<unique_ptr>(*this);
+  }
 
-    _LIBCPP_INLINE_VISIBILITY explicit unique_ptr(pointer __p)
-        : __ptr_(__p)
-        {
-            static_assert(!is_pointer<deleter_type>::value,
-                "unique_ptr constructed with null function pointer deleter");
-        }
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr(__rv<unique_ptr> __u)
+      : __ptr_(__u->release(),
+               _VSTD::forward<deleter_type>(__u->get_deleter())) {}
 
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(pointer __p, deleter_type __d)
-        : __ptr_(__p, _VSTD::forward<deleter_type>(__d)) {}
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr& operator=(__rv<unique_ptr> __u) {
+    reset(__u->release());
+    __ptr_.second() = _VSTD::forward<deleter_type>(__u->get_deleter());
+    return *this;
+  }
 
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(nullptr_t, deleter_type __d)
-        : __ptr_(pointer(), _VSTD::forward<deleter_type>(__d)) {}
+#endif // _LIBCPP_CXX03_LANG
 
-    _LIBCPP_INLINE_VISIBILITY operator __rv<unique_ptr>()
-    {
-        return __rv<unique_ptr>(*this);
-    }
+public:
+  _LIBCPP_INLINE_VISIBILITY
+  ~unique_ptr() { reset(); }
 
-    _LIBCPP_INLINE_VISIBILITY unique_ptr(__rv<unique_ptr> __u)
-        : __ptr_(__u->release(), _VSTD::forward<deleter_type>(__u->get_deleter())) {}
+  _LIBCPP_INLINE_VISIBILITY
+  unique_ptr& operator=(nullptr_t) _NOEXCEPT {
+    reset();
+    return *this;
+  }
 
-    _LIBCPP_INLINE_VISIBILITY unique_ptr& operator=(__rv<unique_ptr> __u)
-    {
-        reset(__u->release());
-        __ptr_.second() = _VSTD::forward<deleter_type>(__u->get_deleter());
-        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();
+  }
 
-#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
-    _LIBCPP_INLINE_VISIBILITY ~unique_ptr() {reset();}
+  _LIBCPP_INLINE_VISIBILITY
+  deleter_type& get_deleter() _NOEXCEPT {
+    return __ptr_.second();
+  }
 
-    _LIBCPP_INLINE_VISIBILITY unique_ptr& operator=(nullptr_t) _NOEXCEPT
-    {
-        reset();
-        return *this;
-    }
+  _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 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       _Dp_reference get_deleter() _NOEXCEPT
-        {return __ptr_.second();}
-    _LIBCPP_INLINE_VISIBILITY _Dp_const_reference 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 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);
+  }
 
-    template <class _Pp>
-    _LIBCPP_INLINE_VISIBILITY
-    typename enable_if<__same_or_less_cv_qualified<_Pp, pointer>::value, void>::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 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) {__ptr_.swap(__u.__ptr_);}
-private:
+  _LIBCPP_INLINE_VISIBILITY
+  void swap(unique_ptr& __u) _NOEXCEPT {
+    __ptr_.swap(__u.__ptr_);
+  }
 
-#ifdef _LIBCPP_HAS_NO_RVALUE_REFERENCES
-    template <class _Up>
-        explicit unique_ptr(_Up);
-    template <class _Up>
-        unique_ptr(_Up __u,
-                   typename conditional<
-                                       is_reference<deleter_type>::value,
-                                       deleter_type,
-                                       typename add_lvalue_reference<const deleter_type>::type>::type,
-                   typename enable_if
-                      <
-                         is_convertible<_Up, pointer>::value,
-                         __nat
-                      >::type = __nat());
-#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
 };
 
 template <class _Tp, class _Dp>
@@ -3021,365 +3041,18 @@ template<class _Tp, class... _Args>
 
 #endif  // _LIBCPP_STD_VER > 11
 
-template <class _Size>
-inline _LIBCPP_INLINE_VISIBILITY
-_Size
-__loadword(const void* __p)
-{
-    _Size __r;
-    std::memcpy(&__r, __p, sizeof(__r));
-    return __r;
-}
-
-// We use murmur2 when size_t is 32 bits, and cityhash64 when size_t
-// is 64 bits.  This is because cityhash64 uses 64bit x 64bit
-// multiplication, which can be very slow on 32-bit systems.
-template <class _Size, size_t = sizeof(_Size)*__CHAR_BIT__>
-struct __murmur2_or_cityhash;
-
-template <class _Size>
-struct __murmur2_or_cityhash<_Size, 32>
-{
-    _Size operator()(const void* __key, _Size __len);
-};
-
-// murmur2
-template <class _Size>
-_Size
-__murmur2_or_cityhash<_Size, 32>::operator()(const void* __key, _Size __len) _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK 
-{
-    const _Size __m = 0x5bd1e995;
-    const _Size __r = 24;
-    _Size __h = __len;
-    const unsigned char* __data = static_cast<const unsigned char*>(__key);
-    for (; __len >= 4; __data += 4, __len -= 4)
-    {
-        _Size __k = __loadword<_Size>(__data);
-        __k *= __m;
-        __k ^= __k >> __r;
-        __k *= __m;
-        __h *= __m;
-        __h ^= __k;
-    }
-    switch (__len)
-    {
-    case 3:
-        __h ^= __data[2] << 16;
-    case 2:
-        __h ^= __data[1] << 8;
-    case 1:
-        __h ^= __data[0];
-        __h *= __m;
-    }
-    __h ^= __h >> 13;
-    __h *= __m;
-    __h ^= __h >> 15;
-    return __h;
-}
-
-template <class _Size>
-struct __murmur2_or_cityhash<_Size, 64>
-{
-    _Size operator()(const void* __key, _Size __len);
-
- private:
-  // Some primes between 2^63 and 2^64.
-  static const _Size __k0 = 0xc3a5c85c97cb3127ULL;
-  static const _Size __k1 = 0xb492b66fbe98f273ULL;
-  static const _Size __k2 = 0x9ae16a3b2f90404fULL;
-  static const _Size __k3 = 0xc949d7c7509e6557ULL;
-
-  static _Size __rotate(_Size __val, int __shift) {
-    return __shift == 0 ? __val : ((__val >> __shift) | (__val << (64 - __shift)));
-  }
-
-  static _Size __rotate_by_at_least_1(_Size __val, int __shift) {
-    return (__val >> __shift) | (__val << (64 - __shift));
-  }
-
-  static _Size __shift_mix(_Size __val) {
-    return __val ^ (__val >> 47);
-  }
-
-  static _Size __hash_len_16(_Size __u, _Size __v) {
-    const _Size __mul = 0x9ddfea08eb382d69ULL;
-    _Size __a = (__u ^ __v) * __mul;
-    __a ^= (__a >> 47);
-    _Size __b = (__v ^ __a) * __mul;
-    __b ^= (__b >> 47);
-    __b *= __mul;
-    return __b;
-  }
-
-  static _Size __hash_len_0_to_16(const char* __s, _Size __len) {
-    if (__len > 8) {
-      const _Size __a = __loadword<_Size>(__s);
-      const _Size __b = __loadword<_Size>(__s + __len - 8);
-      return __hash_len_16(__a, __rotate_by_at_least_1(__b + __len, __len)) ^ __b;
-    }
-    if (__len >= 4) {
-      const uint32_t __a = __loadword<uint32_t>(__s);
-      const uint32_t __b = __loadword<uint32_t>(__s + __len - 4);
-      return __hash_len_16(__len + (__a << 3), __b);
-    }
-    if (__len > 0) {
-      const unsigned char __a = __s[0];
-      const unsigned char __b = __s[__len >> 1];
-      const unsigned char __c = __s[__len - 1];
-      const uint32_t __y = static_cast<uint32_t>(__a) +
-                           (static_cast<uint32_t>(__b) << 8);
-      const uint32_t __z = __len + (static_cast<uint32_t>(__c) << 2);
-      return __shift_mix(__y * __k2 ^ __z * __k3) * __k2;
-    }
-    return __k2;
-  }
-
-  static _Size __hash_len_17_to_32(const char *__s, _Size __len) {
-    const _Size __a = __loadword<_Size>(__s) * __k1;
-    const _Size __b = __loadword<_Size>(__s + 8);
-    const _Size __c = __loadword<_Size>(__s + __len - 8) * __k2;
-    const _Size __d = __loadword<_Size>(__s + __len - 16) * __k0;
-    return __hash_len_16(__rotate(__a - __b, 43) + __rotate(__c, 30) + __d,
-                         __a + __rotate(__b ^ __k3, 20) - __c + __len);
-  }
-
-  // Return a 16-byte hash for 48 bytes.  Quick and dirty.
-  // Callers do best to use "random-looking" values for a and b.
-  static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
-      _Size __w, _Size __x, _Size __y, _Size __z, _Size __a, _Size __b) {
-    __a += __w;
-    __b = __rotate(__b + __a + __z, 21);
-    const _Size __c = __a;
-    __a += __x;
-    __a += __y;
-    __b += __rotate(__a, 44);
-    return pair<_Size, _Size>(__a + __z, __b + __c);
-  }
-
-  // Return a 16-byte hash for s[0] ... s[31], a, and b.  Quick and dirty.
-  static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
-      const char* __s, _Size __a, _Size __b) {
-    return __weak_hash_len_32_with_seeds(__loadword<_Size>(__s),
-                                         __loadword<_Size>(__s + 8),
-                                         __loadword<_Size>(__s + 16),
-                                         __loadword<_Size>(__s + 24),
-                                         __a,
-                                         __b);
-  }
-
-  // Return an 8-byte hash for 33 to 64 bytes.
-  static _Size __hash_len_33_to_64(const char *__s, size_t __len) {
-    _Size __z = __loadword<_Size>(__s + 24);
-    _Size __a = __loadword<_Size>(__s) +
-                (__len + __loadword<_Size>(__s + __len - 16)) * __k0;
-    _Size __b = __rotate(__a + __z, 52);
-    _Size __c = __rotate(__a, 37);
-    __a += __loadword<_Size>(__s + 8);
-    __c += __rotate(__a, 7);
-    __a += __loadword<_Size>(__s + 16);
-    _Size __vf = __a + __z;
-    _Size __vs = __b + __rotate(__a, 31) + __c;
-    __a = __loadword<_Size>(__s + 16) + __loadword<_Size>(__s + __len - 32);
-    __z += __loadword<_Size>(__s + __len - 8);
-    __b = __rotate(__a + __z, 52);
-    __c = __rotate(__a, 37);
-    __a += __loadword<_Size>(__s + __len - 24);
-    __c += __rotate(__a, 7);
-    __a += __loadword<_Size>(__s + __len - 16);
-    _Size __wf = __a + __z;
-    _Size __ws = __b + __rotate(__a, 31) + __c;
-    _Size __r = __shift_mix((__vf + __ws) * __k2 + (__wf + __vs) * __k0);
-    return __shift_mix(__r * __k0 + __vs) * __k2;
-  }
-};
-
-// cityhash64
-template <class _Size>
-_Size
-__murmur2_or_cityhash<_Size, 64>::operator()(const void* __key, _Size __len) _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK 
-{
-  const char* __s = static_cast<const char*>(__key);
-  if (__len <= 32) {
-    if (__len <= 16) {
-      return __hash_len_0_to_16(__s, __len);
-    } else {
-      return __hash_len_17_to_32(__s, __len);
-    }
-  } else if (__len <= 64) {
-    return __hash_len_33_to_64(__s, __len);
-  }
-
-  // For strings over 64 bytes we hash the end first, and then as we
-  // loop we keep 56 bytes of state: v, w, x, y, and z.
-  _Size __x = __loadword<_Size>(__s + __len - 40);
-  _Size __y = __loadword<_Size>(__s + __len - 16) +
-              __loadword<_Size>(__s + __len - 56);
-  _Size __z = __hash_len_16(__loadword<_Size>(__s + __len - 48) + __len,
-                          __loadword<_Size>(__s + __len - 24));
-  pair<_Size, _Size> __v = __weak_hash_len_32_with_seeds(__s + __len - 64, __len, __z);
-  pair<_Size, _Size> __w = __weak_hash_len_32_with_seeds(__s + __len - 32, __y + __k1, __x);
-  __x = __x * __k1 + __loadword<_Size>(__s);
-
-  // Decrease len to the nearest multiple of 64, and operate on 64-byte chunks.
-  __len = (__len - 1) & ~static_cast<_Size>(63);
-  do {
-    __x = __rotate(__x + __y + __v.first + __loadword<_Size>(__s + 8), 37) * __k1;
-    __y = __rotate(__y + __v.second + __loadword<_Size>(__s + 48), 42) * __k1;
-    __x ^= __w.second;
-    __y += __v.first + __loadword<_Size>(__s + 40);
-    __z = __rotate(__z + __w.first, 33) * __k1;
-    __v = __weak_hash_len_32_with_seeds(__s, __v.second * __k1, __x + __w.first);
-    __w = __weak_hash_len_32_with_seeds(__s + 32, __z + __w.second,
-                                        __y + __loadword<_Size>(__s + 16));
-    std::swap(__z, __x);
-    __s += 64;
-    __len -= 64;
-  } while (__len != 0);
-  return __hash_len_16(
-      __hash_len_16(__v.first, __w.first) + __shift_mix(__y) * __k1 + __z,
-      __hash_len_16(__v.second, __w.second) + __x);
-}
-
-template <class _Tp, size_t = sizeof(_Tp) / sizeof(size_t)>
-struct __scalar_hash;
-
-template <class _Tp>
-struct __scalar_hash<_Tp, 0>
-    : public unary_function<_Tp, size_t>
-{
-    _LIBCPP_INLINE_VISIBILITY
-    size_t operator()(_Tp __v) const _NOEXCEPT
-    {
-        union
-        {
-            _Tp    __t;
-            size_t __a;
-        } __u;
-        __u.__a = 0;
-        __u.__t = __v;
-        return __u.__a;
-    }
-};
-
-template <class _Tp>
-struct __scalar_hash<_Tp, 1>
-    : public unary_function<_Tp, size_t>
-{
-    _LIBCPP_INLINE_VISIBILITY
-    size_t operator()(_Tp __v) const _NOEXCEPT
-    {
-        union
-        {
-            _Tp    __t;
-            size_t __a;
-        } __u;
-        __u.__t = __v;
-        return __u.__a;
-    }
-};
-
-template <class _Tp>
-struct __scalar_hash<_Tp, 2>
-    : public unary_function<_Tp, size_t>
-{
-    _LIBCPP_INLINE_VISIBILITY
-    size_t operator()(_Tp __v) const _NOEXCEPT
-    {
-        union
-        {
-            _Tp __t;
-            struct
-            {
-                size_t __a;
-                size_t __b;
-            } __s;
-        } __u;
-        __u.__t = __v;
-        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
-    }
-};
-
-template <class _Tp>
-struct __scalar_hash<_Tp, 3>
-    : public unary_function<_Tp, size_t>
-{
-    _LIBCPP_INLINE_VISIBILITY
-    size_t operator()(_Tp __v) const _NOEXCEPT
-    {
-        union
-        {
-            _Tp __t;
-            struct
-            {
-                size_t __a;
-                size_t __b;
-                size_t __c;
-            } __s;
-        } __u;
-        __u.__t = __v;
-        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
-    }
-};
-
-template <class _Tp>
-struct __scalar_hash<_Tp, 4>
-    : public unary_function<_Tp, size_t>
-{
-    _LIBCPP_INLINE_VISIBILITY
-    size_t operator()(_Tp __v) const _NOEXCEPT
-    {
-        union
-        {
-            _Tp __t;
-            struct
-            {
-                size_t __a;
-                size_t __b;
-                size_t __c;
-                size_t __d;
-            } __s;
-        } __u;
-        __u.__t = __v;
-        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
-    }
-};
-
-struct _PairT {
-  size_t first;
-  size_t second;
-};
-
-_LIBCPP_INLINE_VISIBILITY
-inline size_t __hash_combine(size_t __lhs, size_t __rhs) _NOEXCEPT {
-    typedef __scalar_hash<_PairT> _HashT;
-    const _PairT __p = {__lhs, __rhs};
-    return _HashT()(__p);
-}
-
-template<class _Tp>
-struct _LIBCPP_TEMPLATE_VIS hash<_Tp*>
-    : public unary_function<_Tp*, size_t>
-{
-    _LIBCPP_INLINE_VISIBILITY
-    size_t operator()(_Tp* __v) const _NOEXCEPT
-    {
-        union
-        {
-            _Tp* __t;
-            size_t __a;
-        } __u;
-        __u.__t = __v;
-        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
-    }
-};
-
 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 _NOEXCEPT
+    result_type operator()(const argument_type& __ptr) const
     {
         typedef typename argument_type::pointer pointer;
         return hash<pointer>()(__ptr.get());
@@ -3389,28 +3062,28 @@ struct _LIBCPP_TEMPLATE_VIS hash<unique_ptr<_Tp, _Dp> >
 struct __destruct_n
 {
 private:
-    size_t size;
+    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();}
+        {for (size_t __i = 0; __i < __size_; ++__i, ++__p) __p->~_Tp();}
 
     template <class _Tp>
     _LIBCPP_INLINE_VISIBILITY void __process(_Tp*, true_type) _NOEXCEPT
         {}
 
     _LIBCPP_INLINE_VISIBILITY void __incr(false_type) _NOEXCEPT
-        {++size;}
+        {++__size_;}
     _LIBCPP_INLINE_VISIBILITY void __incr(true_type) _NOEXCEPT
         {}
 
     _LIBCPP_INLINE_VISIBILITY void __set(size_t __s, false_type) _NOEXCEPT
-        {size = __s;}
+        {__size_ = __s;}
     _LIBCPP_INLINE_VISIBILITY void __set(size_t, true_type) _NOEXCEPT
         {}
 public:
     _LIBCPP_INLINE_VISIBILITY explicit __destruct_n(size_t __s) _NOEXCEPT
-        : size(__s) {}
+        : __size_(__s) {}
 
     template <class _Tp>
     _LIBCPP_INLINE_VISIBILITY void __incr(_Tp*) _NOEXCEPT
@@ -3681,6 +3354,39 @@ uninitialized_move_n(_InputIt __first, _Size __n, _ForwardIt __first_res) {
 
 #endif // _LIBCPP_STD_VER > 14
 
+// NOTE: Relaxed and acq/rel atomics (for increment and decrement respectively)
+// should be sufficient for thread safety.
+// See https://bugs.llvm.org/show_bug.cgi?id=22803
+#if defined(__clang__) && __has_builtin(__atomic_add_fetch)          \
+                       && defined(__ATOMIC_RELAXED)                  \
+                       && defined(__ATOMIC_ACQ_REL)
+#   define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT
+#elif !defined(__clang__) && defined(_GNUC_VER) && _GNUC_VER >= 407
+#   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
 {
@@ -3717,8 +3423,24 @@ public:
     explicit __shared_count(long __refs = 0) _NOEXCEPT
         : __shared_owners_(__refs) {}
 
+#if defined(_LIBCPP_BUILDING_MEMORY) && \
+    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;
@@ -3739,9 +3461,26 @@ protected:
     virtual ~__shared_weak_count();
 
 public:
+#if defined(_LIBCPP_BUILDING_MEMORY) && \
+    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();}
@@ -3783,7 +3522,7 @@ 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()) : 0;
+    return __t == typeid(_Dp) ? _VSTD::addressof(__data_.first().second()) : nullptr;
 }
 
 #endif  // _LIBCPP_NO_RTTI
@@ -3877,6 +3616,18 @@ __shared_ptr_emplace<_Tp, _Alloc>::__on_zero_shared_weak() _NOEXCEPT
     __a.deallocate(_PTraits::pointer_to(*this), 1);
 }
 
+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>
@@ -3926,6 +3677,7 @@ public:
 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
     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)
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     template<class _Yp>
         shared_ptr(auto_ptr<_Yp>&& __r,
@@ -3935,6 +3687,7 @@ public:
         shared_ptr(auto_ptr<_Yp> __r,
                    typename enable_if<is_convertible<_Yp*, element_type*>::value, __nat>::type = __nat());
 #endif
+#endif
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     template <class _Yp, class _Dp>
         shared_ptr(unique_ptr<_Yp, _Dp>&&,
@@ -3998,6 +3751,7 @@ public:
         >::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
@@ -4007,7 +3761,9 @@ public:
             shared_ptr
         >::type&
         operator=(auto_ptr<_Yp>&& __r);
+#endif
 #else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
     template<class _Yp>
         _LIBCPP_INLINE_VISIBILITY
         typename enable_if
@@ -4018,6 +3774,7 @@ public:
         >::type
         operator=(auto_ptr<_Yp> __r);
 #endif
+#endif
     template <class _Yp, class _Dp>
         typename enable_if
         <
@@ -4077,11 +3834,11 @@ public:
     _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT {return get() != 0;}
     template <class _Up>
         _LIBCPP_INLINE_VISIBILITY
-        bool owner_before(shared_ptr<_Up> const& __p) const
+        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
+        bool owner_before(weak_ptr<_Up> const& __p) const _NOEXCEPT
         {return __cntrl_ < __p.__cntrl_;}
     _LIBCPP_INLINE_VISIBILITY
     bool
@@ -4092,7 +3849,9 @@ public:
     template <class _Dp>
         _LIBCPP_INLINE_VISIBILITY
         _Dp* __get_deleter() const _NOEXCEPT
-            {return (_Dp*)(__cntrl_ ? __cntrl_->__get_deleter(typeid(_Dp)) : 0);}
+            {return static_cast<_Dp*>(__cntrl_
+                    ? const_cast<void *>(__cntrl_->__get_deleter(typeid(_Dp))) 
+                      : nullptr);}
 #endif  // _LIBCPP_NO_RTTI
 
 #ifndef _LIBCPP_HAS_NO_VARIADICS
@@ -4139,10 +3898,24 @@ public:
 #endif  // _LIBCPP_HAS_NO_VARIADICS
 
 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
-        void
+        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
         {
@@ -4154,13 +3927,13 @@ private:
             }
         }
 
-    _LIBCPP_INLINE_VISIBILITY
-    void __enable_weak_this(const volatile void*, const volatile void*) _NOEXCEPT {}
+    _LIBCPP_INLINE_VISIBILITY void __enable_weak_this(...) _NOEXCEPT {}
 
     template <class _Up> friend class _LIBCPP_TEMPLATE_VIS shared_ptr;
     template <class _Up> friend class _LIBCPP_TEMPLATE_VIS weak_ptr;
 };
 
+
 template<class _Tp>
 inline
 _LIBCPP_CONSTEXPR
@@ -4186,8 +3959,9 @@ shared_ptr<_Tp>::shared_ptr(_Yp* __p,
     : __ptr_(__p)
 {
     unique_ptr<_Yp> __hold(__p);
-    typedef __shared_ptr_pointer<_Yp*, default_delete<_Yp>, allocator<_Yp> > _CntrlBlk;
-    __cntrl_ = new _CntrlBlk(__p, default_delete<_Yp>(), allocator<_Yp>());
+    typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
+    typedef __shared_ptr_pointer<_Yp*, default_delete<_Yp>, _AllocT > _CntrlBlk;
+    __cntrl_ = new _CntrlBlk(__p, default_delete<_Yp>(), _AllocT());
     __hold.release();
     __enable_weak_this(__p, __p);
 }
@@ -4202,8 +3976,9 @@ shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d,
     try
     {
 #endif  // _LIBCPP_NO_EXCEPTIONS
-        typedef __shared_ptr_pointer<_Yp*, _Dp, allocator<_Yp> > _CntrlBlk;
-        __cntrl_ = new _CntrlBlk(__p, __d, allocator<_Yp>());
+        typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
+        typedef __shared_ptr_pointer<_Yp*, _Dp, _AllocT > _CntrlBlk;
+        __cntrl_ = new _CntrlBlk(__p, __d, _AllocT());
         __enable_weak_this(__p, __p);
 #ifndef _LIBCPP_NO_EXCEPTIONS
     }
@@ -4224,8 +3999,9 @@ shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d)
     try
     {
 #endif  // _LIBCPP_NO_EXCEPTIONS
-        typedef __shared_ptr_pointer<nullptr_t, _Dp, allocator<_Tp> > _CntrlBlk;
-        __cntrl_ = new _CntrlBlk(__p, __d, allocator<_Tp>());
+        typedef typename __shared_ptr_default_allocator<_Tp>::type _AllocT;
+        typedef __shared_ptr_pointer<nullptr_t, _Dp, _AllocT > _CntrlBlk;
+        __cntrl_ = new _CntrlBlk(__p, __d, _AllocT());
 #ifndef _LIBCPP_NO_EXCEPTIONS
     }
     catch (...)
@@ -4353,6 +4129,7 @@ shared_ptr<_Tp>::shared_ptr(shared_ptr<_Yp>&& __r,
 
 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
 
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
 template<class _Tp>
 template<class _Yp>
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
@@ -4368,6 +4145,7 @@ shared_ptr<_Tp>::shared_ptr(auto_ptr<_Yp> __r,
     __enable_weak_this(__r.get(), __r.get());
     __r.release();
 }
+#endif
 
 template<class _Tp>
 template <class _Yp, class _Dp>
@@ -4391,8 +4169,9 @@ shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp> __r,
     else
 #endif
     {
-        typedef __shared_ptr_pointer<_Yp*, _Dp, allocator<_Yp> > _CntrlBlk;
-        __cntrl_ = new _CntrlBlk(__r.get(), __r.get_deleter(), allocator<_Yp>());
+        typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
+        typedef __shared_ptr_pointer<_Yp*, _Dp, _AllocT > _CntrlBlk;
+        __cntrl_ = new _CntrlBlk(__r.get(), __r.get_deleter(), _AllocT());
         __enable_weak_this(__r.get(), __r.get());
     }
     __r.release();
@@ -4420,10 +4199,11 @@ shared_ptr<_Tp>::shared_ptr(unique_ptr<_Yp, _Dp> __r,
     else
 #endif
     {
+        typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
         typedef __shared_ptr_pointer<_Yp*,
                                      reference_wrapper<typename remove_reference<_Dp>::type>,
-                                     allocator<_Yp> > _CntrlBlk;
-        __cntrl_ = new _CntrlBlk(__r.get(), ref(__r.get_deleter()), allocator<_Yp>());
+                                     _AllocT > _CntrlBlk;
+        __cntrl_ = new _CntrlBlk(__r.get(), ref(__r.get_deleter()), _AllocT());
         __enable_weak_this(__r.get(), __r.get());
     }
     __r.release();
@@ -4674,6 +4454,7 @@ shared_ptr<_Tp>::operator=(shared_ptr<_Yp>&& __r)
     return *this;
 }
 
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
 template<class _Tp>
 template<class _Yp>
 inline
@@ -4688,6 +4469,7 @@ 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>
@@ -4707,6 +4489,7 @@ shared_ptr<_Tp>::operator=(unique_ptr<_Yp, _Dp>&& __r)
 
 #else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
 
+#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
 template<class _Tp>
 template<class _Yp>
 inline _LIBCPP_INLINE_VISIBILITY
@@ -4721,6 +4504,7 @@ shared_ptr<_Tp>::operator=(auto_ptr<_Yp> __r)
     shared_ptr(__r).swap(*this);
     return *this;
 }
+#endif
 
 template<class _Tp>
 template <class _Yp, class _Dp>
@@ -5171,11 +4955,11 @@ public:
     shared_ptr<_Tp> lock() const _NOEXCEPT;
     template<class _Up>
         _LIBCPP_INLINE_VISIBILITY
-        bool owner_before(const shared_ptr<_Up>& __r) const
+        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
+        bool owner_before(const weak_ptr<_Up>& __r) const _NOEXCEPT
         {return __cntrl_ < __r.__cntrl_;}
 
     template <class _Up> friend class _LIBCPP_TEMPLATE_VIS weak_ptr;
@@ -5384,13 +5168,13 @@ struct _LIBCPP_TEMPLATE_VIS owner_less<shared_ptr<_Tp> >
 {
     typedef bool result_type;
     _LIBCPP_INLINE_VISIBILITY
-    bool operator()(shared_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const
+    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
+    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
+    bool operator()(  weak_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const _NOEXCEPT
         {return __x.owner_before(__y);}
 };
 
@@ -5400,13 +5184,13 @@ struct _LIBCPP_TEMPLATE_VIS owner_less<weak_ptr<_Tp> >
 {
     typedef bool result_type;
     _LIBCPP_INLINE_VISIBILITY
-    bool operator()(  weak_ptr<_Tp> const& __x,   weak_ptr<_Tp> const& __y) const
+    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
+    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
+    bool operator()(  weak_ptr<_Tp> const& __x, shared_ptr<_Tp> const& __y) const _NOEXCEPT
         {return __x.owner_before(__y);}
 };
 
@@ -5416,19 +5200,19 @@ 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
+    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
+    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
+    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
+    bool operator()(   weak_ptr<_Tp> const& __x,   weak_ptr<_Up> const& __y) const _NOEXCEPT
         {return __x.owner_before(__y);}
     typedef void is_transparent;
 };
@@ -5474,6 +5258,7 @@ 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
     {
@@ -5504,7 +5289,8 @@ private:
     friend _LIBCPP_FUNC_VIS __sp_mut& __get_sp_mut(const void*);
 };
 
-_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
@@ -5515,6 +5301,7 @@ atomic_is_lock_free(const shared_ptr<_Tp>*)
 }
 
 template <class _Tp>
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 shared_ptr<_Tp>
 atomic_load(const shared_ptr<_Tp>* __p)
 {
@@ -5527,6 +5314,7 @@ atomic_load(const shared_ptr<_Tp>* __p)
   
 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)
 {
@@ -5534,6 +5322,7 @@ atomic_load_explicit(const shared_ptr<_Tp>* __p, memory_order)
 }
 
 template <class _Tp>
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 void
 atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
 {
@@ -5545,6 +5334,7 @@ atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
 
 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)
 {
@@ -5552,6 +5342,7 @@ atomic_store_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order)
 }
 
 template <class _Tp>
+_LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
 shared_ptr<_Tp>
 atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r)
 {
@@ -5564,6 +5355,7 @@ atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __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)
 {
@@ -5571,6 +5363,7 @@ atomic_exchange_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r, memory_order
 }
 
 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)
 {
@@ -5592,6 +5385,7 @@ atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, share
 
 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)
 {
@@ -5600,6 +5394,7 @@ atomic_compare_exchange_weak(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* __v, shared_
 
 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)
@@ -5609,6 +5404,7 @@ atomic_compare_exchange_strong_explicit(shared_ptr<_Tp>* __p, shared_ptr<_Tp>* _
 
 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)
@@ -5741,4 +5537,6 @@ struct __temp_value {
 
 _LIBCPP_END_NAMESPACE_STD
 
+_LIBCPP_POP_MACROS
+
 #endif  // _LIBCPP_MEMORY