[libc++] fix `shared_ptr`'s incorrect constraints

[huixie90]

Summary

Fix several bugs:

1. https://llvm.org/PR60258 The conversion constructors' constraint __compatible_with incorrectly allow array types conversion to scalar types
2. https://llvm.org/PR53368 The constructor that takes unique_ptr are not suffiently constrained.
3. The constructors that take raw pointers incorretly use __compatible_with. They have different constraints

[huixie90]

update commit msg

[huixie90]

CI

[huixie90]

CI

[huixie90]

ci

[huixie90]

CI

[ldionne]

Thanks for fixing this! Only nits.

Let's land this and cherry-pick it onto LLVM 16. Please add a release note on the LLVM 16 release branch to explain that this constrains std::shared_ptr more than it used to, which could lead to a bit of source break. I don't think this should be too big of a deal, especially since the code this would break is arguably brittle.

Pinging vendors for awareness.

libcxx/include/__memory/shared_ptr.h

373

374–380

Along with (optionally) a test case for why this can't be implemented by inheriting from _BoolConstant.

382

Same here, let's use _Tp instead of _Tp2.

392

792

Can you double-check whether this should be element_type or _Tp?

[rupprecht]

In D143346#4113858, @ldionne wrote:

Thanks for fixing this! Only nits.

Let's land this and cherry-pick it onto LLVM 16. Please add a release note on the LLVM 16 release branch to explain that this constrains std::shared_ptr more than it used to, which could lead to a bit of source break. I don't think this should be too big of a deal, especially since the code this would break is arguably brittle.

Pinging vendors for awareness.

Thanks for the ping, @ldionne. As usual, this causes a few breakages for us, but they're all trivial to fix. No concerns from me to land this whenever you're ready.

[ldionne]

In D143346#4117099, @rupprecht wrote:

In D143346#4113858, @ldionne wrote:

Thanks for fixing this! Only nits.

Let's land this and cherry-pick it onto LLVM 16. Please add a release note on the LLVM 16 release branch to explain that this constrains std::shared_ptr more than it used to, which could lead to a bit of source break. I don't think this should be too big of a deal, especially since the code this would break is arguably brittle.

Pinging vendors for awareness.

Thanks for the ping, @ldionne. As usual, this causes a few breakages for us, but they're all trivial to fix. No concerns from me to land this whenever you're ready.

Thanks a lot for checking!

[huixie90]

address comments

libcxx/include/__memory/shared_ptr.h

public:
     struct rebind
     {
         typedef allocator<_Other> other;
     };
 };
 
 template<class _Tp> class _LIBCPP_TEMPLATE_VIS enable_shared_from_this;
 
-template<class _Tp, class _Up>
+// http://eel.is/c++draft/util.sharedptr#util.smartptr.shared.general-6
+// A pointer type Y* is said to be compatible with a pointer type T*
+// when either Y* is convertible to T* or Y is U[N] and T is cv U[].
+#if _LIBCPP_STD_VER > 14
+template <class _Yp, class _Tp2, class = void>
+struct __bounded_convertible_to_unbounded : false_type {};
+
+template <class _Up, std::size_t _Np, class _Tp2>
+struct __bounded_convertible_to_unbounded<_Up[_Np], _Tp2,
+            __enable_if_t<__is_same(__remove_cv_t<_Tp2>, _Up[])>>
+        : true_type {};
+
+template <class _Yp, class _Tp2>
 struct __compatible_with
+    : _Or<
+        is_convertible<_Yp*, _Tp2*>,
+        __bounded_convertible_to_unbounded<_Yp, _Tp2>
+    > {};
+#else
+template <class _Yp, class _Tp2>
+struct __compatible_with
+    : is_convertible<_Yp*, _Tp2*> {};
+#endif // _LIBCPP_STD_VER > 14
+
+// Constructors that take raw pointers have a different set of "compatible" constraints
+// http://eel.is/c++draft/util.sharedptr#util.smartptr.shared.const-9.1
+// - If T is an array type, then either T is U[N] and Y(*)[N] is convertible to T*,
+//   or T is U[] and Y(*)[] is convertible to T*.
+// - If T is not an array type, then Y* is convertible to T*.
 #if _LIBCPP_STD_VER > 14
-    : is_convertible<remove_extent_t<_Tp>*, remove_extent_t<_Up>*> {};
+template <class _Yp, class _Tp2, class = void>
+struct __raw_pointer_compatible_with : _And<
+        _Not<is_array<_Tp2>>,
+        is_convertible<_Yp*, _Tp2*>
+        > {};
+
+template <class _Yp, class _Up, std::size_t _Np>
+struct __raw_pointer_compatible_with<_Yp, _Up[_Np], __enable_if_t<
+            is_convertible<_Yp(*)[_Np], _Up(*)[_Np]>::value> >
+        : true_type {};
+
+template <class _Yp, class _Up>
+struct __raw_pointer_compatible_with<_Yp, _Up[], __enable_if_t<
+            is_convertible<_Yp(*)[], _Up(*)[]>::value> >
+        : true_type {};
+
 #else
-    : is_convertible<_Tp*, _Up*> {};
+template <class _Yp, class _Tp2>
+struct __raw_pointer_compatible_with
+    : is_convertible<_Yp*, _Tp2*> {};
 #endif // _LIBCPP_STD_VER > 14
 
+
 template <class _Ptr, class = void>
 struct __is_deletable : false_type { };
 template <class _Ptr>
 struct __is_deletable<_Ptr, decltype(delete std::declval<_Ptr>())> : true_type { };
 
 template <class _Ptr, class = void>
 struct __is_array_deletable : false_type { };
 template <class _Ptr>
 struct __is_array_deletable<_Ptr, decltype(delete[] std::declval<_Ptr>())> : true_type { };
 
 template <class _Dp, class _Pt,
     class = decltype(std::declval<_Dp>()(std::declval<_Pt>()))>
 static true_type __well_formed_deleter_test(int);
 
 template <class, class>
 static false_type __well_formed_deleter_test(...);
 
 template <class _Dp, class _Pt>
 struct __well_formed_deleter : decltype(std::__well_formed_deleter_test<_Dp, _Pt>(0)) {};
 
-template<class _Dp, class _Tp, class _Yp>
+template<class _Dp, class _Yp, class _Tp2>
 struct __shared_ptr_deleter_ctor_reqs
 {
-    static const bool value = __compatible_with<_Tp, _Yp>::value &&
+    static const bool value = __raw_pointer_compatible_with<_Yp, _Tp2>::value &&
                               is_move_constructible<_Dp>::value &&
-                              __well_formed_deleter<_Dp, _Tp*>::value;
+                              __well_formed_deleter<_Dp, _Yp*>::value;
 };
 
 #if defined(_LIBCPP_ABI_ENABLE_SHARED_PTR_TRIVIAL_ABI)
 #  define _LIBCPP_SHARED_PTR_TRIVIAL_ABI __attribute__((__trivial_abi__))
 #else
 #  define _LIBCPP_SHARED_PTR_TRIVIAL_ABI
 #endif
 
public:
     _LIBCPP_HIDE_FROM_ABI
     _LIBCPP_CONSTEXPR shared_ptr(nullptr_t) _NOEXCEPT
         : __ptr_(nullptr),
           __cntrl_(nullptr)
     { }
 
     template<class _Yp, class = __enable_if_t<
         _And<
-            __compatible_with<_Yp, _Tp>
+            __raw_pointer_compatible_with<_Yp, _Tp>
             // In C++03 we get errors when trying to do SFINAE with the
             // delete operator, so we always pretend that it's deletable.
             // The same happens on GCC.
 #if !defined(_LIBCPP_CXX03_LANG) && !defined(_LIBCPP_COMPILER_GCC)
             , _If<is_array<_Tp>::value, __is_array_deletable<_Yp*>, __is_deletable<_Yp*> >
 #endif
         >::value
     > >
     explicit shared_ptr(_Yp* __p) : __ptr_(__p) {
         unique_ptr<_Yp> __hold(__p);
         typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
         typedef __shared_ptr_pointer<_Yp*, __shared_ptr_default_delete<_Tp, _Yp>, _AllocT> _CntrlBlk;
         __cntrl_ = new _CntrlBlk(__p, __shared_ptr_default_delete<_Tp, _Yp>(), _AllocT());
         __hold.release();
         __enable_weak_this(__p, __p);
     }
 
-    template<class _Yp, class _Dp, class = __enable_if_t<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value> >
+    template<class _Yp, class _Dp, class = __enable_if_t<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, _Tp>::value> >
     _LIBCPP_HIDE_FROM_ABI
     shared_ptr(_Yp* __p, _Dp __d)
         : __ptr_(__p)
     {
 #ifndef _LIBCPP_NO_EXCEPTIONS
         try
         {
 #endif // _LIBCPP_NO_EXCEPTIONS
#ifndef _LIBCPP_NO_EXCEPTIONS
         catch (...)
         {
             __d(__p);
             throw;
         }
 #endif // _LIBCPP_NO_EXCEPTIONS
     }
 
-    template<class _Yp, class _Dp, class _Alloc, class = __enable_if_t<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, element_type>::value> >
+    template<class _Yp, class _Dp, class _Alloc, class = __enable_if_t<__shared_ptr_deleter_ctor_reqs<_Dp, _Yp, _Tp>::value> >
     _LIBCPP_HIDE_FROM_ABI
     shared_ptr(_Yp* __p, _Dp __d, _Alloc __a)
         : __ptr_(__p)
     {
 #ifndef _LIBCPP_NO_EXCEPTIONS
         try
         {
 #endif // _LIBCPP_NO_EXCEPTIONS
shared_ptr(auto_ptr<_Yp>&& __r)
         __cntrl_ = new _CntrlBlk(__r.get(), default_delete<_Yp>(), allocator<_Yp>());
         __enable_weak_this(__r.get(), __r.get());
         __r.release();
     }
 #endif
 
     template <class _Yp, class _Dp, class = __enable_if_t<
         !is_lvalue_reference<_Dp>::value &&
+         __compatible_with<_Yp, _Tp>::value &&
          is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value
     > >
     _LIBCPP_HIDE_FROM_ABI
     shared_ptr(unique_ptr<_Yp, _Dp>&& __r)
         : __ptr_(__r.get())
     {
 #if _LIBCPP_STD_VER > 11
         if (__ptr_ == nullptr)
             __cntrl_ = nullptr;
         else
 #endif
         {
             typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
             typedef __shared_ptr_pointer<typename unique_ptr<_Yp, _Dp>::pointer, _Dp, _AllocT> _CntrlBlk;
             __cntrl_ = new _CntrlBlk(__r.get(), std::move(__r.get_deleter()), _AllocT());
             __enable_weak_this(__r.get(), __r.get());
         }
         __r.release();
     }
 
     template <class _Yp, class _Dp, class = void, class = __enable_if_t<
         is_lvalue_reference<_Dp>::value &&
+         __compatible_with<_Yp, _Tp>::value &&
         is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value
     > >
     _LIBCPP_HIDE_FROM_ABI
     shared_ptr(unique_ptr<_Yp, _Dp>&& __r)
         : __ptr_(__r.get())
     {
 #if _LIBCPP_STD_VER > 11
         if (__ptr_ == nullptr)
#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
     _LIBCPP_HIDE_FROM_ABI
     shared_ptr<_Tp>& operator=(auto_ptr<_Yp>&& __r)
     {
         shared_ptr(_VSTD::move(__r)).swap(*this);
         return *this;
     }
 #endif
 
-    template <class _Yp, class _Dp, class = __enable_if_t<
-        is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>::value
-    > >
+    template <class _Yp, class _Dp, class = __enable_if_t<_And<
+        __compatible_with<_Yp, _Tp>,
+        is_convertible<typename unique_ptr<_Yp, _Dp>::pointer, element_type*>
+    >::value> >
     _LIBCPP_HIDE_FROM_ABI
     shared_ptr<_Tp>& operator=(unique_ptr<_Yp, _Dp>&& __r)
     {
         shared_ptr(_VSTD::move(__r)).swap(*this);
         return *this;
     }
 
     _LIBCPP_HIDE_FROM_ABI
     void swap(shared_ptr& __r) _NOEXCEPT
     {
         _VSTD::swap(__ptr_, __r.__ptr_);
         _VSTD::swap(__cntrl_, __r.__cntrl_);
     }
 
     _LIBCPP_HIDE_FROM_ABI
     void reset() _NOEXCEPT
     {
         shared_ptr().swap(*this);
     }
 
     template<class _Yp, class = __enable_if_t<
-        __compatible_with<_Yp, _Tp>::value
+        __raw_pointer_compatible_with<_Yp, _Tp>::value
     > >
     _LIBCPP_HIDE_FROM_ABI
     void reset(_Yp* __p)
     {
         shared_ptr(__p).swap(*this);
     }
 
     template<class _Yp, class _Dp, class = __enable_if_t<
-        __compatible_with<_Yp, _Tp>::value
-    > >
+        __shared_ptr_deleter_ctor_reqs<_Dp, _Yp, _Tp>::value> >
     _LIBCPP_HIDE_FROM_ABI
     void reset(_Yp* __p, _Dp __d)
     {
         shared_ptr(__p, __d).swap(*this);
     }
 
     template<class _Yp, class _Dp, class _Alloc, class = __enable_if_t<
-        __compatible_with<_Yp, _Tp>::value
-    > >
+        __shared_ptr_deleter_ctor_reqs<_Dp, _Yp, _Tp>::value> >
     _LIBCPP_HIDE_FROM_ABI
     void reset(_Yp* __p, _Dp __d, _Alloc __a)
     {
         shared_ptr(__p, __d, __a).swap(*this);
     }
 
     _LIBCPP_HIDE_FROM_ABI
     element_type* get() const _NOEXCEPT

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.assign/unique_ptr_Y.pass.cpp

struct StatefulArrayDeleter {
   StatefulArrayDeleter(StatefulArrayDeleter const&) { assert(false); }
 
   void operator()(T* ptr) {
     assert(state == 42);
     delete []ptr;
   }
 };
 
+// https://llvm.org/PR53368
+// Bogus unique_ptr-to-shared_ptr conversions should be forbidden
+#if TEST_STD_VER >= 17
+static_assert( std::is_assignable<std::shared_ptr<A>&,   std::unique_ptr<A>&&>::value, "");
+static_assert( std::is_assignable<std::shared_ptr<A[]>&, std::unique_ptr<A[]>&&>::value, "");
+static_assert(!std::is_assignable<std::shared_ptr<A>&,   std::unique_ptr<A[]>&&>::value, "");
+static_assert(!std::is_assignable<std::shared_ptr<B[]>&, std::unique_ptr<A[]>&&>::value, "");
+static_assert(!std::is_assignable<std::shared_ptr<B>&,   std::unique_ptr<A[]>&&>::value, "");
+#endif
+
 int main(int, char**)
 {
     {
         std::unique_ptr<A> pA(new A);
         A* ptrA = pA.get();
         {
             std::shared_ptr<B> pB(new B);
             pB = std::move(pA);
//          assert(pB.use_count() == 1); // no longer true due to LWG 2415
             assert(pB.get() == ptrA);
         }
         assert(B::count == 0);
         assert(A::count == 0);
     }
     assert(B::count == 0);
     assert(A::count == 0);
 
-#ifdef _LIBCPP_VERSION // https://llvm.org/PR53368
-    {
-      std::unique_ptr<A[]> ptr(new A[8]);
-      A* raw_ptr = ptr.get();
-      std::shared_ptr<B> p;
-      p = std::move(ptr);
-      assert(A::count == 8);
-      assert(B::count == 8);
-      assert(p.use_count() == 1);
-      assert(p.get() == raw_ptr);
-      assert(ptr.get() == 0);
-    }
-    assert(A::count == 0);
-    assert(B::count == 0);
-
-    {
-      std::unique_ptr<A[]> ptr(new A[8]);
-      A* raw_ptr = ptr.get();
-      std::shared_ptr<A> p;
-      p = std::move(ptr);
-      assert(A::count == 8);
-      assert(p.use_count() == 1);
-      assert(p.get() == raw_ptr);
-      assert(ptr.get() == 0);
-    }
-    assert(A::count == 0);
-
-    {
-      std::unique_ptr<int[]> ptr(new int[8]);
-      std::shared_ptr<int> p;
-      p = std::move(ptr);
-    }
-#endif // _LIBCPP_VERSION
-
 #if TEST_STD_VER > 14
     {
       StatefulArrayDeleter<A> d;
       std::unique_ptr<A[], StatefulArrayDeleter<A>&> u(new A[4], d);
       std::shared_ptr<A[]> p;
       p = std::move(u);
       d.state = 42;
       assert(A::count == 4);
     }
     assert(A::count == 0);
     assert(B::count == 0);
 
-#ifdef _LIBCPP_VERSION // https://llvm.org/PR53368
-    {
-      std::unique_ptr<A[]> ptr(new A[8]);
-      A* raw_ptr = ptr.get();
-      std::shared_ptr<B[]> p;
-      p = std::move(ptr);
-      assert(A::count == 8);
-      assert(B::count == 8);
-      assert(p.use_count() == 1);
-      assert(p.get() == raw_ptr);
-      assert(ptr.get() == 0);
-    }
-    assert(A::count == 0);
-    assert(B::count == 0);
-#endif // _LIBCPP_VERSION
-
     {
       std::unique_ptr<A[]> ptr(new A[8]);
       A* raw_ptr = ptr.get();
       std::shared_ptr<A[]> p;
       p = std::move(ptr);
       assert(A::count == 8);
       assert(p.use_count() == 1);
       assert(p.get() == raw_ptr);

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/pointer.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // <memory>
 
 // template<class Y> explicit shared_ptr(Y* p);
 
-#include <memory>
 #include <cassert>
+#include <memory>
+#include <type_traits>
 
 #include "test_macros.h"
 
 struct A
 {
     static int count;
 
     A() {++count;}
     A(const A&) {++count;}
     ~A() {--count;}
 };
 
 int A::count = 0;
 
+struct Derived : A {};
+
+// https://llvm.org/PR60258
+// Invalid constructor SFINAE for std::shared_ptr's array ctors
+static_assert( std::is_constructible<std::shared_ptr<int>,  int*>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<A>,  Derived*>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<A>,  int*>::value, "");
+
+#if TEST_STD_VER >= 17
+static_assert( std::is_constructible<std::shared_ptr<int[]>,  int*>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,  int(*)[]>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<int[5]>, int*>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>, int(*)[5]>::value, "");
+#endif
+
+// Test explicit
+static_assert(std::is_constructible<std::shared_ptr<int>, int*>::value, "");
+static_assert(!std::is_convertible<int*, std::shared_ptr<int> >::value, "");
+
 int main(int, char**)
 {
     {
         assert(A::count == 0);
         A* ptr = new A;
         std::shared_ptr<A> p(ptr);
         assert(A::count == 1);
         assert(p.use_count() == 1);
#if TEST_STD_VER > 14
     {
         assert(A::count == 0);
         std::shared_ptr<A[]> pA(new A[8]);
         assert(pA.use_count() == 1);
         assert(A::count == 8);
     }
 
     {
-          assert(A::count == 0);
         std::shared_ptr<const A[]> pA(new A[8]);
         assert(pA.use_count() == 1);
         assert(A::count == 8);
     }
+
+    {
+        assert(A::count == 0);
+        std::shared_ptr<A> pA(new Derived);
+        assert(pA.use_count() == 1);
+        assert(A::count == 1);
+    }
 #endif
 
     return 0;
 }

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/pointer_deleter.pass.cpp

 public:
     MoveDeleter(MoveDeleter&&) {};
 
     explicit MoveDeleter(int) {}
 
     void operator()(T *ptr) { delete ptr; }
 };
 
+// https://llvm.org/PR60258
+// Invalid constructor SFINAE for std::shared_ptr's array ctors
+static_assert( std::is_constructible<std::shared_ptr<int>,  int*, test_deleter<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int>,  int*, bad_deleter>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<Base>,  Derived*, test_deleter<Base> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<A>,  int*, test_deleter<A> >::value, "");
+
+#if TEST_STD_VER >= 17
+static_assert( std::is_constructible<std::shared_ptr<int[]>,  int*, test_deleter<int>>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,  int*, bad_deleter>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,  int(*)[], test_deleter<int>>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<int[5]>, int*, test_deleter<int>>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>, int*, bad_deleter>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>, int(*)[5], test_deleter<int>>::value, "");
+#endif
+
 int main(int, char**)
 {
     {
         A* ptr = new A;
         std::shared_ptr<A> p(ptr, test_deleter<A>(3));
         assert(A::count == 1);
         assert(p.use_count() == 1);
         assert(p.get() == ptr);

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/pointer_deleter_allocator.pass.cpp

 public:
     MoveDeleter(MoveDeleter&&) {};
 
     explicit MoveDeleter(int) {}
 
     void operator()(T *ptr) { delete ptr; }
 };
 
+// https://llvm.org/PR60258
+// Invalid constructor SFINAE for std::shared_ptr's array ctors
+static_assert( std::is_constructible<std::shared_ptr<int>,  int*, test_deleter<int>, test_allocator<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int>,  int*, bad_deleter, test_allocator<int> >::value, "");
+static_assert( std::is_constructible<std::shared_ptr<Base>,  Derived*, test_deleter<Base>, test_allocator<Base> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<A>,  int*, test_deleter<A>, test_allocator<A> >::value, "");
+
+#if TEST_STD_VER >= 17
+static_assert( std::is_constructible<std::shared_ptr<int[]>,  int*, test_deleter<int>, test_allocator<int>>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,  int*, bad_deleter, test_allocator<int>>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,  int(*)[], test_deleter<int>, test_allocator<int>>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<int[5]>, int*, test_deleter<int>, test_allocator<int>>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>, int*, bad_deleter, test_allocator<int>>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>, int(*)[5], test_deleter<int>, test_allocator<int>>::value, "");
+#endif
+
+
 int main(int, char**)
 {
     {
         test_allocator_statistics alloc_stats;
         {
             A* ptr = new A;
             std::shared_ptr<A> p(ptr, test_deleter<A>(3), test_allocator<A>(5, &alloc_stats));
             assert(A::count == 1);

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/shared_ptr_Y.pass.cpp

static void operator delete[] (void *p) {
         return delete[] static_cast<char*>(p);
     }
 public:
     static void operator delete (void *p) {
         return delete static_cast<char*>(p);
     }
 };
 
+// https://llvm.org/PR60258
+// Invalid constructor SFINAE for std::shared_ptr's array ctors
+static_assert(!std::is_constructible<std::shared_ptr<int>,     const std::shared_ptr<long>&>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<B>,       const std::shared_ptr<A>&>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<const A>, const std::shared_ptr<A>&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<A>,       const std::shared_ptr<const A>&>::value, "");
+
+#if TEST_STD_VER >= 17
+static_assert(!std::is_constructible<std::shared_ptr<int>,     const std::shared_ptr<int[]>&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int>,     const std::shared_ptr<int[5]>&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,   const std::shared_ptr<int>&>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<int[]>,   const std::shared_ptr<int[5]>&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>,  const std::shared_ptr<int>&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>,  const std::shared_ptr<int[]>&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[7]>,  const std::shared_ptr<int[5]>&>::value, "");
+#endif
+
 int main(int, char**)
 {
     static_assert(( std::is_convertible<std::shared_ptr<A>, std::shared_ptr<B> >::value), "");
     static_assert((!std::is_convertible<std::shared_ptr<B>, std::shared_ptr<A> >::value), "");
     static_assert((!std::is_convertible<std::shared_ptr<A>, std::shared_ptr<C> >::value), "");
     {
         const std::shared_ptr<A> pA(new A);
         assert(pA.use_count() == 1);

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/shared_ptr_Y_rv.pass.cpp

struct C
 
     C() {++count;}
     C(const C&) {++count;}
     virtual ~C() {--count;}
 };
 
 int C::count = 0;
 
+// https://llvm.org/PR60258
+// Invalid constructor SFINAE for std::shared_ptr's array ctors
+static_assert(!std::is_constructible<std::shared_ptr<int>,     std::shared_ptr<long>&&>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<B>,       std::shared_ptr<A>&&>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<const A>, std::shared_ptr<A>&&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<A>,       std::shared_ptr<const A>&&>::value, "");
+
+#if TEST_STD_VER >= 17
+static_assert(!std::is_constructible<std::shared_ptr<int>,     std::shared_ptr<int[]>&&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int>,     std::shared_ptr<int[5]>&&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,   std::shared_ptr<int>&&>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<int[]>,   std::shared_ptr<int[5]>&&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>,  std::shared_ptr<int>&&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>,  std::shared_ptr<int[]>&&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[7]>,  std::shared_ptr<int[5]>&&>::value, "");
+#endif
+
 int main(int, char**)
 {
     static_assert(( std::is_convertible<std::shared_ptr<A>, std::shared_ptr<B> >::value), "");
     static_assert((!std::is_convertible<std::shared_ptr<B>, std::shared_ptr<A> >::value), "");
     static_assert((!std::is_convertible<std::shared_ptr<A>, std::shared_ptr<C> >::value), "");
     {
         std::shared_ptr<A> pA(new A);
         assert(pA.use_count() == 1);

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/unique_ptr.pass.cpp

 
 struct MovingDeleter {
   explicit MovingDeleter(int *moves) : moves_(moves) {}
   MovingDeleter(MovingDeleter&& rhs) : moves_(rhs.moves_) { *moves_ += 1; }
   void operator()(int*) const {}
   int *moves_;
 };
 
+// https://llvm.org/PR53368
+// Bogus unique_ptr-to-shared_ptr conversions should be forbidden
+#if TEST_STD_VER >= 17
+static_assert( std::is_constructible<std::shared_ptr<A>,   std::unique_ptr<A>&&>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<A[]>, std::unique_ptr<A[]>&&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<A>,   std::unique_ptr<A[]>&&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<B[]>, std::unique_ptr<A[]>&&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<B>,   std::unique_ptr<A[]>&&>::value, "");
+#endif
+
 int main(int, char**)
 {
     {
         std::unique_ptr<A> ptr(new A);
         A* raw_ptr = ptr.get();
         std::shared_ptr<B> p(std::move(ptr));
         assert(A::count == 1);
         assert(B::count == 1);
#endif
 
     {
     adl::D d;
     std::unique_ptr<int, adl::D&> u(nullptr, d);
     std::shared_ptr<int> s = std::move(u);
     }
 
     assert(A::count == 0);
-#ifdef _LIBCPP_VERSION // https://llvm.org/PR53368
-    {
-      std::unique_ptr<A[]> ptr(new A[8]);
-      A* raw_ptr = ptr.get();
-      std::shared_ptr<B> p(std::move(ptr));
-      assert(A::count == 8);
-      assert(B::count == 8);
-      assert(p.use_count() == 1);
-      assert(p.get() == raw_ptr);
-      assert(ptr.get() == 0);
-    }
-    assert(A::count == 0);
-    assert(B::count == 0);
-
-    {
-      std::unique_ptr<A[]> ptr(new A[8]);
-      A* raw_ptr = ptr.get();
-      std::shared_ptr<A> p(std::move(ptr));
-      assert(A::count == 8);
-      assert(p.use_count() == 1);
-      assert(p.get() == raw_ptr);
-      assert(ptr.get() == 0);
-    }
-    assert(A::count == 0);
-
-    {
-      std::unique_ptr<int[]> ptr(new int[8]);
-      std::shared_ptr<int> p(std::move(ptr));
-    }
-#endif // _LIBCPP_VERSION
 
 #if TEST_STD_VER > 14
     {
       StatefulArrayDeleter<A> d;
       std::unique_ptr<A[], StatefulArrayDeleter<A>&> u(new A[4], d);
       std::shared_ptr<A[]> p(std::move(u));
       d.state = 42;
       assert(A::count == 4);
     }
     assert(A::count == 0);
     assert(B::count == 0);
 
-#ifdef _LIBCPP_VERSION // https://llvm.org/PR53368
-    {
-      std::unique_ptr<A[]> ptr(new A[8]);
-      A* raw_ptr = ptr.get();
-      std::shared_ptr<B[]> p(std::move(ptr));
-      assert(A::count == 8);
-      assert(B::count == 8);
-      assert(p.use_count() == 1);
-      assert(p.get() == raw_ptr);
-      assert(ptr.get() == 0);
-    }
-    assert(A::count == 0);
-    assert(B::count == 0);
-#endif // _LIBCPP_VERSION
-
     {
       std::unique_ptr<A[]> ptr(new A[8]);
       A* raw_ptr = ptr.get();
       std::shared_ptr<A[]> p(std::move(ptr));
       assert(A::count == 8);
       assert(p.use_count() == 1);
       assert(p.get() == raw_ptr);
       assert(ptr.get() == 0);

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/weak_ptr.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // <memory>
 
 // shared_ptr
 
 // template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
 
-#include <memory>
 #include <cassert>
+#include <memory>
+#include <type_traits>
 
 #include "test_macros.h"
 
 struct B
 {
     static int count;
 
     B() {++count;}
struct A
 
     A() {++count;}
     A(const A& other) : B(other) {++count;}
     ~A() {--count;}
 };
 
 int A::count = 0;
 
+// https://llvm.org/PR60258
+// Invalid constructor SFINAE for std::shared_ptr's array ctors
+static_assert(!std::is_constructible<std::shared_ptr<int>,     const std::weak_ptr<long>&>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<B>,       const std::weak_ptr<A>&>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<const A>, const std::weak_ptr<A>&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<A>,       const std::weak_ptr<const A>&>::value, "");
+
+#if TEST_STD_VER >= 17
+static_assert(!std::is_constructible<std::shared_ptr<int>,     const std::weak_ptr<int[]>&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int>,     const std::weak_ptr<int[5]>&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,   const std::weak_ptr<int>&>::value, "");
+static_assert( std::is_constructible<std::shared_ptr<int[]>,   const std::weak_ptr<int[5]>&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>,  const std::weak_ptr<int>&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>,  const std::weak_ptr<int[]>&>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[7]>,  const std::weak_ptr<int[5]>&>::value, "");
+#endif
+
 int main(int, char**)
 {
 #ifndef TEST_HAS_NO_EXCEPTIONS
     {
         std::weak_ptr<A> wp;
         try
         {
             std::shared_ptr<A> sp(wp);

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.mod/reset_helper.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+#ifndef TEST_STD_SHARED_PTR_RESET_H
+#define TEST_STD_SHARED_PTR_RESET_H
+
+#include <memory>
+#include <type_traits>
+
+template <class T, class... Args>
+std::false_type test_has_reset(...);
+
+template <class T, class... Args>
+typename std::enable_if<std::is_same<decltype(std::declval<T>().reset(std::declval<Args>()...)), void>::value,
+                        std::true_type>::type
+test_has_reset(int);
+
+template <class T, class... Args>
+using HasReset = decltype(test_has_reset<T, Args...>(0));
+
+#endif // TEST_STD_SHARED_PTR_RESET_H

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.mod/reset_pointer.pass.cpp

 
 // shared_ptr
 
 // template<class Y> void reset(Y* p);
 
 #include <memory>
 #include <cassert>
 
+#include "reset_helper.h"
 #include "test_macros.h"
 
 struct B
 {
     static int count;
 
     B() {++count;}
     B(const B&) {++count;}
struct A
 
     A() {++count;}
     A(const A& other) : B(other) {++count;}
     ~A() {--count;}
 };
 
 int A::count = 0;
 
+struct Derived : A {};
+
+static_assert( HasReset<std::shared_ptr<int>,  int*>::value, "");
+static_assert( HasReset<std::shared_ptr<A>,  Derived*>::value, "");
+static_assert(!HasReset<std::shared_ptr<A>,  int*>::value, "");
+
+#if TEST_STD_VER >= 17
+static_assert( HasReset<std::shared_ptr<int[]>,  int*>::value, "");
+static_assert(!HasReset<std::shared_ptr<int[]>,  int(*)[]>::value, "");
+static_assert( HasReset<std::shared_ptr<int[5]>, int*>::value, "");
+static_assert(!HasReset<std::shared_ptr<int[5]>, int(*)[5]>::value, "");
+#endif
+
 int main(int, char**)
 {
     {
         std::shared_ptr<B> p(new B);
         A* ptr = new A;
         p.reset(ptr);
         assert(A::count == 1);
         assert(B::count == 1);

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.mod/reset_pointer_deleter.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // <memory>
 
 // shared_ptr
 
 // template<class Y, class D> void reset(Y* p, D d);
 
-#include <memory>
 #include <cassert>
-#include "test_macros.h"
+#include <memory>
 #include "deleter_types.h"
+#include "reset_helper.h"
+#include "test_macros.h"
 
 struct B
 {
     static int count;
 
     B() {++count;}
     B(const B&) {++count;}
     virtual ~B() {--count;}
 };
 
 int B::count = 0;
 
 struct A
     : public B
 {
     static int count;
 
     A() {++count;}
     A(const A& other) : B(other) {++count;}
     ~A() {--count;}
 };
 
 int A::count = 0;
 
+struct bad_ty { };
+struct bad_deleter
+{
+    void operator()(bad_ty) { }
+};
+
+struct Base { };
+struct Derived : Base { };
+
+static_assert( HasReset<std::shared_ptr<int>,  int*, test_deleter<int> >::value, "");
+static_assert(!HasReset<std::shared_ptr<int>,  int*, bad_deleter>::value, "");
+static_assert( HasReset<std::shared_ptr<Base>,  Derived*, test_deleter<Base> >::value, "");
+static_assert(!HasReset<std::shared_ptr<A>,  int*, test_deleter<A> >::value, "");
+
+#if TEST_STD_VER >= 17
+static_assert( HasReset<std::shared_ptr<int[]>,  int*, test_deleter<int>>::value, "");
+static_assert(!HasReset<std::shared_ptr<int[]>,  int*, bad_deleter>::value, "");
+static_assert(!HasReset<std::shared_ptr<int[]>,  int(*)[], test_deleter<int>>::value, "");
+static_assert( HasReset<std::shared_ptr<int[5]>, int*, test_deleter<int>>::value, "");
+static_assert(!HasReset<std::shared_ptr<int[5]>, int*, bad_deleter>::value, "");
+static_assert(!HasReset<std::shared_ptr<int[5]>, int(*)[5], test_deleter<int>>::value, "");
+#endif
+
 int main(int, char**)
 {
     {
         std::shared_ptr<B> p(new B);
         A* ptr = new A;
         p.reset(ptr, test_deleter<A>(3));
         assert(A::count == 1);
         assert(B::count == 1);

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.mod/reset_pointer_deleter_allocator.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // <memory>
 
 // shared_ptr
 
 // template<class Y, class D, class A> void reset(Y* p, D d, A a);
 
-#include <memory>
 #include <cassert>
+#include <memory>
 #include "test_macros.h"
 #include "deleter_types.h"
+#include "reset_helper.h"
 #include "test_allocator.h"
 
 struct B
 {
     static int count;
 
     B() {++count;}
     B(const B&) {++count;}
struct A
 
     A() {++count;}
     A(const A& other) : B(other) {++count;}
     ~A() {--count;}
 };
 
 int A::count = 0;
 
+struct bad_ty { };
+
+struct bad_deleter
+{
+    void operator()(bad_ty) { }
+};
+
+struct Base { };
+struct Derived : Base { };
+
+static_assert( HasReset<std::shared_ptr<int>,  int*, test_deleter<int>, test_allocator<int> >::value, "");
+static_assert(!HasReset<std::shared_ptr<int>,  int*, bad_deleter, test_allocator<int> >::value, "");
+static_assert( HasReset<std::shared_ptr<Base>,  Derived*, test_deleter<Base>, test_allocator<Base> >::value, "");
+static_assert(!HasReset<std::shared_ptr<A>,  int*, test_deleter<A>, test_allocator<A> >::value, "");
+
+#if TEST_STD_VER >= 17
+static_assert( HasReset<std::shared_ptr<int[]>,  int*, test_deleter<int>, test_allocator<int>>::value, "");
+static_assert(!HasReset<std::shared_ptr<int[]>,  int*, bad_deleter, test_allocator<int>>::value, "");
+static_assert(!HasReset<std::shared_ptr<int[]>,  int(*)[], test_deleter<int>, test_allocator<int>>::value, "");
+static_assert( HasReset<std::shared_ptr<int[5]>, int*, test_deleter<int>, test_allocator<int>>::value, "");
+static_assert(!HasReset<std::shared_ptr<int[5]>, int*, bad_deleter, test_allocator<int>>::value, "");
+static_assert(!HasReset<std::shared_ptr<int[5]>, int(*)[5], test_deleter<int>, test_allocator<int>>::value, "");
+#endif
+
 int main(int, char**)
 {
     test_allocator_statistics alloc_stats;
     {
         std::shared_ptr<B> p(new B);
         A* ptr = new A;
         p.reset(ptr, test_deleter<A>(3), test_allocator<A>(4, &alloc_stats));
         assert(A::count == 1);