[libc++] LWG3223 Broken requirements for shared_ptr converting constructors (#93071)

libcxx/docs/Status/Cxx20Issues.csv

@@ -200,7 +200,7 @@
 "`3200 <https://wg21.link/LWG3200>`__","``midpoint``\  should not constrain ``T``\  is complete","Prague","|Nothing To Do|",""
 "`3201 <https://wg21.link/LWG3201>`__","``lerp``\  should be marked as ``noexcept``\ ","Prague","|Complete|",""
 "`3226 <https://wg21.link/LWG3226>`__","``zoned_time``\  constructor from ``string_view``\  should accept ``zoned_time<Duration2, TimeZonePtr2>``\ ","Prague","","","|chrono|"
-"`3233 <https://wg21.link/LWG3233>`__","Broken requirements for ``shared_ptr``\  converting constructors","Prague","",""
+"`3233 <https://wg21.link/LWG3233>`__","Broken requirements for ``shared_ptr``\  converting constructors","Prague","|Complete|","19.0"
 "`3237 <https://wg21.link/LWG3237>`__","LWG 3038 and 3190 have inconsistent PRs","Prague","|Complete|","16.0"
 "`3238 <https://wg21.link/LWG3238>`__","Insufficiently-defined behavior of ``std::function``\  deduction guides","Prague","",""
 "`3242 <https://wg21.link/LWG3242>`__","``std::format``\ : missing rules for ``arg-id``\  in ``width``\  and ``precision``\ ","Prague","|Complete|","14.0","|format|"

libcxx/include/__memory/shared_ptr.h

@@ -403,6 +403,9 @@ struct __shared_ptr_deleter_ctor_reqs {
                             __well_formed_deleter<_Dp, _Yp*>::value;
 };
 
+template <class _Dp, class _Tp>
+using __shared_ptr_nullptr_deleter_ctor_reqs = _And<is_move_constructible<_Dp>, __well_formed_deleter<_Dp, nullptr_t> >;
+
 #if defined(_LIBCPP_ABI_ENABLE_SHARED_PTR_TRIVIAL_ABI)
 #  define _LIBCPP_SHARED_PTR_TRIVIAL_ABI __attribute__((__trivial_abi__))
 #else
@@ -498,7 +501,7 @@ public:
 #endif // _LIBCPP_HAS_NO_EXCEPTIONS
   }
 
-  template <class _Dp>
+  template <class _Dp, __enable_if_t<__shared_ptr_nullptr_deleter_ctor_reqs<_Dp, _Tp>::value, int> = 0 >
   _LIBCPP_HIDE_FROM_ABI shared_ptr(nullptr_t __p, _Dp __d) : __ptr_(nullptr) {
 #ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
@@ -518,7 +521,7 @@ public:
 #endif // _LIBCPP_HAS_NO_EXCEPTIONS
   }
 
-  template <class _Dp, class _Alloc>
+  template <class _Dp, class _Alloc, __enable_if_t<__shared_ptr_nullptr_deleter_ctor_reqs<_Dp, _Tp>::value, int> = 0 >
   _LIBCPP_HIDE_FROM_ABI shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a) : __ptr_(nullptr) {
 #ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {

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

@@ -17,6 +17,7 @@
 #include "test_macros.h"
 #include "deleter_types.h"
 
+#include "types.h"
 struct A
 {
     static int count;
@@ -28,6 +29,25 @@ struct A
 
 int A::count = 0;
 
+// LWG 3233. Broken requirements for shared_ptr converting constructors
+// https://cplusplus.github.io/LWG/issue3233
+static_assert( std::is_constructible<std::shared_ptr<int>,  std::nullptr_t, test_deleter<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int>,  std::nullptr_t, bad_deleter>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int>,  std::nullptr_t, no_nullptr_deleter>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int>,  std::nullptr_t, no_move_deleter>::value, "");
+
+#if TEST_STD_VER >= 17
+static_assert( std::is_constructible<std::shared_ptr<int[]>,  std::nullptr_t, test_deleter<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,  std::nullptr_t, bad_deleter>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,  std::nullptr_t, no_nullptr_deleter>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,  std::nullptr_t, no_move_deleter>::value, "");
+
+static_assert( std::is_constructible<std::shared_ptr<int[5]>,  std::nullptr_t, test_deleter<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>,  std::nullptr_t, bad_deleter>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>,  std::nullptr_t, no_nullptr_deleter>::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>,  std::nullptr_t, no_move_deleter>::value, "");
+#endif
+
 int main(int, char**)
 {
     {

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

@@ -17,6 +17,8 @@
 #include "test_allocator.h"
 #include "min_allocator.h"
 
+#include "types.h"
+
 struct A
 {
     static int count;
@@ -28,6 +30,25 @@ struct A
 
 int A::count = 0;
 
+// LWG 3233. Broken requirements for shared_ptr converting constructors
+// https://cplusplus.github.io/LWG/issue3233
+static_assert( std::is_constructible<std::shared_ptr<int>,  std::nullptr_t, test_deleter<int>, test_allocator<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int>,  std::nullptr_t, bad_deleter, test_allocator<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int>,  std::nullptr_t, no_nullptr_deleter, test_allocator<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int>,  std::nullptr_t, no_move_deleter, test_allocator<int> >::value, "");
+
+#if TEST_STD_VER >= 17
+static_assert( std::is_constructible<std::shared_ptr<int[]>,  std::nullptr_t, test_deleter<int>, test_allocator<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,  std::nullptr_t, bad_deleter, test_allocator<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,  std::nullptr_t, no_nullptr_deleter, test_allocator<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[]>,  std::nullptr_t, no_move_deleter, test_allocator<int> >::value, "");
+
+static_assert( std::is_constructible<std::shared_ptr<int[5]>,  std::nullptr_t, test_deleter<int>, test_allocator<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>,  std::nullptr_t, bad_deleter, test_allocator<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>,  std::nullptr_t, no_nullptr_deleter, test_allocator<int> >::value, "");
+static_assert(!std::is_constructible<std::shared_ptr<int[5]>,  std::nullptr_t, no_move_deleter, test_allocator<int> >::value, "");
+#endif
+
 int main(int, char**)
 {
     test_allocator_statistics alloc_stats;

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

@@ -17,6 +17,8 @@
 #include "test_macros.h"
 #include "deleter_types.h"
 
+#include "types.h"
+
 struct A
 {
     static int count;
@@ -28,38 +30,8 @@ struct A
 
 int A::count = 0;
 
-struct bad_ty { };
-
-struct bad_deleter
-{
-    void operator()(bad_ty) { }
-};
-
-struct no_move_deleter
-{
-    no_move_deleter(no_move_deleter const&) = delete;
-    no_move_deleter(no_move_deleter &&) = delete;
-    void operator()(int*) { }
-};
-
-static_assert(!std::is_move_constructible<no_move_deleter>::value, "");
-
-struct Base { };
-struct Derived : Base { };
-
-template<class T>
-class MoveDeleter
-{
-    MoveDeleter();
-    MoveDeleter(MoveDeleter const&);
-public:
-  MoveDeleter(MoveDeleter&&) {}
-
-  explicit MoveDeleter(int) {}
-
-  void operator()(T* ptr) { delete ptr; }
-};
-
+// LWG 3233. Broken requirements for shared_ptr converting constructors
+// https://cplusplus.github.io/LWG/issue3233
 // 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, "");

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

@@ -17,6 +17,7 @@
 #include "test_allocator.h"
 #include "min_allocator.h"
 
+#include "types.h"
 struct A
 {
     static int count;
@@ -28,38 +29,8 @@ struct A
 
 int A::count = 0;
 
-struct bad_ty { };
-
-struct bad_deleter
-{
-    void operator()(bad_ty) { }
-};
-
-struct no_move_deleter
-{
-    no_move_deleter(no_move_deleter const&) = delete;
-    no_move_deleter(no_move_deleter &&) = delete;
-    void operator()(int*) { }
-};
-
-static_assert(!std::is_move_constructible<no_move_deleter>::value, "");
-
-struct Base { };
-struct Derived : Base { };
-
-template<class T>
-class MoveDeleter
-{
-    MoveDeleter();
-    MoveDeleter(MoveDeleter const&);
-public:
-  MoveDeleter(MoveDeleter&&) {}
-
-  explicit MoveDeleter(int) {}
-
-  void operator()(T* ptr) { delete ptr; }
-};
-
+// LWG 3233. Broken requirements for shared_ptr converting constructors
+// https://cplusplus.github.io/LWG/issue3233
 // 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, "");

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/types.h

@@ -0,0 +1,49 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_UTILITIES_MEMORY_UTIL_SMARTPTR_SHARED_CONST_TYPES_H
+#define TEST_STD_UTILITIES_MEMORY_UTIL_SMARTPTR_SHARED_CONST_TYPES_H
+
+#include <type_traits>
+
+struct bad_ty {};
+
+struct bad_deleter {
+  void operator()(bad_ty) {}
+};
+
+struct no_move_deleter {
+  no_move_deleter(no_move_deleter const&) = delete;
+  no_move_deleter(no_move_deleter&&)      = delete;
+  void operator()(int*) {}
+};
+
+static_assert(!std::is_move_constructible<no_move_deleter>::value, "");
+
+struct no_nullptr_deleter {
+  void operator()(int*) const {}
+  void operator()(std::nullptr_t) const = delete;
+};
+
+struct Base {};
+struct Derived : Base {};
+
+template <class T>
+class MoveDeleter {
+  MoveDeleter();
+  MoveDeleter(MoveDeleter const&);
+
+public:
+  MoveDeleter(MoveDeleter&&) {}
+
+  explicit MoveDeleter(int) {}
+
+  void operator()(T* ptr) { delete ptr; }
+};
+
+#endif // TEST_STD_UTILITIES_MEMORY_UTIL_SMARTPTR_SHARED_CONST_TYPES_H