Revert "Revert "[libc++] Revert temporary attempt to implement LWG 4110 (#95263)""

This reverts commit 8bdab5c.

Author: huixie90

libcxx/docs/Status/Cxx2cIssues.csv

@@ -65,5 +65,4 @@
 "`3343 <https://wg21.link/LWG3343>`__","Ordering of calls to ``unlock()`` and ``notify_all()`` in Effects element of ``notify_all_at_thread_exit()`` should be reversed","Not Yet Adopted","|Complete|","16.0",""
 "XXXX","","The sys_info range should be affected by save","Not Yet Adopted","|Complete|","19.0"
 "`4071 <https://wg21.link/LWG4071>`__","","``reference_wrapper`` comparisons are not SFINAE-friendly","Not Yet Adopted","|Complete|","19.0"
-"`4110 <https://wg21.link/LWG4110>`__","","``shared_ptr(nullptr_t, Deleter)`` is overconstrained, breaking some sensible deleters","Not Yet Adopted","|Complete|","19.0"
 "","","","","",""

libcxx/include/__memory/shared_ptr.h

@@ -404,7 +404,7 @@ struct __shared_ptr_deleter_ctor_reqs {
 };
 
 template <class _Dp, class _Tp>
-using __shared_ptr_nullptr_deleter_ctor_reqs = _And<is_move_constructible<_Dp>, __well_formed_deleter<_Dp, _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__))

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

@@ -32,16 +32,17 @@ 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, 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, 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[5]> >::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, "");

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

@@ -33,21 +33,17 @@ 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, 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, 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[5]>, 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, "");

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

@@ -130,6 +130,6 @@ int main(int, char**)
     }
 #endif
 
-    test_function_type();
-    return 0;
+  test_function_type();
+  return 0;
 }

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

@@ -165,13 +165,5 @@ int main(int, char**)
                                              test_allocator<Derived[4]> >::value, "");
     }
 
-#if TEST_STD_VER >= 14
-    {
-      // LWG 4110
-      auto deleter = [](auto pointer) { delete pointer; };
-      std::shared_ptr<int> p(new int, deleter, std::allocator<int>());
-    }
-#endif
-
   return 0;
 }