[CUDAX] Add assignment operator that rebinds resource_ref

cudax/include/cuda/experimental/__memory_resource/any_resource.cuh

@@ -365,14 +365,38 @@ struct _CCCL_DECLSPEC_EMPTY_BASES synchronous_resource_ref
   template <class... _OtherProperties>
   synchronous_resource_ref(::cuda::mr::resource_ref<_OtherProperties...>) = delete;
 
+  _CCCL_TEMPLATE(class... _OtherProperties)
+  _CCCL_REQUIRES((::cuda::std::__type_set_contains_v<::cuda::std::__type_set<_OtherProperties...>, _Properties...>) )
+  synchronous_resource_ref& operator=(const synchronous_resource_ref<_OtherProperties...>& __other) noexcept
+  {
+    __basic_any_access::__cast_to(
+      const_cast<synchronous_resource_ref<_OtherProperties...>&>(__other).__get_base(), __get_base());
+    return *this;
+  }
+
+  synchronous_resource_ref& operator=(const synchronous_resource_ref& __other) noexcept
+  {
+    __basic_any_access::__cast_to(const_cast<synchronous_resource_ref&>(__other).__get_base(), __get_base());
+    return *this;
+  }
+
   using default_queries = ::cuda::mr::properties_list<_Properties...>;
 
 private:
   static_assert(::cuda::mr::__contains_execution_space_property<_Properties...>,
                 "The properties of cuda::experimental::synchronous_resource_ref must contain at least one execution "
                 "space "
                 "property!");
+
+  template <class...>
+  friend struct synchronous_resource_ref;
+
   using __base::interface;
+
+  __base& __get_base() noexcept
+  {
+    return *this;
+  }
 };
 
 //! @brief Type erased wrapper around a `synchronous_resource` that satisfies \tparam _Properties
@@ -389,6 +413,20 @@ struct _CCCL_DECLSPEC_EMPTY_BASES resource_ref
   // Inherit other constructors from __basic_any
   _LIBCUDACXX_DELEGATE_CONSTRUCTORS(resource_ref, ::cuda::__basic_any, experimental::__iasync_resource<_Properties...>&);
 
+  _CCCL_TEMPLATE(class... _OtherProperties)
+  _CCCL_REQUIRES((::cuda::std::__type_set_contains_v<::cuda::std::__type_set<_OtherProperties...>, _Properties...>) )
+  resource_ref& operator=(const resource_ref<_OtherProperties...>& __other) noexcept
+  {
+    __basic_any_access::__cast_to(const_cast<resource_ref<_OtherProperties...>&>(__other).__get_base(), __get_base());
+    return *this;
+  }
+
+  resource_ref& operator=(const resource_ref& __other) noexcept
+  {
+    __basic_any_access::__cast_to(const_cast<resource_ref&>(__other).__get_base(), __get_base());
+    return *this;
+  }
+
   using default_queries = ::cuda::mr::properties_list<_Properties...>;
 
 private:
@@ -398,6 +436,8 @@ private:
 
   template <class...>
   friend struct synchronous_resource_ref;
+  template <class...>
+  friend struct resource_ref;
 
   using __base::interface;
 

cudax/test/memory_resource/any_async_resource.cu

@@ -181,4 +181,24 @@ TEMPLATE_TEST_CASE_METHOD(test_fixture, "any_resource", "[container][resource]",
   this->counts = Counts();
 }
 
+TEMPLATE_TEST_CASE_METHOD(
+  test_fixture, "ref assignment operators", "[container][resource]", big_resource, small_resource)
+{
+  big_resource mr{42, this};
+  cudax::resource_ref<::cuda::mr::host_accessible, get_data> ref{mr};
+  CHECK(ref.allocate_sync(bytes(100), align(8)) == this);
+  CHECK(get_property(ref, get_data{}) == 42);
+
+  big_resource mr2{43, this};
+  cudax::resource_ref<::cuda::mr::host_accessible, get_data> ref2{mr2};
+  ref = ref2;
+  CHECK(ref.allocate_sync(bytes(100), align(8)) == this);
+  CHECK(get_property(ref, get_data{}) == 43);
+
+  cudax::resource_ref<::cuda::mr::host_accessible, get_data, extra_property> ref3{mr};
+  ref = ref3;
+  CHECK(ref.allocate_sync(bytes(100), align(8)) == this);
+  CHECK(get_property(ref, get_data{}) == 42);
+}
+
 #endif // __CUDA_ARCH__

cudax/test/memory_resource/any_resource.cu

@@ -287,3 +287,23 @@ TEMPLATE_TEST_CASE_METHOD(
   // Reset the counters:
   this->counts = Counts();
 }
+
+TEMPLATE_TEST_CASE_METHOD(
+  test_fixture, "synchronous ref assignment operators", "[container][resource]", big_resource, small_resource)
+{
+  big_resource mr{42, this};
+  cudax::synchronous_resource_ref<::cuda::mr::host_accessible, get_data> ref{mr};
+  CHECK(ref.allocate_sync(bytes(100), align(8)) == this);
+  CHECK(get_property(ref, get_data{}) == 42);
+
+  big_resource mr2{43, this};
+  cudax::synchronous_resource_ref<::cuda::mr::host_accessible, get_data> ref2{mr2};
+  ref = ref2;
+  CHECK(ref.allocate_sync(bytes(100), align(8)) == this);
+  CHECK(get_property(ref, get_data{}) == 43);
+
+  cudax::synchronous_resource_ref<::cuda::mr::host_accessible, get_data, extra_property> ref3{mr};
+  ref = ref3;
+  CHECK(ref.allocate_sync(bytes(100), align(8)) == this);
+  CHECK(get_property(ref, get_data{}) == 42);
+}

cudax/test/memory_resource/test_resource.cuh

@@ -96,6 +96,9 @@ struct get_data
   using value_type = int;
 };
 
+struct extra_property
+{};
+
 template <class T>
 struct test_resource
 {
@@ -213,6 +216,7 @@ struct test_resource
   }
 
   friend constexpr void get_property(const test_resource&, ::cuda::mr::host_accessible) noexcept {}
+  friend constexpr void get_property(const test_resource&, extra_property) noexcept {}
   friend constexpr int get_property(const test_resource& self, get_data) noexcept
   {
     return self.data;