chore: import upstream snapshot with attribution

test/cpp/compat/c10_ptr_test.cc

@@ -0,0 +1,116 @@
+// Copyright (c) 2025 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <ATen/Functions.h>
+#include <ATen/core/TensorBody.h>
+#include <ATen/cuda/EmptyTensor.h>
+#include <ATen/native/cuda/Resize.h>
+#include <ATen/ops/tensor.h>
+#include <c10/core/Layout.h>
+#include <c10/core/ScalarType.h>
+#include <c10/core/SymInt.h>
+#include <c10/core/TensorOptions.h>
+#if defined(PADDLE_WITH_CUDA) || defined(PADDLE_WITH_HIP)
+#include <c10/cuda/CUDAFunctions.h>
+#include <c10/cuda/CUDAGuard.h>
+#endif
+#include "ATen/ATen.h"
+#include "gtest/gtest.h"
+#include "paddle/phi/common/float16.h"
+#include "torch/all.h"
+
+TEST(TensorBaseTest, IsSameAPI) {
+  // Test is_same() API - checks if two tensors share the same underlying data
+  at::Tensor tensor1 = at::ones({2, 3}, at::kFloat);
+  at::TensorBase tensor2 = tensor1;                       // Same tensor
+  at::TensorBase tensor3 = at::ones({2, 3}, at::kFloat);  // Different tensor
+
+  // tensor1 and tensor2 should point to the same underlying tensor
+  ASSERT_TRUE(tensor1.is_same(tensor2));
+  ASSERT_TRUE(tensor2.is_same(tensor1));
+
+  // tensor1 and tensor3 should be different tensors
+  ASSERT_FALSE(tensor1.is_same(tensor3));
+  ASSERT_FALSE(tensor3.is_same(tensor1));
+
+  // A tensor should be the same as itself
+  ASSERT_TRUE(tensor1.is_same(tensor1));
+
+  // Test with view - in Paddle, view creates a new tensor implementation
+  // even though they may share underlying data storage
+  at::TensorBase view_tensor = tensor1.view({6});
+  // View tensor has different impl pointer in Paddle
+  ASSERT_FALSE(tensor1.is_same(view_tensor));
+
+  // Test with undefined tensors
+  at::TensorBase undefined1;
+  at::TensorBase undefined2;
+  ASSERT_TRUE(undefined1.is_same(undefined2));  // Both undefined
+}
+
+TEST(TensorBaseTest, UseCountAPI) {
+  // Test use_count() API - returns reference count of underlying tensor
+  at::Tensor tensor1 = at::ones({2, 3}, at::kFloat);
+
+  // Initial reference count should be 1
+  ASSERT_EQ(tensor1.use_count(), 1);
+
+  // Create a copy - reference count should increase
+  at::TensorBase tensor2 = tensor1;
+  ASSERT_EQ(tensor1.use_count(), 2);
+  ASSERT_EQ(tensor2.use_count(), 2);
+
+  // Create another copy
+  at::TensorBase tensor3 = tensor1;
+  ASSERT_EQ(tensor1.use_count(), 3);
+  ASSERT_EQ(tensor2.use_count(), 3);
+  ASSERT_EQ(tensor3.use_count(), 3);
+
+  // Reset one copy - reference count should decrease
+  tensor2.reset();
+  ASSERT_EQ(tensor1.use_count(), 2);
+  ASSERT_EQ(tensor3.use_count(), 2);
+
+  // Reset another copy
+  tensor3.reset();
+  ASSERT_EQ(tensor1.use_count(), 1);
+
+  // Test with view - in Paddle, view creates a new tensor with separate impl
+  // So the use_count remains 1 for each
+  {
+    at::TensorBase view_tensor = tensor1.view({6});
+    // Each tensor has its own impl, so use_count is 1 for each
+    ASSERT_EQ(tensor1.use_count(), 1);
+    ASSERT_EQ(view_tensor.use_count(), 1);
+  }
+  // After view goes out of scope
+  ASSERT_EQ(tensor1.use_count(), 1);
+}
+
+TEST(TensorBaseTest, WeakUseCountAPI) {
+  // Test weak_use_count() API
+  // Compat exposes PyTorch-visible semantics: live TensorImpl wrappers report
+  // the self weak-reference count as 1.
+  at::TensorBase tensor1 = at::ones({2, 3}, at::kFloat);
+
+  ASSERT_EQ(tensor1.weak_use_count(), 1);
+
+  at::TensorBase tensor2 = tensor1;
+  ASSERT_EQ(tensor1.weak_use_count(), 1);
+  ASSERT_EQ(tensor2.weak_use_count(), 1);
+
+  // Test with undefined tensor
+  at::TensorBase undefined_tensor;
+  ASSERT_EQ(undefined_tensor.weak_use_count(), 0);
+}