Expose type-erased tensor from generic one. (pytorch#11962)

Author: shoumikhin

extension/apple/ExecuTorch/Exported/ExecuTorch+Tensor.swift

@@ -821,9 +821,8 @@ public class Tensor<T: Scalar>: Equatable {
     lhs.anyTensor == rhs.anyTensor
   }
 
-  // MARK: Internal
-
-  let anyTensor: AnyTensor
+  // Wrapped AnyTensor instance.
+  public let anyTensor: AnyTensor
 }
 
 @available(*, deprecated, message: "This API is experimental.")

extension/apple/ExecuTorch/__tests__/TensorTest.swift

@@ -678,6 +678,66 @@ class TensorTest: XCTestCase {
     XCTAssertEqual(try tensor.scalars().first, 42)
   }
 
+  func testExtractAnyTensorMatchesOriginalDataAndMetadata() {
+    let tensor = Tensor([1, 2, 3, 4], shape: [2, 2])
+    let anyTensor = tensor.anyTensor
+    XCTAssertEqual(anyTensor.shape, tensor.shape)
+    XCTAssertEqual(anyTensor.strides, tensor.strides)
+    XCTAssertEqual(anyTensor.dimensionOrder, tensor.dimensionOrder)
+    XCTAssertEqual(anyTensor.count, tensor.count)
+    XCTAssertEqual(anyTensor.dataType, tensor.dataType)
+    XCTAssertEqual(anyTensor.shapeDynamism, tensor.shapeDynamism)
+    let newTensor = Tensor<Int>(anyTensor)
+    XCTAssertEqual(newTensor, tensor)
+  }
+
+  func testReconstructGenericTensorViaInitAndAsTensor() {
+    let tensor = Tensor([5, 6, 7])
+    let anyTensor = tensor.anyTensor
+    let tensorInit = Tensor<Int>(anyTensor)
+    let tensorFromAny: Tensor<Int> = anyTensor.asTensor()!
+    XCTAssertEqual(tensorInit, tensorFromAny)
+  }
+
+  func testAsTensorMismatchedTypeReturnsNil() {
+    let tensor = Tensor([8, 9, 10])
+    let anyTensor = tensor.anyTensor
+    let wrongTypedTensor: Tensor<Float>? = anyTensor.asTensor()
+    XCTAssertNil(wrongTypedTensor)
+  }
+
+  func testViewSharesDataAndResizeAltersShapeNotData() throws {
+    var scalars = [11, 12, 13, 14]
+    let tensor = Tensor(&scalars, shape: [2, 2])
+    let viewTensor = Tensor(tensor)
+    let scalarsAddress = scalars.withUnsafeBufferPointer { $0.baseAddress }
+    let tensorDataAddress = try tensor.withUnsafeBytes { $0.baseAddress }
+    let viewTensorDataAddress = try viewTensor.withUnsafeBytes { $0.baseAddress }
+    XCTAssertEqual(tensorDataAddress, scalarsAddress)
+    XCTAssertEqual(tensorDataAddress, viewTensorDataAddress)
+
+    scalars[2] = 42
+    XCTAssertEqual(try tensor.scalars(), scalars)
+    XCTAssertEqual(try viewTensor.scalars(), scalars)
+
+    XCTAssertNoThrow(try viewTensor.resize(to: [4, 1]))
+    XCTAssertEqual(viewTensor.shape, [4, 1])
+    XCTAssertEqual(tensor.shape, [2, 2])
+    XCTAssertEqual(try tensor.scalars(), scalars)
+    XCTAssertEqual(try viewTensor.scalars(), scalars)
+  }
+
+  func testMultipleGenericFromAnyReflectChanges() {
+    let tensor = Tensor([2, 4, 6, 8], shape: [2, 2])
+    let anyTensor = tensor.anyTensor
+    let tensor1: Tensor<Int> = anyTensor.asTensor()!
+    let tensor2: Tensor<Int> = anyTensor.asTensor()!
+
+    XCTAssertEqual(tensor1, tensor2)
+    XCTAssertNoThrow(try tensor1.withUnsafeMutableBytes { $0[1] = 42 })
+    XCTAssertEqual(try tensor2.withUnsafeBytes { $0[1] }, 42)
+  }
+
   func testEmpty() {
     let tensor = Tensor<Float>.empty(shape: [3, 4])
     XCTAssertEqual(tensor.shape, [3, 4])