Remove deprecated 'Dataset` (#1115)

* Remove DatasetTests

* Remove Dataset.swift

* Move Zip2Tensor into LazyTensorExplicitTraceTests

Remove Zip2Tensor reference from LazyTensorTraceTests

Author: texasmichelle

Sources/TensorFlow/CMakeLists.txt

@@ -60,7 +60,6 @@ add_library(TensorFlow SHARED
 
   Operators/Basic.swift
   Operators/Comparison.swift
-  Operators/Dataset.swift
   Operators/Image.swift
   Operators/LinearAlgebra.swift
   Operators/Math.swift

Sources/TensorFlow/Operators/Dataset.swift

@@ -189,3 +189,43 @@ final class LazyTensorExplicitTraceTests: LazyTensorTestCase {
     ("testRetainsIdenticalOutputs", testRetainsIdenticalOutputs),
   ]
 }
+
+/// A 2-tuple-like struct that conforms to TensorGroup that represents a tuple of 2 types conforming
+/// to `TensorGroup`.
+fileprivate struct Zip2TensorGroup<T: TensorGroup, U: TensorGroup>: TensorGroup {
+  var first: T
+  var second: U
+
+  init(_ first: T, _ second: U) {
+    self.first = first
+    self.second = second
+  }
+
+  static var _typeList: [TensorDataType] { return T._typeList + U._typeList }
+
+  init(_owning tensorHandles: UnsafePointer<CTensorHandle>?) {
+    first = .init(_owning: tensorHandles)
+    second = .init(_owning: tensorHandles?.advanced(by: Int(T._tensorHandleCount)))
+  }
+
+  func _unpackTensorHandles(into address: UnsafeMutablePointer<CTensorHandle>?) {
+    var ptr = address
+    first._unpackTensorHandles(into: ptr)
+    ptr = ptr!.advanced(by: Int(first._tensorHandleCount))
+    second._unpackTensorHandles(into: ptr)
+  }
+
+  var _tensorHandles: [_AnyTensorHandle] {
+    first._tensorHandles + second._tensorHandles
+  }
+
+  init<C: RandomAccessCollection>(
+    _handles: C
+  ) where C.Element: _AnyTensorHandle {
+    let firstStart = _handles.startIndex
+    let firstEnd = _handles.index(
+      firstStart, offsetBy: Int(T._tensorHandleCount))
+    self.first = T.init(_handles: _handles[firstStart..<firstEnd])
+    self.second = U.init(_handles: _handles[firstEnd..<_handles.endIndex])
+  }
+}

Tests/TensorFlowTests/LazyTensorExplicitTraceTests.swift

@@ -204,7 +204,6 @@ final class LazyTensorTraceTests: LazyTensorTestCase {
   }
 
   func testTraceWithFunctionAttributes() {
-    typealias Int32Pair = Zip2TensorGroup<Tensor<Int32>, Tensor<Int32>>
     func thenBranch(x: Tensor<Float>) -> Tensor<Float> {
       return x + 10.0
     }