Unify Array enumerators between CoreCLR and NativeAOT

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Array.NativeAot.cs

@@ -1157,38 +1157,6 @@ private static int LastIndexOfImpl<T>(T[] array, T value, int startIndex, int co
         }
     }
 
-    internal class ArrayEnumeratorBase : ICloneable
-    {
-        protected int _index;
-        protected int _endIndex;
-
-        internal ArrayEnumeratorBase()
-        {
-            _index = -1;
-        }
-
-        public bool MoveNext()
-        {
-            if (_index < _endIndex)
-            {
-                _index++;
-                return (_index < _endIndex);
-            }
-            return false;
-        }
-
-        public object Clone()
-        {
-            return MemberwiseClone();
-        }
-
-#pragma warning disable CA1822 // https://github.com/dotnet/roslyn-analyzers/issues/5911
-        public void Dispose()
-        {
-        }
-#pragma warning restore CA1822
-    }
-
     //
     // Note: the declared base type and interface list also determines what Reflection returns from TypeInfo.BaseType and TypeInfo.ImplementedInterfaces for array types.
     // This also means the class must be declared "public" so that the framework can reflect on it.
@@ -1200,17 +1168,15 @@ private Array() { }
 
         public new IEnumerator<T> GetEnumerator()
         {
-            // get length so we don't have to call the Length property again in ArrayEnumerator constructor
-            // and avoid more checking there too.
-            int length = this.Length;
-            return length == 0 ? ArrayEnumerator.Empty : new ArrayEnumerator(Unsafe.As<T[]>(this), length);
+            T[] @this = Unsafe.As<T[]>(this);
+            return @this.Length == 0 ? SZGenericArrayEnumerator<T>.Empty : new SZGenericArrayEnumerator<T>(@this);
         }
 
         public int Count
         {
             get
             {
-                return this.Length;
+                return Unsafe.As<T[]>(this).Length;
             }
         }
 
@@ -1240,13 +1206,14 @@ public void Clear()
 
         public bool Contains(T item)
         {
-            T[] array = Unsafe.As<T[]>(this);
-            return Array.IndexOf(array, item, 0, array.Length) >= 0;
+            T[] @this = Unsafe.As<T[]>(this);
+            return Array.IndexOf(@this, item, 0, @this.Length) >= 0;
         }
 
         public void CopyTo(T[] array, int arrayIndex)
         {
-            Array.Copy(Unsafe.As<T[]>(this), 0, array, arrayIndex, this.Length);
+            T[] @this = Unsafe.As<T[]>(this);
+            Array.Copy(@this, 0, array, arrayIndex, @this.Length);
         }
 
         public bool Remove(T item)
@@ -1284,8 +1251,8 @@ public T this[int index]
 
         public int IndexOf(T item)
         {
-            T[] array = Unsafe.As<T[]>(this);
-            return Array.IndexOf(array, item, 0, array.Length);
+            T[] @this = Unsafe.As<T[]>(this);
+            return Array.IndexOf(@this, item, 0, @this.Length);
         }
 
         public void Insert(int index, T item)
@@ -1297,43 +1264,6 @@ public void RemoveAt(int index)
         {
             ThrowHelper.ThrowNotSupportedException();
         }
-
-        private sealed class ArrayEnumerator : ArrayEnumeratorBase, IEnumerator<T>
-        {
-            private readonly T[] _array;
-
-            // Passing -1 for endIndex so that MoveNext always returns false without mutating _index
-            internal static readonly ArrayEnumerator Empty = new ArrayEnumerator(null, -1);
-
-            internal ArrayEnumerator(T[] array, int endIndex)
-            {
-                _array = array;
-                _endIndex = endIndex;
-            }
-
-            public T Current
-            {
-                get
-                {
-                    if ((uint)_index >= (uint)_endIndex)
-                        ThrowHelper.ThrowInvalidOperationException();
-                    return _array[_index];
-                }
-            }
-
-            object IEnumerator.Current
-            {
-                get
-                {
-                    return Current;
-                }
-            }
-
-            void IEnumerator.Reset()
-            {
-                _index = -1;
-            }
-        }
     }
 
     public class MDArray

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/DependencyAnalysis/NodeFactory.cs

@@ -1057,7 +1057,7 @@ public TypeDesc ArrayOfTEnumeratorType
         {
             get
             {
-                _systemArrayOfTEnumeratorType ??= _systemArrayOfTEnumeratorType = ArrayOfTClass.GetNestedType("ArrayEnumerator");
+                _systemArrayOfTEnumeratorType ??= _systemArrayOfTEnumeratorType = _context.SystemModule.GetKnownType("System", "SZGenericArrayEnumerator`1");
                 return _systemArrayOfTEnumeratorType;
             }
         }

src/libraries/System.Private.CoreLib/src/System/Array.Enumerators.cs

@@ -1,8 +1,10 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Runtime.CompilerServices;
 using System.Diagnostics;
 
 namespace System
@@ -26,9 +28,10 @@ public object Clone()
         public bool MoveNext()
         {
             nint index = _index + 1;
-            if ((nuint)index >= _array.NativeLength)
+            nuint length = _array.NativeLength;
+            if ((nuint)index >= length)
             {
-                _index = (nint)_array.NativeLength;
+                _index = (nint)length;
                 return false;
             }
             _index = index;
@@ -64,18 +67,12 @@ public void Reset()
         }
     }
 
-    internal sealed class SZGenericArrayEnumerator<T> : IEnumerator<T>
+    internal class SZGenericArrayEnumeratorBase
     {
-        private readonly T[] _array;
-        private int _index;
+        protected readonly Array _array;
+        protected int _index;
 
-        // Array.Empty is intentionally omitted here, since we don't want to pay for generic instantiations that
-        // wouldn't have otherwise been used.
-#pragma warning disable CA1825
-        internal static readonly SZGenericArrayEnumerator<T> Empty = new SZGenericArrayEnumerator<T>(new T[0]);
-#pragma warning restore CA1825
-
-        internal SZGenericArrayEnumerator(T[] array)
+        protected SZGenericArrayEnumeratorBase(Array array)
         {
             Debug.Assert(array != null);
 
@@ -86,21 +83,44 @@ internal SZGenericArrayEnumerator(T[] array)
         public bool MoveNext()
         {
             int index = _index + 1;
-            if ((uint)index >= (uint)_array.Length)
+            uint length = (uint)_array.NativeLength;
+            if ((uint)index >= length)
             {
-                _index = _array.Length;
+                _index = (int)length;
                 return false;
             }
             _index = index;
             return true;
         }
 
+        public void Reset() => _index = -1;
+
+#pragma warning disable CA1822 // Mark members as static
+        public void Dispose()
+        {
+        }
+#pragma warning restore CA1822
+    }
+
+    internal sealed class SZGenericArrayEnumerator<T> : SZGenericArrayEnumeratorBase, IEnumerator<T>
+    {
+        // Array.Empty is intentionally omitted here, since we don't want to pay for generic instantiations that
+        // wouldn't have otherwise been used.
+#pragma warning disable CA1825
+        internal static readonly SZGenericArrayEnumerator<T> Empty = new SZGenericArrayEnumerator<T>(new T[0]);
+#pragma warning restore CA1825
+
+        public SZGenericArrayEnumerator(T[] array)
+            : base(array)
+        {
+        }
+
         public T Current
         {
             get
             {
                 int index = _index;
-                T[] array = _array;
+                T[] array = Unsafe.As<T[]>(_array);
 
                 if ((uint)index >= (uint)array.Length)
                 {
@@ -112,11 +132,5 @@ public T Current
         }
 
         object? IEnumerator.Current => Current;
-
-        void IEnumerator.Reset() => _index = -1;
-
-        public void Dispose()
-        {
-        }
     }
 }