Add index to OrderedDictionary debugger display

src/libraries/Common/tests/System/Collections/DebugView.Tests.cs

@@ -166,6 +166,9 @@ private static IEnumerable<object[]> TestDebuggerAttributes_ListInputs()
             yield return new object[] { new SortedList<int, string>() };
             yield return new object[] { new SortedSet<int>() };
             yield return new object[] { new Stack<object>() };
+#if !NETFRAMEWORK
+            yield return new object[] { new OrderedDictionary<string, string>() };
+#endif
 
             yield return new object[] { new Dictionary<double, float>().Keys };
             yield return new object[] { new Dictionary<float, double>().Values };
@@ -193,6 +196,10 @@ private static IEnumerable<object[]> TestDebuggerAttributes_ListInputs()
             stack.Push(2);
             yield return new object[] { stack };
 
+#if !NETFRAMEWORK
+            yield return new object[] { new OrderedDictionary<string, string> { { "One", "1" }, { "Two", "2" } } };
+#endif
+
             yield return new object[] { new SortedList<string, int> { { "One", 1 }, { "Two", 2 } }.Keys };
             yield return new object[] { new SortedList<float, long> { { 1f, 1L }, { 2f, 2L } }.Values };
 
@@ -277,6 +284,33 @@ public static void TestDebuggerAttributes_Null(object obj)
             Assert.IsType<ArgumentNullException>(tie.InnerException);
         }
 
+#if !NETFRAMEWORK
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsDebuggerTypeProxyAttributeSupported))]
+        public static void TestDebuggerAttributes_OrderedDictionary()
+        {
+            // Validate that OrderedDictionary displays as a list of KeyValuePairs with implicit indexing
+            var dict = new OrderedDictionary<string, string> { { "One", "1" }, { "Two", "2" }, { "Three", "3" } };
+
+            DebuggerAttributes.ValidateDebuggerDisplayReferences(dict);
+            DebuggerAttributeInfo info = DebuggerAttributes.ValidateDebuggerTypeProxyProperties(dict);
+            PropertyInfo itemProperty = info.Properties.Single(pr => pr.GetCustomAttribute<DebuggerBrowsableAttribute>().State == DebuggerBrowsableState.RootHidden);
+
+            // The debug view should return a KeyValuePair array
+            var items = itemProperty.GetValue(info.Instance) as Array;
+            Assert.NotNull(items);
+            Assert.Equal(3, items.Length);
+
+            // Verify the items are KeyValuePairs in the correct order
+            var kvpArray = items.Cast<KeyValuePair<string, string>>().ToArray();
+            Assert.Equal("One", kvpArray[0].Key);
+            Assert.Equal("1", kvpArray[0].Value);
+            Assert.Equal("Two", kvpArray[1].Key);
+            Assert.Equal("2", kvpArray[1].Value);
+            Assert.Equal("Three", kvpArray[2].Key);
+            Assert.Equal("3", kvpArray[2].Value);
+        }
+#endif
+
         private class CustomKeyedCollection<TKey, TValue> : KeyedCollection<TKey, TValue> where TKey : notnull
         {
             public CustomKeyedCollection() : base()

src/libraries/System.Collections/src/System.Collections.csproj

@@ -17,6 +17,7 @@
     <Compile Include="$(CoreLibSharedDir)System\Collections\ObjectModel\CollectionHelpers.cs" Link="Common\System\Collections\ObjectModel\CollectionHelpers.cs" />
     <Compile Include="System\Collections\Generic\LinkedList.cs" />
     <Compile Include="System\Collections\Generic\OrderedDictionary.cs" />
+    <Compile Include="System\Collections\Generic\OrderedDictionaryDebugView.cs" />
     <Compile Include="System\Collections\Generic\PriorityQueue.cs" />
     <Compile Include="System\Collections\Generic\PriorityQueueDebugView.cs" />
     <Compile Include="System\Collections\Generic\SortedDictionary.cs" />

src/libraries/System.Collections/src/System/Collections/Generic/OrderedDictionary.cs

@@ -23,7 +23,7 @@ namespace System.Collections.Generic
     /// Operations on the collection have algorithmic complexities that are similar to that of the <see cref="List{T}"/>
     /// class, except with lookups by key similar in complexity to that of <see cref="Dictionary{TKey, TValue}"/>.
     /// </remarks>
-    [DebuggerTypeProxy(typeof(IDictionaryDebugView<,>))]
+    [DebuggerTypeProxy(typeof(OrderedDictionaryDebugView<,>))]
     [DebuggerDisplay("Count = {Count}")]
 #if SYSTEM_COLLECTIONS
     public

src/libraries/System.Collections/src/System/Collections/Generic/OrderedDictionaryDebugView.cs

@@ -0,0 +1,29 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Diagnostics;
+
+namespace System.Collections.Generic
+{
+    internal sealed class OrderedDictionaryDebugView<TKey, TValue> where TKey : notnull
+    {
+        private readonly OrderedDictionary<TKey, TValue> _dictionary;
+
+        public OrderedDictionaryDebugView(OrderedDictionary<TKey, TValue> dictionary)
+        {
+            ArgumentNullException.ThrowIfNull(dictionary);
+            _dictionary = dictionary;
+        }
+
+        [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
+        public KeyValuePair<TKey, TValue>[] Items
+        {
+            get
+            {
+                KeyValuePair<TKey, TValue>[] items = new KeyValuePair<TKey, TValue>[_dictionary.Count];
+                ((ICollection<KeyValuePair<TKey, TValue>>)_dictionary).CopyTo(items, 0);
+                return items;
+            }
+        }
+    }
+}

src/libraries/System.Text.Json/src/System.Text.Json.csproj

@@ -375,6 +375,7 @@ The System.Text.Json library is built-in as part of the shared framework in .NET
     <Compile Include="$(CoreLibSharedDir)System\Collections\ObjectModel\CollectionHelpers.cs" Link="Common\System\Collections\ObjectModel\CollectionHelpers.cs" />
     <Compile Include="$(CommonPath)System\Collections\Generic\EnumerableHelpers.cs" Link="Common\System\Collections\Generic\EnumerableHelpers.cs" />
     <Compile Include="$(LibrariesProjectRoot)System.Collections\src\System\Collections\Generic\OrderedDictionary.cs" Link="Common\System\Collections\Generic\OrderedDictionary.cs" />
+    <Compile Include="$(LibrariesProjectRoot)System.Collections\src\System\Collections\Generic\OrderedDictionaryDebugView.cs" Link="Common\System\Collections\Generic\OrderedDictionaryDebugView.cs" />
     <Compile Include="$(LibrariesProjectRoot)System.Collections\src\System\Collections\ThrowHelper.cs" Link="Common\System\Collections\ThrowHelper.cs" />
 
     <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\FeatureSwitchDefinitionAttribute.cs" />