Improve and unify debug views of dictionaries.

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

@@ -13,8 +13,8 @@
     <Compile Include="System\Collections\SortedList.cs" />
     <Compile Include="System\Collections\Stack.cs" />
     <Compile Include="System\Collections\Specialized\CollectionsUtil.cs" />
-    <Compile Include="$(CoreLibSharedDir)System\Collections\KeyValuePairs.cs"
-             Link="Common\System\Collections\KeyValuePairs.cs" />
+    <Compile Include="$(CoreLibSharedDir)System\Collections\Generic\DebugViewDictionaryItem.cs"
+             Link="Common\System\Collections\Generic\DebugViewDictionaryItem.cs" />
   </ItemGroup>
   <ItemGroup>
     <Reference Include="System.Runtime" />

src/libraries/System.Collections.NonGeneric/src/System/Collections/SortedList.cs

@@ -11,6 +11,7 @@
 **
 ===========================================================*/
 
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
@@ -351,12 +352,12 @@ public virtual void CopyTo(Array array, int arrayIndex)
         // KeyValuePairs is different from Dictionary Entry in that it has special
         // debugger attributes on its fields.
 
-        internal virtual KeyValuePairs[] ToKeyValuePairsArray()
+        internal virtual DebugViewDictionaryItem<object, object?>[] ToDebugViewDictionaryItemArray()
         {
-            KeyValuePairs[] array = new KeyValuePairs[Count];
+            var array = new DebugViewDictionaryItem<object, object?>[Count];
             for (int i = 0; i < Count; i++)
             {
-                array[i] = new KeyValuePairs(keys[i], values[i]);
+                array[i] = new DebugViewDictionaryItem<object, object?>(keys[i], values[i]);
             }
             return array;
         }
@@ -766,9 +767,9 @@ public override void SetByIndex(int index, object? value)
                 }
             }
 
-            internal override KeyValuePairs[] ToKeyValuePairsArray()
+            internal override DebugViewDictionaryItem<object, object?>[] ToDebugViewDictionaryItemArray()
             {
-                return _list.ToKeyValuePairsArray();
+                return _list.ToDebugViewDictionaryItemArray();
             }
 
             public override void TrimToSize()
@@ -1097,11 +1098,11 @@ public SortedListDebugView(SortedList sortedList)
             }
 
             [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
-            public KeyValuePairs[] Items
+            public DebugViewDictionaryItem<object, object?>[] Items
             {
                 get
                 {
-                    return _sortedList.ToKeyValuePairsArray();
+                    return _sortedList.ToDebugViewDictionaryItemArray();
                 }
             }
         }

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

@@ -7,6 +7,8 @@
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="System\Collections\BitArray.cs" />
+    <Compile Include="$(CoreLibSharedDir)System\Collections\Generic\DebugViewDictionaryItem.cs"
+             Link="Common\System\Collections\Generic\DebugViewDictionaryItem.cs" />
     <Compile Include="$(CoreLibSharedDir)System\Collections\Generic\ICollectionDebugView.cs"
              Link="Common\System\Collections\Generic\ICollectionDebugView.cs" />
     <Compile Include="$(CoreLibSharedDir)System\Collections\Generic\IDictionaryDebugView.cs"

src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems

@@ -181,6 +181,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\CollectionExtensions.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\Comparer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\Dictionary.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\DebugViewDictionaryItem.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\EqualityComparer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\HashSet.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\HashSetEqualityComparer.cs" />
@@ -225,7 +226,6 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\IList.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\IStructuralComparable.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\IStructuralEquatable.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Collections\KeyValuePairs.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\ListDictionaryInternal.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\ObjectModel\Collection.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\ObjectModel\CollectionHelpers.cs" />

src/libraries/System.Private.CoreLib/src/System/Collections/Generic/DebugViewDictionaryItem.cs

@@ -0,0 +1,32 @@
+// 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
+{
+    /// <summary>
+    /// Defines a key/value pair for displaying an item of a dictionary by a debugger.
+    /// </summary>
+    [DebuggerDisplay("{Value}", Name = "[{Key}]")]
+    internal readonly struct DebugViewDictionaryItem<K, V>
+    {
+        public DebugViewDictionaryItem(K key, V value)
+        {
+            Key = key;
+            Value = value;
+        }
+
+        public DebugViewDictionaryItem(KeyValuePair<K, V> keyValue)
+        {
+            Key = keyValue.Key;
+            Value = keyValue.Value;
+        }
+
+        [DebuggerBrowsable(DebuggerBrowsableState.Collapsed)]
+        public K Key { get; init; }
+
+        [DebuggerBrowsable(DebuggerBrowsableState.Collapsed)]
+        public V Value { get; init; }
+    }
+}

src/libraries/System.Private.CoreLib/src/System/Collections/Generic/IDictionaryDebugView.cs

@@ -17,12 +17,17 @@ public IDictionaryDebugView(IDictionary<K, V> dictionary)
         }
 
         [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
-        public KeyValuePair<K, V>[] Items
+        public DebugViewDictionaryItem<K, V>[] Items
         {
             get
             {
-                KeyValuePair<K, V>[] items = new KeyValuePair<K, V>[_dict.Count];
-                _dict.CopyTo(items, 0);
+                var keyValuePairs = new KeyValuePair<K, V>[_dict.Count];
+                _dict.CopyTo(keyValuePairs, 0);
+                var items = new DebugViewDictionaryItem<K, V>[keyValuePairs.Length];
+                for (int i = 0; i < items.Length; i++)
+                {
+                    items[i] = new DebugViewDictionaryItem<K, V>(keyValuePairs[i]);
+                }
                 return items;
             }
         }

src/libraries/System.Private.CoreLib/src/System/Collections/Hashtable.cs

@@ -11,6 +11,7 @@
 **
 ===========================================================*/
 
+using System.Collections.Generic;
 using System.ComponentModel;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
@@ -581,21 +582,17 @@ public virtual void CopyTo(Array array, int arrayIndex)
             CopyEntries(array, arrayIndex);
         }
 
-        // Copies the values in this Hashtable to an KeyValuePairs array.
-        // KeyValuePairs is different from Dictionary Entry in that it has special
-        // debugger attributes on its fields.
-
-        internal virtual KeyValuePairs[] ToKeyValuePairsArray()
+        internal virtual DebugViewDictionaryItem<object, object?>[] ToKeyValuePairsArray()
         {
-            KeyValuePairs[] array = new KeyValuePairs[_count];
+            var array = new DebugViewDictionaryItem<object, object?>[_count];
             int index = 0;
             Bucket[] lbuckets = _buckets;
             for (int i = lbuckets.Length; --i >= 0;)
             {
                 object? keyv = lbuckets[i].key;
                 if ((keyv != null) && (keyv != _buckets))
                 {
-                    array[index++] = new KeyValuePairs(keyv, lbuckets[i].val);
+                    array[index++] = new DebugViewDictionaryItem<object, object?>(keyv, lbuckets[i].val);
                 }
             }
 
@@ -1385,7 +1382,7 @@ public override void OnDeserialization(object? sender)
                 // call OnDeserialization on our parent table.
             }
 
-            internal override KeyValuePairs[] ToKeyValuePairsArray()
+            internal override DebugViewDictionaryItem<object, object?>[] ToKeyValuePairsArray()
             {
                 return _table.ToKeyValuePairsArray();
             }
@@ -1509,7 +1506,7 @@ public HashtableDebugView(Hashtable hashtable)
             }
 
             [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
-            public KeyValuePairs[] Items => _hashtable.ToKeyValuePairsArray();
+            public DebugViewDictionaryItem<object, object?>[] Items => _hashtable.ToKeyValuePairsArray();
         }
     }
 }

src/libraries/System.Private.CoreLib/src/System/Collections/ListDictionaryInternal.cs

@@ -1,5 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 
@@ -418,15 +419,15 @@ public ListDictionaryInternalDebugView(ListDictionaryInternal list)
             }
 
             [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
-            public KeyValuePairs[] Items
+            public DebugViewDictionaryItem<object, object?>[] Items
             {
                 get
                 {
-                    var array = new KeyValuePairs[_list.count];
+                    var array = new DebugViewDictionaryItem<object, object?>[_list.count];
                     int index = 0;
                     for (DictionaryNode? node = _list.head; node != null; node = node.next)
                     {
-                        array[index++] = new KeyValuePairs(node.key, node.value);
+                        array[index++] = new DebugViewDictionaryItem<object, object?>(node.key, node.value);
                     }
                     return array;
                 }