KeyedCollection debug view doesn't work

dotnet · eiriktsarpalis · Jan 12, 2024 · Dec 21, 2023 · Jan 3, 2024 · Jan 4, 2024
commit 172fb27ca67d9cf2e3c4cabb3ad7892c3895877a
diff --git a/src/libraries/System.ObjectModel/src/System/Collections/ObjectModel/KeyedCollection.cs b/src/libraries/System.ObjectModel/src/System/Collections/ObjectModel/KeyedCollection.cs
@@ -8,7 +8,7 @@
 namespace System.Collections.ObjectModel
 {
     [Serializable]
-    [DebuggerTypeProxy(typeof(CollectionDebugView<>))]
+    [DebuggerTypeProxy(typeof(KeyedCollection<,>.KeyedCollectionDebugView))]
     [DebuggerDisplay("Count = {Count}")]
     [System.Runtime.CompilerServices.TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
     public abstract class KeyedCollection<TKey, TItem> : Collection<TItem> where TKey : notnull
@@ -280,5 +280,53 @@ private void RemoveKey(TKey key)
                 keyCount--;
             }
         }
+
+        internal sealed class KeyedCollectionDebugView
+        {
+            private readonly KeyedCollection<TKey, TItem> _collection;
+
+            public KeyedCollectionDebugView(KeyedCollection<TKey, TItem> collection)
+            {
+                ArgumentNullException.ThrowIfNull(collection);
+                _collection = collection;
+            }
+
+            [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
+            public KeyedCollectionDebugViewItem[] Items
+            {
+                get
+                {
+                    var items = new KeyedCollectionDebugViewItem[_collection.Count];
+                    for (int i = 0; i < items.Length; i++)
+                    {
+                        TItem item = _collection[i];
+                        items[i] = new KeyedCollectionDebugViewItem(_collection.GetKeyForItem(item), item);
+                    }
+                    return items;
+                }
+            }
+        }
+
+        [DebuggerDisplay("{Value}", Name = "[{Key}]")]
+        internal readonly struct KeyedCollectionDebugViewItem
+        {
+            public KeyedCollectionDebugViewItem(TKey key, TItem value)
+            {
+                Key = key;
+                Value = value;
+            }
+
+            public KeyedCollectionDebugViewItem(KeyValuePair<TKey, TItem> keyValue)
+            {
+                Key = keyValue.Key;
+                Value = keyValue.Value;
+            }
+
+            [DebuggerBrowsable(DebuggerBrowsableState.Collapsed)]
+            public TKey Key { get; }
+
+            [DebuggerBrowsable(DebuggerBrowsableState.Collapsed)]
+            public TItem Value { get; }
+        }
     }
 }