Fix configuration binding with types implementing IDictionary

src/libraries/Microsoft.Extensions.Configuration.Binder/src/ConfigurationBinder.cs

@@ -589,12 +589,13 @@ private static void BindConcreteDictionary(
 
             Debug.Assert(dictionary is not null);
 
-            Type dictionaryObjectType = dictionary.GetType();
+            Type? iDictionaryObjectType = FindOpenGenericInterface(typeof(IDictionary<,>), dictionary.GetType());
 
-            MethodInfo tryGetValue = dictionaryObjectType.GetMethod("TryGetValue", BindingFlags.Public | BindingFlags.Instance)!;
+            Debug.Assert(iDictionaryObjectType is not null);
+
+            MethodInfo tryGetValue = iDictionaryObjectType.GetMethod("TryGetValue", DeclaredOnlyLookup)!;
+            PropertyInfo? setter = iDictionaryObjectType.GetProperty("Item", DeclaredOnlyLookup);
 
-            // dictionary should be of type Dictionary<,> or of type implementing IDictionary<,>
-            PropertyInfo? setter = dictionaryObjectType.GetProperty("Item", BindingFlags.Public | BindingFlags.Instance);
             if (setter is null || !setter.CanWrite)
             {
                 // Cannot set any item on the dictionary object.

src/libraries/Microsoft.Extensions.Configuration.Binder/tests/ConfigurationCollectionBindingTests.cs

@@ -1171,7 +1171,7 @@ public void CanBindInitializedCustomIndirectlyDerivedIEnumerableList()
         }
 
         [Fact]
-        public void CanBindInitializedIReadOnlyDictionaryAndDoesNotMofifyTheOriginal()
+        public void CanBindInitializedIReadOnlyDictionaryAndDoesNotModifyTheOriginal()
         {
             // A field declared as IEnumerable<T> that is instantiated with a class
             // that indirectly implements IEnumerable<T> is still bound, but with
@@ -1672,6 +1672,13 @@ public class ImplementerOfIDictionaryClass<TKey, TValue> : IDictionary<TKey, TVa
             public bool TryGetValue(TKey key, out TValue value) => _dict.TryGetValue(key, out value);
 
             System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() => _dict.GetEnumerator();
+
+            // The following are members which has same names as the IDictionary<,> members.
+            // Adding these to the test to ensure not getting System.Reflection.AmbiguousMatchException when we bind the dictionary.
+            private string? v;
+            public string? this[string key] { get => v; set => v = value; }
+            public bool TryGetValue() { return true; }
+
         }
 
         public class ExtendedDictionary<TKey, TValue> : Dictionary<TKey, TValue>