[Debug] IndexOutOfRangeException when extension data doesn't have two…

… generic parameters (#33014) * added generic param tests * added proposed fix * fixed debug statements to use underlying dictionary type * removed baseline comment * removed casts to idictionary * using explicitly typed variable Co-Authored-By: Layomi Akinrinade <layomia@gmail.com> Co-authored-by: Layomi Akinrinade <layomia@gmail.com>
dotnet · Mar 2, 2020 · 71deb1e · 71deb1e
1 parent 0bf721a
commit 71deb1e
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Showing 3 changed files with 40 additions and 8 deletions.
diff --git a/...em.Text.Json/src/System/Text/Json/Serialization/JsonSerializer.Read.HandlePropertyName.cs b/...em.Text.Json/src/System/Text/Json/Serialization/JsonSerializer.Read.HandlePropertyName.cs
@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Collections;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using System.Text.Json.Serialization;
@@ -106,23 +107,27 @@ private static void CreateDataExtensionProperty(
         {
             Debug.Assert(jsonPropertyInfo != null);
 
-            IDictionary? extensionData = (IDictionary?)jsonPropertyInfo.GetValueAsObject(obj);
+            object? extensionData = jsonPropertyInfo.GetValueAsObject(obj);
             if (extensionData == null)
             {
                 // Create the appropriate dictionary type. We already verified the types.
-                Debug.Assert(jsonPropertyInfo.DeclaredPropertyType.IsGenericType);
-                Debug.Assert(jsonPropertyInfo.DeclaredPropertyType.GetGenericArguments().Length == 2);
-                Debug.Assert(jsonPropertyInfo.DeclaredPropertyType.GetGenericArguments()[0].UnderlyingSystemType == typeof(string));
-                Debug.Assert(
-                    jsonPropertyInfo.DeclaredPropertyType.GetGenericArguments()[1].UnderlyingSystemType == typeof(object) ||
-                    jsonPropertyInfo.DeclaredPropertyType.GetGenericArguments()[1].UnderlyingSystemType == typeof(JsonElement));
+#if DEBUG
+                Type underlyingIDictionaryType = jsonPropertyInfo.DeclaredPropertyType.GetCompatibleGenericInterface(typeof(IDictionary<,>))!;
+                Type[] genericArgs = underlyingIDictionaryType.GetGenericArguments();
 
+                Debug.Assert(underlyingIDictionaryType.IsGenericType);
+                Debug.Assert(genericArgs.Length == 2);
+                Debug.Assert(genericArgs[0].UnderlyingSystemType == typeof(string));
+                Debug.Assert(
+                    genericArgs[1].UnderlyingSystemType == typeof(object) ||
+                    genericArgs[1].UnderlyingSystemType == typeof(JsonElement));
+#endif
                 if (jsonPropertyInfo.RuntimeClassInfo.CreateObject == null)
                 {
                     ThrowHelper.ThrowNotSupportedException_SerializationNotSupported(jsonPropertyInfo.DeclaredPropertyType);
                 }
 
-                extensionData = (IDictionary?)jsonPropertyInfo.RuntimeClassInfo.CreateObject();
+                extensionData = jsonPropertyInfo.RuntimeClassInfo.CreateObject();
                 jsonPropertyInfo.SetValueAsObject(obj, extensionData);
             }
 

diff --git a/src/libraries/System.Text.Json/tests/Serialization/ExtensionDataTests.cs b/src/libraries/System.Text.Json/tests/Serialization/ExtensionDataTests.cs
@@ -770,6 +770,31 @@ private class ClassWithExtensionPropertyCustomIImmutableJsonElement
             public GenericIImmutableDictionaryWrapper<string, JsonElement> MyOverflow { get; set; }
         }
 
+        [Fact]
+        public static void DeserializeIntoGenericDictionaryParameterCount()
+        {
+            JsonSerializer.Deserialize<ClassWithExtensionPropertyNoGenericParameters>("{\"hello\":\"world\"}");
+            JsonSerializer.Deserialize<ClassWithExtensionPropertyOneGenericParameter>("{\"hello\":\"world\"}");
+            JsonSerializer.Deserialize<ClassWithExtensionPropertyThreeGenericParameters>("{\"hello\":\"world\"}");
+        }
+
+        private class ClassWithExtensionPropertyNoGenericParameters
+        {
+            [JsonExtensionData]
+            public StringToObjectIDictionaryWrapper MyOverflow { get; set; }
+        }
+
+        private class ClassWithExtensionPropertyOneGenericParameter
+        {
+            [JsonExtensionData]
+            public StringToGenericIDictionaryWrapper<object> MyOverflow { get; set; }
+        }
+
+        private class ClassWithExtensionPropertyThreeGenericParameters
+        {
+            [JsonExtensionData]
+            public GenericIDictonaryWrapperThreeGenericParameters<string, object, string> MyOverflow { get; set; }
+        }
 
         [Fact]
         public static void CustomObjectConverterInExtensionProperty()

diff --git a/src/libraries/System.Text.Json/tests/Serialization/TestClasses.GenericCollections.cs b/src/libraries/System.Text.Json/tests/Serialization/TestClasses.GenericCollections.cs
@@ -866,6 +866,8 @@ public class GenericIDictionaryWrapperPrivateConstructor<TKey, TValue> : Generic
         private GenericIDictionaryWrapperPrivateConstructor() { }
     }
 
+    public class GenericIDictonaryWrapperThreeGenericParameters<TKey, TValue, TUnused> : GenericIDictionaryWrapper<TKey, TValue> { }
+
     public class ReadOnlyStringToStringIDictionaryWrapper : StringToStringIDictionaryWrapper
     {
         public override bool IsReadOnly => true;