Remove ValueType support and reflection piece from TaskResultConverter

Update description to explicitly call out returning null instead of default if no task or task result not ready.

Author: michael-hawker

Microsoft.Toolkit.Uwp.UI/Converters/TaskResultConverter.cs

@@ -14,31 +14,21 @@ namespace Microsoft.Toolkit.Uwp.UI.Converters
     /// This is needed because accessing <see cref="Task{TResult}.Result"/> when the task has not
     /// completed yet will block the current thread and might cause a deadlock (eg. if the task was
     /// scheduled on the same synchronization context where the result is being retrieved from).
-    /// The methods in this converter will safely return <see langword="default"/> if the input
+    /// The methods in this converter will safely return <see langword="null"/> if the input
     /// task is not set yet, still running, has faulted, or has been canceled.
     /// </summary>
-    /// <seealso href="https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/default-values">Default values of C# types</seealso>
     public sealed class TaskResultConverter : IValueConverter
     {
         /// <inheritdoc/>
         public object Convert(object value, Type targetType, object parameter, string language)
         {
-            //// Check if we need to return a specific type, which only matters for value types where the default won't be null.
-            var hasValueTypeTarget = targetType is not null && targetType.IsValueType;
-            //// If we have a value type, then calculate it's default value to return, as we probably need it unless the task is completed.
-            var defaultValue = hasValueTypeTarget ? Activator.CreateInstance(targetType) : null;
-
             if (value is Task task)
             {
-                // If we have a task, check if we have a result now, otherwise the non-generic version of this
-                // function always returns null, so we want to use whatever we actually want the default value to be
-                // for our target type (in case it's a value type).
-                return task.GetResultOrDefault() ?? defaultValue;
+                return task.GetResultOrDefault();
             }
             else if (value is null)
             {
-                // If we have a value type, return that value, otherwise this will be null.
-                return defaultValue;
+                return null;
             }
 
             // Otherwise, we'll just pass through whatever value/result was given to us.

UnitTests/UnitTests.UWP/Converters/Test_TaskResultConverter.cs

@@ -17,6 +17,7 @@ public class Test_TaskResultConverter
     {
         [TestCategory("Converters")]
         [UITestMethod]
+        [Ignore] // Ignore this value type test. Behavior will return null currently and not default.
         public void Test_TaskResultConverter_Instance_Int32()
         {
             TaskResultConverter converter = new();
@@ -92,9 +93,15 @@ public void Test_TaskResultConverter_Instance_NullObject()
 
             Assert.AreEqual(null, converter.Convert(null, null, null, null));
 
-            Assert.AreEqual(0, (int)converter.Convert(null, typeof(int), null, null));
+            // TODO: Think there may still be a problem for value types in x:Bind expressions, represented by these tests here,
+            // but was going to be too big a change for 7.1.3, will have to get more feedback and evaluate later.
+            /*Assert.AreEqual(0, (int)converter.Convert(null, typeof(int), null, null));
 
-            Assert.AreEqual(false, (bool)converter.Convert(null, typeof(bool), null, null));
+            Assert.AreEqual(false, (bool)converter.Convert(null, typeof(bool), null, null));*/
+
+            Assert.AreEqual(null, converter.Convert(null, typeof(int), null, null));
+
+            Assert.AreEqual(null, converter.Convert(null, typeof(bool), null, null));
 
             Assert.AreEqual(null, (int?)converter.Convert(null, typeof(int?), null, null));