Minor changes to IIDOptimizer and AOTOptimizer (#1626)

* Fix value type assignment scenarios getting misdetected

* Make IIDOptimizer not write binary if it patched nothing

* Fix return code and remove message which has caused confusion in the past

src/Authoring/WinRT.SourceGenerator/AotOptimizer.cs

@@ -943,7 +943,9 @@ void AddVtableAttributesForType(Microsoft.CodeAnalysis.TypeInfo instantiatedType
  // type need to be put on the CCW.
  if (instantiatedType.Type is IArrayTypeSymbol arrayType)
  {
- if (convertedToTypeSymbol is not IArrayTypeSymbol)
+ if (convertedToTypeSymbol is not IArrayTypeSymbol &&
+ // Make sure we aren't just assigning it to a value type such as ReadOnlySpan
+ !convertedToTypeSymbol.IsValueType)
  {
  if (visitedTypes.Contains(arrayType))
  {

src/Perf/IIDOptimizer/Program.cs

@@ -121,19 +121,28 @@ private static int GuidPatch(string targetAssembly, string outputDirectory, IEnu
  var winRTRuntimeAssembly = ResolveWinRTRuntime(targetAssemblyDefinition, resolver);
  if (winRTRuntimeAssembly is null)
  {
- Console.WriteLine("Failed to resolve WinRT.Runtime.dll.");
  return -1;
  }
 
  var guidPatcher = new GuidPatcher(winRTRuntimeAssembly, targetAssemblyDefinition);
 
- int numPatches = guidPatcher.ProcessAssembly(); 
+ int numPatches = guidPatcher.ProcessAssembly();
+ Console.WriteLine($"{numPatches} IID calculations/fetches patched");
 
- guidPatcher.SaveAssembly(outputDirectory);
-
- Console.WriteLine($"Saved patched .dll to {outputDirectory}");
- Console.WriteLine($"{numPatches} IID calculations/fetches patched"); 
- return 0; 
+ // Only write assembly if we actually patched anything.
+ // Otherwise we would just write a type we use as part of our implementation
+ // when it is actually not needed.
+ if (numPatches > 0)
+ {
+ guidPatcher.SaveAssembly(outputDirectory);
+ Console.WriteLine($"Saved patched .dll to {outputDirectory}");
+ return 0;
+ }
+ else
+ {
+ // Exit code is checked by caller to copy patched file over.
+ return -1;
+ }
  }
  catch (AssemblyResolutionException e)
  {