[linker] preserve interfaces on Java types

src/Xamarin.Android.Build.Tasks/Linker/MonoDroid.Tuner/MarkJavaObjects.cs

@@ -60,6 +60,9 @@ void PreserveJavaObjectImplementation (TypeDefinition type)
 			PreserveIntPtrConstructor (type);
 			PreserveAttributeSetConstructor (type);
 			PreserveInvoker (type);
+#if ILLINK
+			PreserveInterfaces (type);
+#endif // ILLINK
 		}
 
 		void PreserveAttributeSetConstructor (TypeDefinition type)
@@ -196,7 +199,63 @@ void PreserveInvoker (TypeDefinition type)
 			PreserveConstructors (type, invoker);
 			PreserveIntPtrConstructor (invoker);
 			PreserveInterfaceMethods (type, invoker);
+#if ILLINK
+			PreserveInterfaces (invoker);
+#endif // ILLINK
+		}
+
+#if ILLINK
+		void PreserveInterfaces (TypeDefinition type)
+		{
+			if (!type.HasInterfaces)
+				return;
+
+			if (!ShouldPreserveInterfaces (type))
+				return;
+
+			foreach (var iface in type.Interfaces) {
+				var td = iface.InterfaceType.Resolve ();
+				if (!td.ImplementsIJavaPeerable ())
+					continue;
+				Annotations.Mark (td);
+			}
+		}
+
+		// False if [Register(DoNotGenerateAcw=true)] is on the type
+		// False if [JniTypeSignature(GenerateJavaPeer=false)] is on the type
+		bool ShouldPreserveInterfaces (TypeDefinition type)
+		{
+			if (!type.HasCustomAttributes)
+				return true;
+
+			foreach (var attr in type.CustomAttributes) {
+				switch (attr.AttributeType.FullName) {
+					case "Android.Runtime.RegisterAttribute":
+						foreach (var property in attr.Properties) {
+							if (property.Name == "DoNotGenerateAcw") {
+								if (property.Argument.Value is bool value && value)
+									return false;
+								break;
+							}
+						}
+						break;
+					case "Java.Interop.JniTypeSignatureAttribute":
+						foreach (var property in attr.Properties) {
+							if (property.Name == "GenerateJavaPeer") {
+								if (property.Argument.Value is bool value && !value)
+									return false;
+								break;
+							}
+						}
+						break;
+					default:
+						break;
+				}
+			}
+
+			return true;
 		}
+#endif // ILLINK
 
 		TypeDefinition GetInvokerType (TypeDefinition type)
 		{

tests/MSBuildDeviceIntegration/Resources/LinkDescTest/MainActivityReplacement.cs

@@ -115,6 +115,9 @@ protected override void OnCreate(Bundle bundle)
 			// [Test] Post
 			Android.Util.Log.Info(TAG, HttpClientTest.Post ());
 
+			// [Test] TextChanged
+			Android.Util.Log.Info (TAG, MaterialTextChanged.TextChanged (this));
+
 			var cldt = new CustomLinkerDescriptionTests();
 			Android.Util.Log.Info(TAG, cldt.TryAccessNonXmlPreservedMethodOfLinkerModeFullClass());
 			Android.Util.Log.Info(TAG, LinkTestLib.Bug21578.MulticastOption_ShouldNotBeStripped());

tests/MSBuildDeviceIntegration/Resources/LinkDescTest/MaterialTextChanged.cs

@@ -0,0 +1,18 @@
+using System;
+using Android.Content;
+using Google.Android.Material.TextField;
+
+public class MaterialTextChanged
+{
+	// [Test]
+	public static string TextChanged (Context context)
+	{
+		try {
+			var view = new TextInputEditText (context);
+			view.TextChanged += (s, e) => { };
+			return $"[PASS] {nameof (MaterialTextChanged)}.{nameof (TextChanged)}";
+		} catch (Exception ex) {
+			return $"[FAIL] {nameof (MaterialTextChanged)}.{nameof (TextChanged)} FAILED: {ex}";
+		}
+	}
+}

tests/MSBuildDeviceIntegration/Tests/InstallAndRunTests.cs

@@ -421,6 +421,24 @@ public class LinkModeFullClass {
 					new BuildItem ("ProjectReference", "..\\Library1\\Library1.csproj"),
 					new BuildItem ("ProjectReference", "..\\LinkTestLib\\LinkTestLib.csproj"),
 				},
+				PackageReferences = {
+					KnownPackages.AndroidXMigration,
+					KnownPackages.AndroidXAppCompat,
+					KnownPackages.AndroidXAppCompatResources,
+					KnownPackages.AndroidXBrowser,
+					KnownPackages.AndroidXMediaRouter,
+					KnownPackages.AndroidXLegacySupportV4,
+					KnownPackages.AndroidXLifecycleLiveData,
+					KnownPackages.XamarinGoogleAndroidMaterial,
+				},
+				Sources = {
+					new BuildItem.Source ("MaterialTextChanged.cs") {
+						TextContent = () => {
+							using (var sr = new StreamReader (typeof (InstallAndRunTests).Assembly.GetManifestResourceStream ("Xamarin.Android.Build.Tests.Resources.LinkDescTest.MaterialTextChanged.cs")))
+								return sr.ReadToEnd ();
+						},
+					},
+				},
 				OtherBuildItems = {
 					new BuildItem ("LinkDescription", "linker.xml") {
 						TextContent = () => linkMode == AndroidLinkMode.SdkOnly ? "<linker/>" : @"