[Mono.Android] fix trimming warnings, part 2

This fixes the next set of trimmer warnings found via:

    <IsTrimmable>true</IsTrimmable>
    <EnableAotAnalyzer>true</EnableAotAnalyzer>

~~ JavaObjectExtensions ~~

`JavaCast<T>()` now requires `PublicConstructors` and
`NonPublicConstructors` because of `Activator.CreateInstance<T>()`.
This change bubbles up to various other types that have a
`Find*ById<T>()` method:

* `Activity`
* `Dialog`
* `FragmentManager`
* `View`
* `Window`

`GetInvokerType()` also has suppressions around `Assembly.GetType()`
and `Type.MakeGenericType()`. We track this for the future at:

dotnet#8724

~~ AndroidRuntime ~~

Update `[DynamicallyAccessedMembers]` based on changes to
`RegisterNativeMembers` in:

dotnet/java-interop@b8f6f88

~~ JNINativeWrapper ~~

`$(EnableAotAnalyzer)` found usage of `DynamicMethod`. Suppress for now,
as we track this for the future at:

dotnet#8724

~~ ResourceIdManager ~~

Usage of `Type.GetMethod ("UpdateIdValues")` leads to decoration of
`[ResourceDesignerAttribute]` with:

    [DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)]
    public string FullName { get; set; }

I also had to suppress warnings around `Assembly.GetType()`. This
*should* be OK, as `Resource.designer.cs` is always in the "root
assembly" of Android application projects.

~~ JavaProxyThrowable ~~

Suppress warning around `StackFrame.GetMethod()`, we already handle
null return values and exceptions. The existing code appears to be
"best effort" to provide additional stack trace information.

~~ TypeManager ~~

Suppress warning around a call to `Type.GetType()` with a string
passed in from Java. Not really much we can do yet, except rely on
`MarkJavaObjects` trimmer step.

Likely also a problem for the future:

dotnet#8724

src/Mono.Android/Android.App/Activity.cs

@@ -1,19 +1,27 @@
 using System;
-
+using System.Diagnostics.CodeAnalysis;
 using Android.Runtime;
 
 namespace Android.App {
 
 	partial class Activity {
 
-		public T? FindViewById<T> (int id)
+		internal const DynamicallyAccessedMemberTypes Constructors = DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.NonPublicConstructors;
+
+		public T? FindViewById<
+				[DynamicallyAccessedMembers (Constructors)]
+				T
+		> (int id)
 			where T : Android.Views.View
 		{
 			return this.FindViewById (id)!.JavaCast<T> ();
 		}
 
 		// See: https://cs.android.com/android/platform/superproject/+/master:frameworks/base/core/java/android/app/Activity.java;l=3430
-		public T RequireViewById<T> (int id)
+		public T RequireViewById<
+				[DynamicallyAccessedMembers (Constructors)]
+				T
+		> (int id)
 			where T : Android.Views.View
 		{
 			var view = FindViewById<T> (id);

src/Mono.Android/Android.App/Dialog.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using Android.Runtime;
 
 namespace Android.App {
@@ -8,7 +9,10 @@ public partial class Dialog {
 		protected Dialog (Android.Content.Context context, bool cancelable, EventHandler cancelHandler) 
 			: this (context, cancelable, new Android.Content.IDialogInterfaceOnCancelListenerImplementor () { Handler = cancelHandler }) {}
 
-		public T? FindViewById<T> (int id)
+		public T? FindViewById<
+				[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.NonPublicConstructors)]
+				T
+		> (int id)
 			where T : Android.Views.View
 		{
 			return this.FindViewById (id).JavaCast<T> ();

src/Mono.Android/Android.App/FragmentManager.cs

@@ -1,18 +1,32 @@
 using Android.OS;
 using Android.Runtime;
+using System.Diagnostics.CodeAnalysis;
 
 #if ANDROID_11
 namespace Android.App {
 	public partial class FragmentManager {
-		public T? FindFragmentById<T> (int id) where T : Fragment
+		const DynamicallyAccessedMemberTypes Constructors = DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.NonPublicConstructors;
+
+		public T? FindFragmentById<
+				[DynamicallyAccessedMembers (Constructors)]
+				T
+		> (int id) where T : Fragment
 		{
 			return FindFragmentById (id).JavaCast<T> ();
 		}
-		public T? FindFragmentByTag<T> (string tag) where T : Fragment
+
+		public T? FindFragmentByTag<
+				[DynamicallyAccessedMembers (Constructors)]
+				T
+		> (string tag) where T : Fragment
 		{
 			return FindFragmentByTag (tag).JavaCast<T> ();
 		}
-		public T? GetFragment<T> (Bundle bundle, string key) where T : Fragment
+
+		public T? GetFragment<
+				[DynamicallyAccessedMembers (Constructors)]
+				T
+		> (Bundle bundle, string key) where T : Fragment
 		{
 			return GetFragment (bundle, key).JavaCast<T> ();
 		}

src/Mono.Android/Android.Runtime/AndroidRuntime.cs

@@ -247,6 +247,9 @@ struct JniRemappingReplacementMethod
 
 		bool jniAddNativeMethodRegistrationAttributePresent;
 
+		const DynamicallyAccessedMemberTypes Methods = DynamicallyAccessedMemberTypes.PublicMethods | DynamicallyAccessedMemberTypes.NonPublicMethods;
+		const DynamicallyAccessedMemberTypes MethodsAndPrivateNested = Methods | DynamicallyAccessedMemberTypes.NonPublicNestedTypes;
+
 		public AndroidTypeManager (bool jniAddNativeMethodRegistrationAttributePresent)
 		{
 			this.jniAddNativeMethodRegistrationAttributePresent = jniAddNativeMethodRegistrationAttributePresent;
@@ -473,7 +476,7 @@ static bool CallRegisterMethodByIndex (JniNativeMethodRegistrationArguments argu
 
 		public override void RegisterNativeMembers (
 				JniType nativeClass,
-				[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods | DynamicallyAccessedMemberTypes.NonPublicMethods)]
+				[DynamicallyAccessedMembers (MethodsAndPrivateNested)]
 				Type type,
 				string? methods) =>
 			RegisterNativeMembers (nativeClass, type, methods.AsSpan ());
@@ -483,7 +486,7 @@ public override void RegisterNativeMembers (
 		[UnconditionalSuppressMessage ("Trimming", "IL2072", Justification = "Delegate.CreateDelegate() can never statically know the string value parsed from parameter 'methods'.")]
 		public void RegisterNativeMembers (
 				JniType nativeClass,
-				[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods | DynamicallyAccessedMemberTypes.NonPublicMethods)] Type type,
+				[DynamicallyAccessedMembers (MethodsAndPrivateNested)] Type type,
 				ReadOnlySpan<char> methods)
 		{
 			try {
@@ -619,7 +622,11 @@ public override void WaitForGCBridgeProcessing ()
 			AndroidRuntimeInternal.WaitForBridgeProcessing ();
 		}
 
-		public override IJavaPeerable? CreatePeer (ref JniObjectReference reference, JniObjectReferenceOptions options, Type? targetType)
+		public override IJavaPeerable? CreatePeer (
+				ref JniObjectReference reference,
+				JniObjectReferenceOptions options,
+				[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.NonPublicConstructors)]
+				Type? targetType)
 		{
 			if (!reference.IsValid)
 				return null;

src/Mono.Android/Android.Runtime/Extensions.cs

@@ -7,7 +7,10 @@ namespace Android.Runtime {
 	public static class Extensions {
 
 		[return: NotNullIfNotNull ("instance")]
-		public static TResult? JavaCast<TResult> (this IJavaObject? instance)
+		public static TResult? JavaCast<
+				[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.NonPublicConstructors)]
+				TResult
+		> (this IJavaObject? instance)
 			where TResult : class, IJavaObject
 		{
 			return Java.Interop.JavaObjectExtensions.JavaCast<TResult>(instance);

src/Mono.Android/Android.Runtime/JNINativeWrapper.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 using System.Reflection.Emit;
 using System.Threading;
@@ -52,7 +53,11 @@ public static Delegate CreateDelegate (Delegate dlg)
 				param_types [i] = parameters [i].ParameterType;
 			}
 
+			// FIXME: https://github.com/xamarin/xamarin-android/issues/8724
+			// IL3050 disabled in source: if someone uses NativeAOT, they will get the warning.
+			#pragma warning disable IL3050
 			var dynamic = new DynamicMethod (DynamicMethodNameCounter.GetUniqueName (), ret_type, param_types, typeof (DynamicMethodNameCounter), true);
+			#pragma warning restore IL3050
 			var ig = dynamic.GetILGenerator ();
 
 			LocalBuilder? retval = null;

src/Mono.Android/Android.Runtime/JavaProxyThrowable.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 
 using StackTraceElement = Java.Lang.StackTraceElement;
@@ -38,6 +39,14 @@ public static JavaProxyThrowable Create (Exception innerException)
 
 		void TranslateStackTrace ()
 		{
+			// FIXME: https://github.com/xamarin/xamarin-android/issues/8724
+			// StackFrame.GetMethod() will return null under NativeAOT;
+			// However, you can still get useful information from StackFrame.ToString():
+			// MainActivity.OnCreate() + 0x37 at offset 55 in file:line:column <filename unknown>:0:0
+			[UnconditionalSuppressMessage ("Trimming", "IL2026", Justification = "StackFrame.GetMethod() is \"best attempt\", we handle null & exceptions")]
+			static MethodBase? StackFrameGetMethod (StackFrame frame) =>
+				frame.GetMethod ();
+
 			var trace = new StackTrace (InnerException, fNeedFileInfo: true);
 			if (trace.FrameCount <= 0) {
 				return;
@@ -59,7 +68,7 @@ void TranslateStackTrace ()
 
 			for (int i = 0; i < frames.Length; i++) {
 				StackFrame managedFrame = frames[i];
-				MethodBase? managedMethod = managedFrame.GetMethod ();
+				MethodBase? managedMethod = StackFrameGetMethod (managedFrame);
 
 				var throwableFrame = new StackTraceElement (
 					declaringClass: managedMethod?.DeclaringType?.FullName,

src/Mono.Android/Android.Runtime/ResourceDesignerAttribute.cs

@@ -1,15 +1,19 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 
 namespace Android.Runtime
 {
 	[AttributeUsage (AttributeTargets.Assembly)]
 	public class ResourceDesignerAttribute : Attribute
 	{
-		public ResourceDesignerAttribute (string fullName)
+		public ResourceDesignerAttribute (
+				[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)]
+				string fullName)
 		{
 			FullName = fullName;
 		}
 
+		[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)]
 		public string FullName { get; set; }
 
 		public bool IsApplication { get; set; }

src/Mono.Android/Android.Runtime/ResourceIdManager.cs

@@ -31,12 +31,19 @@ public static void UpdateIdValues ()
 			}
 		}
 
-		[UnconditionalSuppressMessage ("Trimming", "IL2026", Justification = "Types in Resource.designer.cs are preserved, because it is the root assembly passed to the linker.")]
+		[return: DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)]
 		static Type? GetResourceTypeFromAssembly (Assembly assembly)
 		{
+			const string rootAssembly = "Types in Resource.designer.cs are preserved, because it is the @(TrimmerRootAssembly).";
+
+			[UnconditionalSuppressMessage ("Trimming", "IL2026", Justification = rootAssembly)]
+			[UnconditionalSuppressMessage ("Trimming", "IL2073", Justification = rootAssembly)]
+			[return: DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)]
+			static Type AssemblyGetType (Assembly a, string name) => a.GetType (name);
+
 			foreach (var customAttribute in assembly.GetCustomAttributes (typeof (ResourceDesignerAttribute), true)) {
 				if (customAttribute is ResourceDesignerAttribute resourceDesignerAttribute && resourceDesignerAttribute.IsApplication) {
-					var type = assembly.GetType (resourceDesignerAttribute.FullName);
+					var type = AssemblyGetType (assembly, resourceDesignerAttribute.FullName);
 					if (type != null)
 						return type;
 				}

src/Mono.Android/Android.Views/View.cs

@@ -14,6 +14,8 @@ public enum SystemUiFlags {
 
 	public partial class View {
 
+		internal const DynamicallyAccessedMemberTypes Constructors = DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.NonPublicConstructors;
+
 #if ANDROID_16
 		[Obsolete ("This method uses wrong enum type. Please use PerformAccessibilityAction(Action) instead.")]
 		public bool PerformAccessibilityAction (GlobalAction action, Bundle arguments)
@@ -22,14 +24,20 @@ public bool PerformAccessibilityAction (GlobalAction action, Bundle arguments)
 		}
 #endif
 
-		public T? FindViewById<T> (int id)
+		public T? FindViewById<
+				[DynamicallyAccessedMembers (Constructors)]
+				T
+		> (int id)
 			where T : Android.Views.View
 		{
 			return this.FindViewById (id).JavaCast<T> ();
 		}
 
 		// See: https://cs.android.com/android/platform/superproject/+/master:frameworks/base/core/java/android/view/View.java;l=25322
-		public T RequireViewById<T> (int id)
+		public T RequireViewById<
+				[DynamicallyAccessedMembers (Constructors)]
+				T
+		> (int id)
 			where T : Android.Views.View
 		{
 			var view = FindViewById<T> (id);

src/Mono.Android/Android.Views/Window.cs

@@ -6,7 +6,10 @@ namespace Android.Views {
 
 	partial class Window {
 
-		public T? FindViewById<T> (int id)
+		public T? FindViewById<
+				[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.NonPublicConstructors)]
+				T
+		> (int id)
 			where T : Android.Views.View
 		{
 			return this.FindViewById (id).JavaCast<T> ();

src/Mono.Android/Java.Interop/JavaObjectExtensions.cs

@@ -8,6 +8,7 @@
 namespace Java.Interop {
 
 	public static class JavaObjectExtensions {
+		const DynamicallyAccessedMemberTypes Constructors = DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.NonPublicConstructors;
 
 		[Obsolete ("Use Android.Runtime.JavaCollection.ToLocalJniHandle()")]
 		public static JavaCollection ToInteroperableCollection (this ICollection instance)
@@ -46,13 +47,19 @@ public static JavaDictionary<K,V> ToInteroperableCollection<K,V> (this IDictiona
 		}
 
 		[return: NotNullIfNotNull ("instance")]
-		public static TResult? JavaCast<TResult> (this IJavaObject? instance)
+		public static TResult? JavaCast<
+				[DynamicallyAccessedMembers (Constructors)]
+				TResult
+		> (this IJavaObject? instance)
 			where TResult : class, IJavaObject
 		{
 			return _JavaCast<TResult> (instance);
 		}
 
-		internal static TResult? _JavaCast<TResult> (this IJavaObject? instance)
+		internal static TResult? _JavaCast<
+				[DynamicallyAccessedMembers (Constructors)]
+				TResult
+		> (this IJavaObject? instance)
 		{
 			if (instance == null)
 				return default (TResult);
@@ -74,7 +81,10 @@ public static JavaDictionary<K,V> ToInteroperableCollection<K,V> (this IDictiona
 				throw new NotSupportedException (FormattableString.Invariant ($"Unable to convert type '{instance.GetType ().FullName}' to '{resultType.FullName}'."));
 		}
 
-		static IJavaObject CastClass (IJavaObject instance, Type resultType)
+		static IJavaObject CastClass (
+				IJavaObject instance,
+				[DynamicallyAccessedMembers (Constructors)]
+				Type resultType)
 		{
 			var klass = JNIEnv.FindClass (resultType);
 			try {
@@ -97,7 +107,10 @@ static IJavaObject CastClass (IJavaObject instance, Type resultType)
 			return (IJavaObject) TypeManager.CreateProxy (resultType, instance.Handle, JniHandleOwnership.DoNotTransfer);
 		}
 
-		internal static IJavaObject? JavaCast (IJavaObject? instance, Type resultType)
+		internal static IJavaObject? JavaCast (
+				IJavaObject? instance,
+				[DynamicallyAccessedMembers (Constructors)]
+				Type resultType)
 		{
 			if (resultType == null)
 				throw new ArgumentNullException ("resultType");
@@ -120,23 +133,43 @@ static IJavaObject CastClass (IJavaObject instance, Type resultType)
 
 		// typeof(Foo) -> FooInvoker
 		// typeof(Foo<>) -> FooInvoker`1
-		[UnconditionalSuppressMessage ("Trimming", "IL2026", Justification = "*Invoker types are preserved by the MarkJavaObjects linker step.")]
-		[UnconditionalSuppressMessage ("Trimming", "IL2055", Justification = "*Invoker types are preserved by the MarkJavaObjects linker step.")]
+		[return: DynamicallyAccessedMembers (Constructors)]
 		internal static Type? GetInvokerType (Type type)
 		{
+			const string InvokerTypes = "*Invoker types are preserved by the MarkJavaObjects linker step.";
+
+			[UnconditionalSuppressMessage ("Trimming", "IL2026", Justification = InvokerTypes)]
+			[UnconditionalSuppressMessage ("Trimming", "IL2055", Justification = InvokerTypes)]
+			[UnconditionalSuppressMessage ("Trimming", "IL2073", Justification = InvokerTypes)]
+			[return: DynamicallyAccessedMembers (Constructors)]
+			static Type? AssemblyGetType (Assembly assembly, string typeName) =>
+				assembly.GetType (typeName);
+
+			// FIXME: https://github.com/xamarin/xamarin-android/issues/8724
+			// IL3050 disabled in source: if someone uses NativeAOT, they will get the warning.
+			[UnconditionalSuppressMessage ("Trimming", "IL2055", Justification = InvokerTypes)]
+			[UnconditionalSuppressMessage ("Trimming", "IL2068", Justification = InvokerTypes)]
+			[return: DynamicallyAccessedMembers (Constructors)]
+			static Type MakeGenericType (Type type, params Type [] typeArguments) =>
+				#pragma warning disable IL3050
+				type.MakeGenericType (typeArguments);
+				#pragma warning restore IL3050
+
 			const string suffix = "Invoker";
+
 			Type[] arguments = type.GetGenericArguments ();
 			if (arguments.Length == 0)
-				return type.Assembly.GetType (type + suffix);
+				return AssemblyGetType (type.Assembly, type + suffix);
 			Type definition = type.GetGenericTypeDefinition ();
 			int bt = definition.FullName!.IndexOf ("`", StringComparison.Ordinal);
 			if (bt == -1)
 				throw new NotSupportedException ("Generic type doesn't follow generic type naming convention! " + type.FullName);
-			Type? suffixDefinition = definition.Assembly.GetType (
+			Type? suffixDefinition = AssemblyGetType (
+					definition.Assembly,
 					definition.FullName.Substring (0, bt) + suffix + definition.FullName.Substring (bt));
 			if (suffixDefinition == null)
 				return null;
-			return suffixDefinition.MakeGenericType (arguments);
+			return MakeGenericType (suffixDefinition, arguments);
 		}
 	}
 }

src/Mono.Android/Java.Interop/TypeManager.cs

@@ -237,6 +237,10 @@ static Exception CreateJavaLocationException ()
 
 		internal static Type? TypeRegistrationFallback (string class_name)
 		{
+			[UnconditionalSuppressMessage ("Trimming", "IL2057", Justification = "Type should be preserved by the MarkJavaObjects trimmer step.")]
+			static Type? TypeGetType (string name) =>
+				Type.GetType (name, throwOnError: false);
+
 			__TypeRegistrations.RegisterPackages ();
 
 			Type? type = null;
@@ -250,7 +254,7 @@ static Exception CreateJavaLocationException ()
 					return type;
 				}
 			}
-			if ((type = Type.GetType (JavaNativeTypeManager.ToCliType (class_name))) != null) {
+			if ((type = TypeGetType (JavaNativeTypeManager.ToCliType (class_name))) != null) {
 				return type;
 			}
 			return null;