[TrimmableTypeMap] Add GetStaticMethodFallbackTypesCore override for desugared default interface methods

src/Mono.Android/Microsoft.Android.Runtime/TrimmableTypeMapTypeManager.cs

@@ -60,6 +60,18 @@ protected override IEnumerable<string> GetSimpleReferences (Type type)
 		return base.GetInvokerTypeCore (type);
 	}
 
+	protected override IReadOnlyList<string>? GetStaticMethodFallbackTypesCore (string jniSimpleReference)
+	{
+		int slash = jniSimpleReference.LastIndexOf ('/');
+		var desugarType = slash > 0
+			? $"{jniSimpleReference.Substring (0, slash + 1)}Desugar{jniSimpleReference.Substring (slash + 1)}"
+			: $"Desugar{jniSimpleReference}";
+		return new[] {
+			$"{desugarType}$_CC",
+			$"{jniSimpleReference}$-CC",
+		};
+	}
+
 	public override void RegisterNativeMembers (
 			JniType nativeClass,
 			[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods | DynamicallyAccessedMemberTypes.NonPublicMethods | DynamicallyAccessedMemberTypes.NonPublicNestedTypes)]

tests/Mono.Android-Tests/Mono.Android-Tests/Java.Interop/TrimmableTypeMapTypeManagerTests.cs

@@ -0,0 +1,50 @@
+using Java.Interop;
+using Microsoft.Android.Runtime;
+using NUnit.Framework;
+
+namespace Java.InteropTests
+{
+	[TestFixture]
+	public class TrimmableTypeMapTypeManagerTests
+	{
+		// Test subclass that allows instantiation without full TrimmableTypeMap initialization.
+		// GetStaticMethodFallbackTypesCore does not use TrimmableTypeMap.Instance, so the test
+		// can run without an initialized TrimmableTypeMap singleton.
+		sealed class TestableTrimmableTypeMapTypeManager : TrimmableTypeMapTypeManager
+		{
+		}
+
+		[Test]
+		public void GetStaticMethodFallbackTypes_WithPackageName_ReturnsDesugarFallbacks ()
+		{
+			using var manager = new TestableTrimmableTypeMapTypeManager ();
+			var fallbacks = manager.GetStaticMethodFallbackTypes ("android/app/Activity");
+			Assert.IsNotNull (fallbacks);
+			Assert.AreEqual (2, fallbacks!.Count);
+			Assert.AreEqual ("android/app/DesugarActivity$_CC", fallbacks [0]);
+			Assert.AreEqual ("android/app/Activity$-CC", fallbacks [1]);
+		}
+
+		[Test]
+		public void GetStaticMethodFallbackTypes_WithoutPackageName_ReturnsDesugarFallbacks ()
+		{
+			using var manager = new TestableTrimmableTypeMapTypeManager ();
+			var fallbacks = manager.GetStaticMethodFallbackTypes ("Activity");
+			Assert.IsNotNull (fallbacks);
+			Assert.AreEqual (2, fallbacks!.Count);
+			Assert.AreEqual ("DesugarActivity$_CC", fallbacks [0]);
+			Assert.AreEqual ("Activity$-CC", fallbacks [1]);
+		}
+
+		[Test]
+		public void GetStaticMethodFallbackTypes_WithDeepPackageName_ReturnsDesugarFallbacks ()
+		{
+			using var manager = new TestableTrimmableTypeMapTypeManager ();
+			var fallbacks = manager.GetStaticMethodFallbackTypes ("com/example/package/MyInterface");
+			Assert.IsNotNull (fallbacks);
+			Assert.AreEqual (2, fallbacks!.Count);
+			Assert.AreEqual ("com/example/package/DesugarMyInterface$_CC", fallbacks [0]);
+			Assert.AreEqual ("com/example/package/MyInterface$-CC", fallbacks [1]);
+		}
+	}
+}

tests/Mono.Android-Tests/Mono.Android-Tests/Mono.Android.NET-Tests.csproj

@@ -98,6 +98,7 @@
     <Compile Include="Java.Interop\JavaListTest.cs" />
     <Compile Include="Java.Interop\JavaObjectExtensionsTests.cs" />
     <Compile Include="Java.Interop\JnienvTest.cs" />
+    <Compile Include="Java.Interop\TrimmableTypeMapTypeManagerTests.cs" />
     <Compile Include="Java.Lang\ObjectArrayMarshaling.cs" />
     <Compile Include="Java.Lang\ObjectTest.cs" />
     <Compile Include="Localization\LocalizationTests.cs" />