[TrimmableTypeMap] Generator correctness fixes (#11988)

Java.Interop.ManagedPeer is a reflection-based helper marked
[RequiresUnreferencedCode] ("Uses reflection to find constructors and
invoke them."). The trimmable type map generator emitted a proxy for it
(_TypeMap.Proxies.Java_Interop_ManagedPeer_Proxy) whose constructor
references ManagedPeer's constructors, producing two IL2026 trim
warnings, aggregated by ILC into:

  IL2104: Assembly '_Java.Interop.TypeMap' produced trim warnings

Because the default NativeAOT type map is now trimmable, this surfaced as
a real MSBuild warning and broke NativeAOT tests that assert no warnings
(e.g. BuildWithJavaToolOptions).

ManagedPeer is not supported by the trimmable type map: on the trimmable
path native registration goes through IAndroidCallableWrapper.RegisterNatives
and ManagedPeerNativeRegistration is disabled, so ManagedPeer is never
activated via the type map. Exclude it in the scanner so no proxy is
emitted.

Verified on an arm64 emulator: the HelloWorld NativeAOT (trimmable)
sample now builds with 0 warnings and still launches to MainActivity.

### [TrimmableTypeMap] Emit <layout> element for the [Layout] attribute

The trimmable manifest generator already had ComponentElementBuilder support for
a <layout> child element, but the scanner never populated
ComponentInfo.LayoutProperties, so [Layout(...)] on an activity produced no
<layout> element (LayoutAttributeElement failed on NativeAOT).

Parse the [Layout] attribute's named properties in AssemblyIndex.ParseAttributes
(collected separately to tolerate attribute ordering, like [IntentFilter] and
[MetaData]) and flow them through TypeAttributeInfo.LayoutProperties into
ComponentInfo.LayoutProperties.

### [TrimmableTypeMap] Emit XA1010 for invalid $(AndroidManifestPlaceholders)

ManifestGenerator.ApplyPlaceholders already invoked a WarnInvalidPlaceholder
callback for placeholder entries without '=', but the callback was never wired
up, so the trimmable path silently dropped the XA1010 warning the legacy
ManifestDocument emits (ManifestPlaceHoldersXA1010 failed on NativeAOT).

Add ITrimmableTypeMapLogger.LogInvalidManifestPlaceholderWarning (logging
XA1010 from the MSBuild logger) and wire the ManifestGenerator instance's
WarnInvalidPlaceholder to it. The rooting-only PrepareManifestForRooting pass
stays silent so the warning is not emitted twice.

### [TrimmableTypeMap] Make generated typemap assemblies byte-deterministic

PEAssemblyBuilder.WritePE let ManagedPEBuilder fall back to a time-based PE
content id, so every regeneration of a typemap assembly produced different bytes
(different PE TimeDateStamp) even for identical input — the MVID was already
deterministic, but the image was not.

That churn broke incremental packaging on NativeAOT: an SDK CoreCompile rerun
(e.g. touching a .csproj.user file, which the SDK treats as a compile input)
rewrites the app assembly, reruns _GenerateTrimmableTypeMap, and — because the
regenerated *.TypeMap.dll got a fresh timestamp — forced _BuildApkEmbed to
repackage and _Sign to re-sign (CSProjUserFileChanges failed on NativeAOT).

Supply a deterministic content-id provider (SHA-256 over the serialized image)
so identical input yields byte-identical output; CopyIfStreamChanged then keeps
the existing file/timestamp and downstream targets stay incremental.

### [TrimmableTypeMap] Resolve java/lang/Object to Java.Lang.Object

For a JNI name mapped by multiple managed types (an alias group), the trimmable type map's
GetTypeForSimpleReference returns the first (index [0]) alias. Order the aliases to match the
native runtime's java->managed selection (clr_typemap_java_to_managed / monovm_typemap_java_to_managed,
built by NativeTypeMappingData): the Mono.Android module is processed first and the first managed
type to claim a Java name wins. So java/lang/Object must resolve to Java.Lang.Object (Mono.Android),
not Java.Interop.JavaObject (Java.Interop).

Order alias peers Mono.Android-assembly-first, with an ordinal managed-name tiebreak for
deterministic proxy naming.

Author: simonrozsival

src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/ComponentElementBuilder.cs

@@ -44,8 +44,7 @@ static class ComponentElementBuilder
 			element.Add (CreateIntentFilterElement (intentFilter));
 		}
 
-		// Add <layout> element from a [Layout] attribute, if present
-		if (component.LayoutProperties is not null) {
+		if (component.Kind == ComponentKind.Activity && component.LayoutProperties is not null) {
 			var layout = CreateLayoutElement (component.LayoutProperties);
 			if (layout is not null) {
 				element.Add (layout);

src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/ManifestGenerator.cs

@@ -516,7 +516,7 @@ internal static void ApplyPlaceholders (XDocument doc, string? placeholders, str
 		if (!placeholders.IsNullOrEmpty ()) {
 			foreach (var entry in placeholders.Split (PlaceholderSeparators, StringSplitOptions.RemoveEmptyEntries)) {
 				var eqIndex = entry.IndexOf ('=');
-				if (eqIndex > 0) {
+				if (eqIndex >= 0) {
 					var key = entry.Substring (0, eqIndex).Trim ();
 					var value = entry.Substring (eqIndex + 1).Trim ();
 					replacements ["${" + key + "}"] = value;

src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/ModelBuilder.cs

@@ -102,9 +102,8 @@ public static TypeMapAssemblyData Build (IReadOnlyList<JavaPeerInfo> peers, stri
 			string jniName = kvp.Key;
 			var peersForName = kvp.Value;
 
-			// Sort aliases by managed type name for deterministic proxy naming
 			if (peersForName.Count > 1) {
-				peersForName.Sort ((a, b) => StringComparer.Ordinal.Compare (a.ManagedTypeName, b.ManagedTypeName));
+				peersForName.Sort (CompareAliasesForRuntimeResolution);
 			}
 
 			EmitPeers (model, jniName, peersForName, assemblyName, usedProxyNames);
@@ -141,6 +140,19 @@ public static TypeMapAssemblyData Build (IReadOnlyList<JavaPeerInfo> peers, stri
 		return model;
 	}
 
+	static int CompareAliasesForRuntimeResolution (JavaPeerInfo a, JavaPeerInfo b)
+	{
+		// Keep alias [0] aligned with the native java→managed map, which processes Mono.Android first.
+		bool aMonoAndroid = string.Equals (a.AssemblyName, "Mono.Android", StringComparison.Ordinal);
+		bool bMonoAndroid = string.Equals (b.AssemblyName, "Mono.Android", StringComparison.Ordinal);
+		if (aMonoAndroid != bMonoAndroid) {
+			return aMonoAndroid ? -1 : 1;
+		}
+
+		int result = StringComparer.Ordinal.Compare (a.ManagedTypeName, b.ManagedTypeName);
+		return result != 0 ? result : StringComparer.Ordinal.Compare (a.AssemblyName, b.AssemblyName);
+	}
+
 	static void EmitPeers (TypeMapAssemblyData model, string jniName,
 		List<JavaPeerInfo> peersForName, string assemblyName, HashSet<string> usedProxyNames)
 	{

src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/PEAssemblyBuilder.cs

@@ -1,11 +1,13 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Reflection;
 using System.Reflection.Metadata;
 using System.Reflection.Metadata.Ecma335;
 using System.Reflection.PortableExecutable;
+using System.Security.Cryptography;
 
 namespace Microsoft.Android.Sdk.TrimmableTypeMap;
 
@@ -107,12 +109,28 @@ public void WritePE (Stream stream)
 			new PEHeaderBuilder (imageCharacteristics: Characteristics.Dll),
 			new MetadataRootBuilder (Metadata),
 			ILBuilder,
-			mappedFieldData: _mappedFieldData.Count > 0 ? _mappedFieldData : null);
+			mappedFieldData: _mappedFieldData.Count > 0 ? _mappedFieldData : null,
+			// ManagedPEBuilder otherwise uses a time-based id, changing bytes on every regeneration.
+			deterministicIdProvider: DeterministicContentId);
 		var peBlob = new BlobBuilder ();
 		peBuilder.Serialize (peBlob);
 		peBlob.WriteContentTo (stream);
 	}
 
+	static BlobContentId DeterministicContentId (IEnumerable<Blob> content)
+	{
+		using var hash = IncrementalHash.CreateHash (HashAlgorithmName.SHA256);
+		foreach (var blob in content) {
+			var segment = blob.GetBytes ();
+			if (segment.Count == 0) {
+				continue;
+			}
+			Debug.Assert (segment.Array is not null);
+			hash.AppendData (segment.Array, segment.Offset, segment.Count);
+		}
+		return BlobContentId.FromHash (hash.GetHashAndReset ());
+	}
+
 	/// <summary>
 	/// Adds (or retrieves from cache) an assembly reference.
 	/// </summary>

src/Microsoft.Android.Sdk.TrimmableTypeMap/ITrimmableTypeMapLogger.cs

@@ -13,6 +13,7 @@ public interface ITrimmableTypeMapLogger
 	void LogRootingManifestReferencedTypeInfo (string javaTypeName, string managedTypeName);
 	void LogManifestReferencedTypeNotFoundWarning (string javaTypeName);
 	void LogLibraryManifestMergeWarning (string message);
+	void LogInvalidManifestPlaceholderWarning (string placeholders);
 	void LogUnresolvableJavaPeerSkippedWarning (
 		string managedTypeName,
 		string assemblyName,

src/Microsoft.Android.Sdk.TrimmableTypeMap/Scanner/AssemblyIndex.cs

@@ -164,6 +164,7 @@ bool TryGetTypeReferenceAssemblyName (TypeReference typeReference, [NotNullWhen
 		// with the wrong AttributeName.
 		List<IntentFilterInfo>? intentFilters = null;
 		List<MetaDataInfo>? metaData = null;
+		Dictionary<string, object?>? layoutProperties = null;
 
 		foreach (var caHandle in typeDef.GetCustomAttributes ()) {
 			var ca = Reader.GetCustomAttribute (caHandle);
@@ -214,6 +215,8 @@ bool TryGetTypeReferenceAssemblyName (TypeReference typeReference, [NotNullWhen
 				metaData ??= new List<MetaDataInfo> ();
 				var (mdName, mdProps) = ParseNameAndProperties (ca);
 				metaData.Add (CreateMetaDataInfo (mdName, mdProps));
+			} else if (attrName == "LayoutAttribute") {
+				layoutProperties = ParseLayoutAttribute (ca);
 			} else if (attrInfo is null && ImplementsJniNameProviderAttribute (ca)) {
 				// Custom attribute implementing IJniNameProviderAttribute (e.g., user-defined [CustomJniName])
 				var name = TryGetNameProperty (ca);
@@ -232,6 +235,9 @@ bool TryGetTypeReferenceAssemblyName (TypeReference typeReference, [NotNullWhen
 			if (metaData is not null) {
 				attrInfo.MetaData.AddRange (metaData);
 			}
+			if (layoutProperties is not null) {
+				attrInfo.LayoutProperties = layoutProperties;
+			}
 		}
 
 		return (registerInfo, attrInfo);
@@ -425,6 +431,18 @@ RegisterInfo ParseRegisterInfo (CustomAttributeValue<string> value)
 		return null;
 	}
 
+	Dictionary<string, object?> ParseLayoutAttribute (CustomAttribute ca)
+	{
+		var value = DecodeAttribute (ca);
+		var properties = new Dictionary<string, object?> (StringComparer.Ordinal);
+		foreach (var named in value.NamedArguments) {
+			if (named.Name is not null) {
+				properties [named.Name] = named.Value;
+			}
+		}
+		return properties;
+	}
+
 	IntentFilterInfo ParseIntentFilterAttribute (CustomAttribute ca)
 	{
 		var value = DecodeAttribute (ca);
@@ -712,6 +730,12 @@ class TypeAttributeInfo (string attributeName)
 	/// Metadata entries declared on this type via [MetaData] attributes.
 	/// </summary>
 	public List<MetaDataInfo> MetaData { get; } = [];
+
+	/// <summary>
+	/// Named property values from a [Layout] attribute on this type, or null if none.
+	/// Maps to the &lt;layout&gt; child element of the component in the manifest.
+	/// </summary>
+	public Dictionary<string, object?>? LayoutProperties { get; set; }
 }
 
 sealed class ApplicationAttributeInfo () : TypeAttributeInfo ("ApplicationAttribute")

src/Microsoft.Android.Sdk.TrimmableTypeMap/Scanner/JavaPeerScanner.cs

@@ -274,6 +274,10 @@ static void ForceUnconditionalIfPresent (Dictionary<(string ManagedName, string
 		}
 	}
 
+	// ManagedPeer depends on reflection-based registration; the trimmable path uses IAndroidCallableWrapper.
+	static bool IsUnsupportedByTrimmableTypeMap (string managedFullName, string assemblyName) =>
+		managedFullName == "Java.Interop.ManagedPeer" && assemblyName == "Java.Interop";
+
 	void ScanAssembly (AssemblyIndex index, Dictionary<(string ManagedName, string AssemblyName), JavaPeerInfo> results)
 	{
 		foreach (var typeHandle in index.Reader.TypeDefinitions) {
@@ -286,6 +290,10 @@ void ScanAssembly (AssemblyIndex index, Dictionary<(string ManagedName, string A
 
 			var fullName = MetadataTypeNameResolver.GetFullName (typeDef, index.Reader);
 
+			if (IsUnsupportedByTrimmableTypeMap (fullName, index.AssemblyName)) {
+				continue;
+			}
+
 			// Temporarily allow [JniAddNativeMethodRegistrationAttribute] while we investigate
 			// which scenarios fail later in the trimmable typemap pipeline.
 			// if (index.MayUseJniAddNativeMethodRegistrationAttribute &&
@@ -2528,6 +2536,7 @@ void CollectExportField (MethodDefinition methodDef, AssemblyIndex index, List<J
 			Properties = attrInfo.Properties,
 			IntentFilters = attrInfo.IntentFilters,
 			MetaData = attrInfo.MetaData,
+			LayoutProperties = attrInfo.LayoutProperties,
 		};
 	}
 }

src/Microsoft.Android.Sdk.TrimmableTypeMap/TrimmableTypeMapGenerator.cs

@@ -155,6 +155,7 @@ GeneratedManifest GenerateManifest (List<JavaPeerInfo> allPeers, AssemblyManifes
 				// Other codes (e.g. unresolvable type properties) are not yet assigned XA codes
 				// and are intentionally not surfaced here.
 			},
+			WarnInvalidPlaceholder = placeholders => logger.LogInvalidManifestPlaceholderWarning (placeholders),
 			LibraryManifests = config.LibraryManifests ?? [],
 		};
 

src/Xamarin.Android.Build.Tasks/Tasks/GenerateTrimmableTypeMap.cs

@@ -46,6 +46,8 @@ public void LogManifestReferencedTypeNotFoundWarning (string javaTypeName) =>
 			log.LogCodedWarning ("XA4250", Properties.Resources.XA4250, javaTypeName);
 		public void LogLibraryManifestMergeWarning (string message) =>
 			log.LogCodedWarning ("XA4302", Properties.Resources.XA4302, message);
+		public void LogInvalidManifestPlaceholderWarning (string placeholders) =>
+			log.LogCodedWarning ("XA1010", Properties.Resources.XA1010, placeholders);
 		public void LogUnresolvableJavaPeerSkippedWarning (
 			string managedTypeName,
 			string assemblyName,

tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Generator/ManifestGeneratorTests.cs

@@ -105,6 +105,25 @@ public void Placeholders_AllValid_DoesNotWarn ()
 		Assert.Equal ("val1", (string?) doc.Root?.Element ("application")?.Attribute (AndroidNs + "label"));
 	}
 
+	[Fact]
+	public void Placeholders_EmptyKey_ReplacesEmptyTokenWithoutWarning ()
+	{
+		var gen = CreateDefaultGenerator ();
+		var warnings = new List<string> ();
+		gen.WarnInvalidPlaceholder = warnings.Add;
+		gen.ManifestPlaceholders = "=val1";
+		var template = ParseTemplate ("""
+			<?xml version="1.0" encoding="utf-8"?>
+			<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.app">
+			  <uses-sdk />
+			  <application android:label="${}" />
+			</manifest>
+			""");
+		var doc = GenerateAndLoad (gen, template: template);
+		Assert.Empty (warnings);
+		Assert.Equal ("val1", (string?) doc.Root?.Element ("application")?.Attribute (AndroidNs + "label"));
+	}
+
 	[Fact]
 	public void Package_PlaceholderToken_ReplacedWithResolvedPackageName ()
 	{
@@ -385,6 +404,24 @@ public void Activity_LayoutAttributeElement ()
 		Assert.Equal ("400dp", (string?)layout?.Attribute (AndroidNs + "minHeight"));
 	}
 
+	[Fact]
+	public void Service_LayoutAttributeElement_Ignored ()
+	{
+		var gen = CreateDefaultGenerator ();
+		var peer = CreatePeer ("com/example/app/MyService", new ComponentInfo {
+			Kind = ComponentKind.Service,
+			LayoutProperties = new Dictionary<string, object?> {
+				["DefaultWidth"] = "500dp",
+			},
+		});
+
+		var doc = GenerateAndLoad (gen, [peer]);
+		var service = doc.Root?.Element ("application")?.Element ("service");
+
+		Assert.NotNull (service);
+		Assert.Null (service?.Element ("layout"));
+	}
+
 	[Fact]
 	public void Activity_AllExtendedProperties ()
 	{