[TrimmableTypeMap] Java peer scanner core

eng/Versions.props

@@ -16,6 +16,7 @@
     <MicrosoftTemplateEngineAuthoringTasksPackageVersion>11.0.100-preview.1.26076.102</MicrosoftTemplateEngineAuthoringTasksPackageVersion>
     <MicrosoftDotNetCecilPackageVersion>0.11.5-preview.26076.102</MicrosoftDotNetCecilPackageVersion>
     <SystemIOHashingPackageVersion>9.0.4</SystemIOHashingPackageVersion>
+    <SystemReflectionMetadataPackageVersion>11.0.0-preview.1.26104.118</SystemReflectionMetadataPackageVersion>
     <!-- Previous .NET Android version -->
     <MicrosoftNETSdkAndroidManifest100100PackageVersion>36.1.30</MicrosoftNETSdkAndroidManifest100100PackageVersion>
     <AndroidNetPreviousVersion>$(MicrosoftNETSdkAndroidManifest100100PackageVersion)</AndroidNetPreviousVersion>

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

@@ -0,0 +1,23 @@
+// Polyfills for C# language features on netstandard2.0
+
+// Required for init-only setters
+namespace System.Runtime.CompilerServices
+{
+	static class IsExternalInit { }
+
+	[AttributeUsage (AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = false, Inherited = false)]
+	sealed class RequiredMemberAttribute : Attribute { }
+
+	[AttributeUsage (AttributeTargets.All, AllowMultiple = true, Inherited = false)]
+	sealed class CompilerFeatureRequiredAttribute (string featureName) : Attribute
+	{
+		public string FeatureName { get; } = featureName;
+		public bool IsOptional { get; init; }
+	}
+}
+
+namespace System.Diagnostics.CodeAnalysis
+{
+	[AttributeUsage (AttributeTargets.Constructor, AllowMultiple = false, Inherited = false)]
+	sealed class SetsRequiredMembersAttribute : Attribute { }
+}

src/Microsoft.Android.Sdk.TrimmableTypeMap/Microsoft.Android.Sdk.TrimmableTypeMap.csproj

@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <Import Project="..\..\Configuration.props" />
+
+  <PropertyGroup>
+    <TargetFramework>$(TargetFrameworkNETStandard)</TargetFramework>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
+    <RootNamespace>Microsoft.Android.Sdk.TrimmableTypeMap</RootNamespace>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="System.IO.Hashing" Version="$(SystemIOHashingPackageVersion)" />
+    <PackageReference Include="System.Reflection.Metadata" Version="$(SystemReflectionMetadataPackageVersion)" />
+  </ItemGroup>
+
+</Project>

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

@@ -0,0 +1,265 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Reflection.Metadata;
+using System.Reflection.PortableExecutable;
+
+namespace Microsoft.Android.Sdk.TrimmableTypeMap;
+
+/// <summary>
+/// Phase 1 index for a single assembly. Built in one pass over TypeDefinitions,
+/// all subsequent lookups are O(1) dictionary lookups.
+/// </summary>
+sealed class AssemblyIndex : IDisposable
+{
+	readonly PEReader peReader;
+	internal readonly CustomAttributeTypeProvider customAttributeTypeProvider;
+
+	public MetadataReader Reader { get; }
+	public string AssemblyName { get; }
+	public string FilePath { get; }
+
+	/// <summary>
+	/// Maps full managed type name (e.g., "Android.App.Activity") to its TypeDefinitionHandle.
+	/// </summary>
+	public Dictionary<string, TypeDefinitionHandle> TypesByFullName { get; } = new (StringComparer.Ordinal);
+
+	/// <summary>
+	/// Cached [Register] attribute data per type.
+	/// </summary>
+	public Dictionary<TypeDefinitionHandle, RegisterInfo> RegisterInfoByType { get; } = new ();
+
+	/// <summary>
+	/// All custom attribute data per type, pre-parsed for the attributes we care about.
+	/// </summary>
+	public Dictionary<TypeDefinitionHandle, TypeAttributeInfo> AttributesByType { get; } = new ();
+
+	AssemblyIndex (PEReader peReader, MetadataReader reader, string assemblyName, string filePath)
+	{
+		this.peReader = peReader;
+		this.customAttributeTypeProvider = new CustomAttributeTypeProvider (reader);
+		Reader = reader;
+		AssemblyName = assemblyName;
+		FilePath = filePath;
+	}
+
+	public static AssemblyIndex Create (string filePath)
+	{
+		var peReader = new PEReader (File.OpenRead (filePath));
+		var reader = peReader.GetMetadataReader ();
+		var assemblyName = reader.GetString (reader.GetAssemblyDefinition ().Name);
+		var index = new AssemblyIndex (peReader, reader, assemblyName, filePath);
+		index.Build ();
+		return index;
+	}
+
+	void Build ()
+	{
+		foreach (var typeHandle in Reader.TypeDefinitions) {
+			var typeDef = Reader.GetTypeDefinition (typeHandle);
+
+			var fullName = MetadataTypeNameResolver.GetFullName (typeDef, Reader);
+			if (fullName.Length == 0) {
+				continue;
+			}
+
+			TypesByFullName [fullName] = typeHandle;
+
+			var (registerInfo, attrInfo) = ParseAttributes (typeDef);
+
+			if (attrInfo is not null) {
+				AttributesByType [typeHandle] = attrInfo;
+			}
+
+			if (registerInfo is not null) {
+				RegisterInfoByType [typeHandle] = registerInfo;
+			}
+		}
+	}
+
+	(RegisterInfo? register, TypeAttributeInfo? attrs) ParseAttributes (TypeDefinition typeDef)
+	{
+		RegisterInfo? registerInfo = null;
+		TypeAttributeInfo? attrInfo = null;
+
+		foreach (var caHandle in typeDef.GetCustomAttributes ()) {
+			var ca = Reader.GetCustomAttribute (caHandle);
+			var attrName = GetCustomAttributeName (ca, Reader);
+
+			if (attrName is null) {
+				continue;
+			}
+
+			if (attrName == "RegisterAttribute") {
+				registerInfo = ParseRegisterAttribute (ca, customAttributeTypeProvider);
+			} else if (attrName == "ExportAttribute") {
+				// [Export] is a method-level attribute; it is parsed at scan time by JavaPeerScanner
+			} else if (IsKnownComponentAttribute (attrName)) {
+				attrInfo ??= CreateTypeAttributeInfo (attrName);
+				var componentName = TryGetNameProperty (ca);
+				if (componentName is not null) {
+					attrInfo.JniName = componentName.Replace ('.', '/');
+				}
+				if (attrInfo is ApplicationAttributeInfo applicationAttributeInfo) {
+					applicationAttributeInfo.BackupAgent = TryGetTypeProperty (ca, "BackupAgent");
+					applicationAttributeInfo.ManageSpaceActivity = TryGetTypeProperty (ca, "ManageSpaceActivity");
+				}
+			}
+		}
+
+		return (registerInfo, attrInfo);
+	}
+
+	static readonly HashSet<string> KnownComponentAttributes = new (StringComparer.Ordinal) {
+		"ActivityAttribute",
+		"ServiceAttribute",
+		"BroadcastReceiverAttribute",
+		"ContentProviderAttribute",
+		"ApplicationAttribute",
+		"InstrumentationAttribute",
+	};
+
+	static TypeAttributeInfo CreateTypeAttributeInfo (string attrName)
+	{
+		return attrName == "ApplicationAttribute"
+			? new ApplicationAttributeInfo ()
+			: new TypeAttributeInfo (attrName);
+	}
+
+	static bool IsKnownComponentAttribute (string attrName) => KnownComponentAttributes.Contains (attrName);
+
+	internal static string? GetCustomAttributeName (CustomAttribute ca, MetadataReader reader)
+	{
+		if (ca.Constructor.Kind == HandleKind.MemberReference) {
+			var memberRef = reader.GetMemberReference ((MemberReferenceHandle)ca.Constructor);
+			if (memberRef.Parent.Kind == HandleKind.TypeReference) {
+				var typeRef = reader.GetTypeReference ((TypeReferenceHandle)memberRef.Parent);
+				return reader.GetString (typeRef.Name);
+			}
+		} else if (ca.Constructor.Kind == HandleKind.MethodDefinition) {
+			var methodDef = reader.GetMethodDefinition ((MethodDefinitionHandle)ca.Constructor);
+			var declaringType = reader.GetTypeDefinition (methodDef.GetDeclaringType ());
+			return reader.GetString (declaringType.Name);
+		}
+		return null;
+	}
+
+	internal static RegisterInfo ParseRegisterAttribute (CustomAttribute ca, ICustomAttributeTypeProvider<string> provider)
+	{
+		var value = ca.DecodeValue (provider);
+
+		string jniName = "";
+		string? signature = null;
+		string? connector = null;
+		bool doNotGenerateAcw = false;
+
+		if (value.FixedArguments.Length > 0) {
+			jniName = (string?)value.FixedArguments [0].Value ?? "";
+		}
+		if (value.FixedArguments.Length > 1) {
+			signature = (string?)value.FixedArguments [1].Value;
+		}
+		if (value.FixedArguments.Length > 2) {
+			connector = (string?)value.FixedArguments [2].Value;
+		}
+
+		if (TryGetNamedBooleanArgument (value, "DoNotGenerateAcw", out var doNotGenerateAcwValue)) {
+			doNotGenerateAcw = doNotGenerateAcwValue;
+		}
+
+		return new RegisterInfo {
+			JniName = jniName,
+			Signature = signature,
+			Connector = connector,
+			DoNotGenerateAcw = doNotGenerateAcw,
+		};
+	}
+
+	string? TryGetTypeProperty (CustomAttribute ca, string propertyName)
+	{
+		var value = ca.DecodeValue (customAttributeTypeProvider);
+		var typeName = TryGetNamedArgument<string> (value, propertyName);
+		if (!string.IsNullOrEmpty (typeName)) {
+			return typeName;
+		}
+		return null;
+	}
+
+	string? TryGetNameProperty (CustomAttribute ca)
+	{
+		var value = ca.DecodeValue (customAttributeTypeProvider);
+
+		// Check named arguments first (e.g., [Activity(Name = "...")])
+		var name = TryGetNamedArgument<string> (value, "Name");
+		if (!string.IsNullOrEmpty (name)) {
+			return name;
+		}
+
+		// Fall back to first constructor argument (e.g., [CustomJniName("...")])
+		if (value.FixedArguments.Length > 0 && value.FixedArguments [0].Value is string ctorName && !string.IsNullOrEmpty (ctorName)) {
+			return ctorName;
+		}
+
+		return null;
+	}
+
+	static T? TryGetNamedArgument<T> (CustomAttributeValue<string> value, string argumentName) where T : class
+	{
+		foreach (var named in value.NamedArguments) {
+			if (named.Name == argumentName && named.Value is T typedValue) {
+				return typedValue;
+			}
+		}
+		return null;
+	}
+
+	static bool TryGetNamedBooleanArgument (CustomAttributeValue<string> value, string argumentName, out bool argumentValue)
+	{
+		foreach (var named in value.NamedArguments) {
+			if (named.Name == argumentName && named.Value is bool boolValue) {
+				argumentValue = boolValue;
+				return true;
+			}
+		}
+
+		argumentValue = false;
+		return false;
+	}
+
+	public void Dispose ()
+	{
+		peReader.Dispose ();
+	}
+}
+
+/// <summary>
+/// Parsed [Register] attribute data for a type or method.
+/// </summary>
+sealed record RegisterInfo
+{
+	public required string JniName { get; init; }
+	public string? Signature { get; init; }
+	public string? Connector { get; init; }
+	public bool DoNotGenerateAcw { get; init; }
+}
+
+/// <summary>
+/// Parsed [Export] attribute data for a method.
+/// </summary>
+sealed record ExportInfo
+{
+	public IReadOnlyList<string>? ThrownNames { get; init; }
+	public string? SuperArgumentsString { get; init; }
+}
+
+class TypeAttributeInfo (string attributeName)
+{
+	public string AttributeName { get; } = attributeName;
+	public string? JniName { get; set; }
+}
+
+sealed class ApplicationAttributeInfo () : TypeAttributeInfo ("ApplicationAttribute")
+{
+	public string? BackupAgent { get; set; }
+	public string? ManageSpaceActivity { get; set; }
+}