[TrimmableTypeMap] Add UCO wrappers, JCW generator, and JNI signature helpers

[simonrozsival]

Closes #10799

Summary

Adds UCO (UnifiedCallableObject) wrapper generation, JCW (Java Callable Wrapper) Java source generation, and JNI signature parsing utilities on top of the TypeMap proxy groundwork from PR #10808.

Generator additions

• JcwJavaSourceGenerator — generates .java source files for each ACW type with registerNatives in static {} blocks, native method declarations, constructor chains with super() calls, and @Override annotations
• JniSignatureHelper — JNI signature parsing (parameter types, return types, JNI↔Java type conversion, CLR type encoding for IL emission)
• ModelBuilder — extended with UCO method/constructor building, native registration data, and isAcw classification
• TypeMapAssemblyEmitter — extended with EmitUcoMethod (UnmanagedCallersOnly wrappers that delegate to n_* callbacks), EmitUcoConstructor, EmitRegisterNatives (JNI native method registration), and IAndroidCallableWrapper interface implementation for ACW proxy types

Scanner enrichment

• JavaPeerInfo — added BaseJavaName, ImplementedInterfaceJavaNames, JavaConstructors, JniParameterInfo, ThrownNames for downstream generators
• JavaPeerScanner — resolver methods for base types, interfaces, constructors; fixed NativeCallbackName for constructors (n_ctor instead of invalid n_.ctor)

Model additions

• UcoMethodData / UcoConstructorData — describe UnmanagedCallersOnly wrappers to emit
• NativeRegistrationData — JNI native method registrations for RegisterNatives

Tests

• 215 tests covering all generators, model builder scenarios, scanner behavior, and edge cases
• Test fixtures extended with ExportWithThrows type
• Stream-based test helpers avoid disk I/O for faster, more reliable tests

Follow-up work

• GetContainerFactory() — moved to [TrimmableTypeMap] Implement TypeManager and ValueManager and other Runtime code #10791 (runtime issue); will emit the method body once JavaPeerContainerFactory is defined
• MSBuild task integration (_GenerateJavaStubs decomposition) — tracked in [TrimmableTypeMap] Decompose _GenerateJavaStubs: shared tasks for trimmable path #10807
• Implementor/EventDispatcher trimming optimization — tracked in [TrimmableTypeMap] Explore trimming optimization for Implementor and EventDispatcher types #10911

Note on GetFunctionPointer

The issue spec mentioned GetFunctionPointer(int) as an alternative dispatch mechanism. Since we use RegisterNatives (which binds JNI native methods to UCO wrappers at class load time), GetFunctionPointer is not needed.

[simonrozsival]

🤖 AI Review Summary

Verdict: ✅ LGTM

Found 0 issues.

Reviewed all 17 changed files against 14 rule categories. Read full source files (not just diff) to understand invariants and call patterns.

Checked and verified:

• No null-forgiving !, no Array.Empty<T>() in new code, no string.Empty, no #nullable enable, no empty catch blocks
• JNI boolean correctly encoded as byte (blittable for [UnmanagedCallersOnly])
• JI-style activation preserved from #10808 (JniObjectReference conversion + JNIEnv.DeleteRef cleanup)
• Content-dependent deterministic MVID (ComputeContentFingerprint)
• Proxy name collision guard (usedProxyNames)
• Implementor/EventDispatcher trimmability heuristic with documented trade-off
• Input validation on all public methods; internal Generate(type, writer) has single call site with pre-validated args
• No resource leaks — all IDisposable properly managed

👍 Clean scanner → model → emitter pipeline. UCO wrappers, JCW Java source, and JNI signature parsing integrate well with the #10808 proxy groundwork. 219 tests with good edge-case coverage and stream-based helpers.

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Review generated by android-reviewer from review guidelines.

[simonrozsival]

@jonathanpeppers this is ready for review. Adds UCO wrappers, JCW Java source generator, and JNI signature helpers on top of #10808.

[Copilot]

Pull request overview

Adds TypeMap generator support for ACW scenarios by emitting UCO (UnmanagedCallersOnly) wrapper methods, JNI RegisterNatives registration, a JCW .java source generator, and shared JNI signature parsing helpers—building on the existing TrimmableTypeMap scanner/model/emitter pipeline.

Changes:

• Extend scanning/model/emission pipeline to represent and emit ACW-specific data (constructors, UCO wrappers, native registrations, RegisterNatives).
• Add JcwJavaSourceGenerator and JniSignatureHelper for generating Java stubs and parsing JNI signatures/types.
• Expand/adjust tests and fixtures to cover UCO wrappers, native registration, JNI signature parsing, and throws clauses.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/TestFixtures/TestTypes.cs	Adds ExportWithThrows fixture type used to validate throws clause generation.
tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/TestFixtures/StubAttributes.cs	Extends ExportAttribute stub with ThrownNames to support fixture scanning/tests.
tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Generator/TypeMapModelBuilderTests.cs	Adds model-level tests for ACW classification, UCO wrapper/ctor generation, and native registrations.
tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Generator/TypeMapAssemblyGeneratorTests.cs	Adds PE metadata tests verifying RegisterNatives and UCO-related metadata presence.
tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Generator/RootTypeMapAssemblyGeneratorTests.cs	Updates root generator tests for empty and multi-target cases.
tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Generator/JcwJavaSourceGeneratorTests.cs	New tests covering JCW Java output structure, signatures, filtering, and throws clauses.
tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Generator/FixtureTestBase.cs	Enhances fixture helpers for ACW peers and adds temp directory helpers for file-based JCW tests.
src/Microsoft.Android.Sdk.TrimmableTypeMap/Scanner/JavaPeerScanner.cs	Adds constructor extraction and fixes native callback naming for constructors.
src/Microsoft.Android.Sdk.TrimmableTypeMap/Scanner/JavaPeerInfo.cs	Enriches scanned model with constructors and additional marshal/native metadata.
src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/TypeMapAssemblyEmitter.cs	Emits UCO wrappers, RegisterNatives, and ACW proxy interface implementation.
src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/ModelBuilder.cs	Builds ACW/UCO/native-registration model data and tracks cross-assembly callback dependencies.
src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/Model/TypeMapAssemblyData.cs	Adds model records for UCO methods/ctors and native registrations, plus IsAcw proxy flag.
src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/JniSignatureHelper.cs	New helper for parsing JNI signatures and mapping to CLR/Java types, plus JNI name validation.
src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/JcwJavaSourceGenerator.cs	New generator producing JCW .java files for ACW types based on scanned JavaPeerInfo.

[simonrozsival]

Re: the two unresolved review comments:

IAndroidCallableWrapper assembly reference — This type doesn't exist yet; it will be defined when we implement the runtime side. The assembly placement (Mono.Android vs Java.Interop) is a design decision we'll make at that point. This reference was already present in PR #10808 (on main) with the same MonoAndroidRef. We'll fix it to match whichever assembly the type lands in.

Nullable after Assert.NotNull — This is main's existing test code (the Fixture_HelperType_IsUnconditional test). xUnit's Assert.NotNull has [NotNull] annotation which the compiler respects — the project builds with <WarningsAsErrors>Nullable</WarningsAsErrors> and produces no warnings here.

[simonrozsival]

🤖 AI Review Summary

Verdict: ⚠️ Needs Changes

Found 3 issues: 1 warning and 2 suggestions. CI is still pending (build 1332295).

• ⚠️ Error handling: Empty catch block swallows IOException silently in DeleteTempDir (FixtureTestBase.cs:141)
• 💡 Formatting: Missing newline at end of file in JcwJavaSourceGeneratorTests.cs, TypeMapAssemblyGeneratorTests.cs, and TypeMapModelBuilderTests.cs
• 💡 Testing: ClassDeclaration, AbstractType, and NestedType tests use Assert.Contains("...\n", java) while the 5 analogous failing tests use AssertContainsLine. These happen to work because they assert writer.Write($"...\n") output (not raw strings), but consider using AssertContainsLine throughout for consistency

👍 Excellent test coverage — 215 tests covering all generators, model builder, scanner, and edge cases. The JNI validation in ValidateJniName properly prevents path traversal. The UCO/RegisterNatives emission architecture is well-documented with clear XML docs and a helpful pseudo-Java example in the class remarks. The AssertContainsLine helper is a clean fix for the cross-platform newline issue. Good use of record types for data models.

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Review generated by android-reviewer from review guidelines.

[simonrozsival]

🤖 AI Review Summary (v3)

Verdict: ⚠️ Needs Changes

All previous findings have been addressed. No new code issues found.

• ⚠️ CI: All legs are pending (build 1332407). The previous run's Linux failure (CS0246: AdbDeviceInfo) was a pre-existing main issue from the xamarin-android-tools submodule bump — not caused by this PR. Cannot confirm merge readiness until CI is green.

👍 Clean diff: no null!, no empty catch blocks, no Array.Empty, no disk IO in tests, all files end with newlines. AssertContainsLine properly handles cross-platform line endings. 214 tests cover generators, model builder, scanner, and edge cases.

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Review generated by android-reviewer from review guidelines.