[TrimmableTypeMap] Add exception handling to UCO constructor callbacks (nctor_*_uco)

[Copilot]

UCO constructor callbacks (nctor_0_uco, nctor_1_uco, …) emitted by EmitUcoConstructor had no exception handling. An exception thrown by the activation constructor would cross the JNI boundary unhandled, causing a SIGABRT. This mirrors the same pattern already used by ManagedPeer.Construct.

Changes

PEAssemblyBuilder

• New EmitBody(…, Action<InstructionEncoder, ControlFlowBuilder>, …) overload — lets callers both emit IL and register exception regions (catch/finally) in a single pass.

TypeMapAssemblyEmitter

• New type refs: JniTransition, JniRuntime, System.Exception
• New member refs: JniEnvironment.BeginMarshalMethod, JniEnvironment.EndMarshalMethod, JniRuntime.OnUserUnhandledException
• EmitUcoConstructorBodyWithMarshal helper emits the standard marshal wrapper pattern:

// Generated nctor_0_uco — before
ldarg.0; ldarg.1; call get_WithinNewObjectScope; brtrue skip;
// ... activation ...
skip: ret

// Generated nctor_0_uco — after
ldarg.0; ldloca envp; ldloca runtime
call BeginMarshalMethod; brfalse done
.try {
    call get_WithinNewObjectScope; brtrue skip
    // ... activation ...
    skip: leave done
} catch (Exception) {
    stloc e; ldloc runtime; brfalse end
    ldloc runtime; ldloca envp; ldloc e
    callvirt OnUserUnhandledException
    end: leave done
} finally {
    ldloca envp; call EndMarshalMethod; endfinally
}
done: ret

• EmitUcoConstructor updated for both standard ((IntPtr, JniHandleOwnership)) and JavaInterop ((ref JniObjectReference, JniObjectReferenceOptions)) activation styles. Open-generic (no-op) UCO constructors are unchanged.
• New local variable encoding helpers (EncodeUcoConstructorLocals_Standard, _JavaInterop) for the expanded local layouts (JniTransition/JniRuntime/Exception + optional JniObjectReference).

Tests (TypeMapAssemblyGeneratorTests)

• 4 new tests verifying catch+finally exception regions are present in generated UCO constructor method bodies: standard leaf, JavaInterop, inherited ctor, and generic no-op.

[simonrozsival]

/review

[github-actions]

✅ Android PR Reviewer completed successfully!

[Copilot]

Pull request overview

This PR updates the TrimmableTypeMap generator so that generated UCO constructor callbacks (nctor_*_uco) wrap activation in the standard JniEnvironment.BeginMarshalMethod / EndMarshalMethod try/catch/finally pattern, preventing managed exceptions from crossing the JNI boundary and causing aborts.

Changes:

• Added a PEAssemblyBuilder.EmitBody overload that passes a ControlFlowBuilder to allow emitting IL and registering exception regions in one pass.
• Updated TypeMapAssemblyEmitter.EmitUcoConstructor to emit the marshal wrapper + catch/finally regions for both standard and JavaInterop activation styles.
• Added new tests verifying exception regions are present for non-generic UCO constructors and absent for open-generic no-op constructors.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Generator/TypeMapAssemblyGeneratorTests.cs	Adds tests asserting exception regions (catch+finally) for generated nctor_*_uco methods across activation styles and inheritance cases.
src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/TypeMapAssemblyEmitter.cs	Emits marshal-method wrapper (Begin/End + catch/finally) around UCO constructor activation and adds required type/member references and local signatures.
src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/PEAssemblyBuilder.cs	Introduces a new EmitBody overload that exposes ControlFlowBuilder so callers can register exception regions while emitting IL.

[github-actions]

✅ LGTM

Solid, well-structured change that fixes a real crash (SIGABRT from unhandled exceptions crossing the JNI boundary in UCO constructor callbacks). The implementation correctly mirrors the ManagedPeer.Construct marshal-method pattern.

What I verified:

• IL correctness: The exception region encoding follows ECMA-335 correctly — the finally region's try range [tryStart, finallyStart) properly encompasses both the try body and catch handler, so leave from either will trigger the finally.
• Early-return path: BeginMarshalMethod returning false branches to afterAll before tryStart, so no exception regions are entered — EndMarshalMethod is correctly skipped when no transition was started.
• Local variable layouts: Standard (3 locals) and JavaInterop (4 locals) signatures encode the correct types (valuetype for JniTransition/JniObjectReference, class for JniRuntime/Exception). Local indices in IL match the declared layouts.
• Null-safety in catch: The runtime null-check before callvirt OnUserUnhandledException correctly handles the case where BeginMarshalMethod returns true but runtime is null.
• Generic no-op: Open-generic UCO constructors are correctly left as simple ret stubs without exception handling.
• Tests: 4 tests covering all activation paths (standard leaf, JavaInterop, inherited ctor, generic no-op).
• CI: Public CI checks are green.

By severity:

	Count
💡 Suggestion	2

Two minor suggestions (missing invariant comment on the new EmitBody overload, and test helper extraction for repeated search pattern) — neither blocks merge.

Generated by Android PR Reviewer for issue #11178 · ● 4M

[simonrozsival]

CI failure unrelated:

Build_XAML_Change(False)
Exceeded expected time of 3000ms, actual 3119.268ms