[TrimmableTypeMap] Implement reflection-free TrimmableTypeMapValueManager and TrimmableTypeMapTypeManager by simonrozsival · Pull Request #11617 · dotnet/android

simonrozsival · 2026-06-09T21:34:41Z

Goal

Integrate the Java.Interop value-manager/type-manager split into dotnet/android while keeping the trimmable typemap runtime path reflection-free, AOT-friendly, and covered by targeted tests.

This PR is specifically about making the Android runtime use the new Java.Interop abstractions safely. Broader cleanup such as removing ManagedPeer support or changing NativeAOT runtime policy is intentionally left to follow-up PRs.

What changed

Java.Interop integration

Updated the Java.Interop submodule to the follow-up branch for [TrimmableTypeMap] Make adjustments to the base JniValueManager and JniTypeManager to make implementing the trimmable type map easier java-interop#1454.
The Java.Interop side now exposes only the minimal object-reference hook needed by JavaObjectArray<T>.SetElementAt():
- CreateLocalObjectReferenceArgument(Type type, object? value) returns an owned local JniObjectReference for element assignment. Callers must dispose the returned reference.
JavaObjectArray<T>.Clear() now directly writes Java null into each slot; it no longer needs value-manager or value-marshaler state.
Reflection-backed Java.Interop code still uses value marshalers internally: it creates marshaler state, copies out an independent local reference, then destroys the state immediately.
The trimmable Android path does not implement or use GetValueMarshaler*() for JavaObjectArray<T> element assignment.

Runtime manager wiring

Switched legacy Mono/CoreCLR Android managers to the Java.Interop ReflectionJniTypeManager / ReflectionJniValueManager base implementations.
Added a CoreCLR Android value manager that preserves Android peer registration, GC bridge tracking, activation, and exception unboxing behavior.
Added trimmable typemap value/type managers for generated-typemap mode:
- TrimmableTypeMapTypeManager resolves generated proxy/type-map data without reflection fallback.
- TrimmableTypeMapValueManager constructs and marshals generated peers without the reflection-backed value manager.
- Primitive arrays, Java arrays, peerables, proxies, strings, primitive wrappers, and general JavaConvert fallback cases are handled without reflection fallback.
Split the large JavaMarshalValueManager.cs implementation into per-type files.
Removed the old SimpleValueManager path.

Trimmable typemap build fixes

Preserved Microsoft.Android.Runtime.ManagedTypeMapping for linker/type-map steps that still need it.
Fixed post-trim Java source/stamp paths for multi-RID CoreCLR builds so RID-specific outputs do not collide or leave stale Java sources behind.
Kept [JniAddNativeMethodRegistrationAttribute] diagnostics focused on user assemblies; framework/runtime internal users are handled by generated replacements or intentionally unsupported runtime paths.
Removed the unproven RequiresUnreferencedCode annotation from ExportFieldAttribute. [ExportField] is handled by generated trimmable type-map code and does not need to warn simply for constructing the attribute.

Test strategy

Trimmable runtime tests exclude TrimmableTypeMapUnsupported via test categories.
ManagedPeer-dependent Java.Interop desktop fixture tests remain skipped by category in the trimmable Android lane. This PR does not add Android-local fixture workarounds for those tests; ManagedPeer removal/porting is left to follow-up work.
Reflection-manager-only Java.Interop tests remain covered by Java.Interop's standalone test suite; the Android trimmable lane uses generated managers.
Added/updated host-side tests for:
- scanner XA4251 behavior,
- trimmable runtimeconfig switches,
- post-trim Java source generation,
- [Export] / [ExportField] trimmable codegen,
- trim-warning filtering for generated type-map code.

Review notes / intentional non-goals

NativeAOT runtime policy is not broadened in this PR; non-trimmable NativeAOT behavior is left unchanged for a separate PR.
ManagedPeer removal is not part of this PR. ManagedPeer-dependent tests are categorized unsupported rather than worked around locally.
Java.Interop value marshalers remain implementation detail for reflection-backed Java.Interop behavior; trimmable Android code uses generated managers and direct local object-reference creation.
The built-in Type → JniTypeSignature mapping intentionally keeps the current Type.GetTypeCode + explicit nullable typeof checks. Benchmarking showed Nullable.GetUnderlyingType() allocates and should not be used on this path.

Local validation

Validated locally on this branch with:

dotnet build external/Java.Interop/src/Java.Interop/Java.Interop.csproj \
  -p:Configuration=Debug \
  -m:1 \
  -nodeReuse:false \
  --no-restore \
  -v:minimal

dotnet test tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests.csproj \
  -v minimal \
  --no-restore

Results:

Java.Interop build passed.
Trimmable typemap tests passed (562 passed).
dotnet build src/Mono.Android/Mono.Android.csproj -p:Configuration=Debug -p:AndroidSdkDirectory=/Users/simonrozsival/android-toolchain/sdk -m:1 -nodeReuse:false --no-restore -v:minimal compiled Mono.Android.Runtime.dll; the remaining local failure is Android SDK provisioning (extras/android/m2repository.staging and docs.staging missing), not C# or trim-analyzer errors.

simonrozsival · 2026-06-09T21:34:58Z

/azp run

azure-pipelines · 2026-06-09T21:35:08Z

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simonrozsival · 2026-06-10T06:17:46Z

Rebased onto #11622 (external/Java.Interop d7dbad5) and revalidated targeted Mono.Android build locally.\n\n/azp run

simonrozsival · 2026-06-11T08:51:54Z

/azp run

azure-pipelines · 2026-06-11T08:52:00Z

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simonrozsival · 2026-06-11T08:52:20Z

/azp run

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simonrozsival · 2026-06-11T10:14:18Z

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Bumps [external/Java.Interop](https://github.com/dotnet/java-interop) from `b881d21` to `d7dbad5`. - [Commits](dotnet/java-interop@b881d21...d7dbad5) --- updated-dependencies: - dependency-name: external/Java.Interop dependency-version: d7dbad5e30a8f03743a508a95c4e9159fe1f6607 dependency-type: direct:production ... Signed-off-by: dependabot[bot] <support@github.com>

Split the Android JavaMarshal value manager into CoreCLR and trimmable implementations that share peer registration and GC bridge integration through a reusable helper. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Keep the trimmable typemap value manager on the abstract JniValueManager base, sharing only peer registration and GC bridge state with the CoreCLR value manager. Leave value marshaling unsupported for now until Android has trimmable-specific marshalers. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Move TrimmableTypeMapTypeManager off ReflectionJniTypeManager and implement type lookup through explicit built-in mappings plus the generated trimmable typemap. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Remove newly added UnconditionalSuppressMessage attributes, propagate Requires annotations from reflection-backed managers, and carry DAM annotations through JavaPeerProxy/TrimmableTypeMap target type metadata. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Replace newly added suppressions on reflection-backed managers with RequiresUnreferencedCode and RequiresDynamicCode propagation. Leave trimmable value/type managers free of UnconditionalSuppressMessage attributes. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Replace remaining UnconditionalSuppressMessage attributes in the reflection-backed Android manager implementations with RequiresUnreferencedCode/RequiresDynamicCode where appropriate. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Replace invoker lookup and legacy TypeManager peer creation suppressions with RequiresUnreferencedCode/RequiresDynamicCode propagation. Keep GetObject suppression because adding DAM there breaks delegate/reflection table use sites. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Annotate runtime feature switches with FeatureGuard and structure manager factory branches so reflection-backed manager creation is guarded by the relevant runtime feature instead of broad Requires annotations on the factory methods. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Remove the single-use JavaMarshalReflectionValueManagerBase and keep the shared peer/GC bridge state in JavaMarshalPeerManager, directly delegated by the CoreCLR value manager. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Make both TrimmableTypeMapTypeManager RegisterNativeMembers overloads throw UnreachableException directly. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Make unused trimmable JniTypeManager paths fail loudly, remove ManagedPeer from trimmable runtime artifacts, and add an initial AOT-safe value-marshaling implementation for the trimmable value manager. Update tests and trimmable runtime coverage to use feature switches via AppContext and enable the value-marshaling test bucket for follow-up triage. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Use the Java.Interop proxy and peerable value marshalers from the trimmable value manager instead of duplicating peerable marshaling locally. This also updates the Java.Interop submodule to the follow-up branch with the shared proxy marshaler and re-enables the trimmable tests now covered by the shared marshalers. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Handle Java peerable elements and Java primitive array wrappers without reflection in the trimmable value manager. This lets JavaObjectArray<JavaObject> preserve peer identity and JavaObjectArray<JavaInt32Array> create and read int-array elements correctly. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

azure-pipelines · 2026-06-12T11:09:09Z

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Add Android trimmable RenameClass fixture variants without ManagedPeer.construct so JniPeerMembersTests.ReplacementTypeUsedForMethodLookup can exercise replacement-type method lookup on device. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

simonrozsival · 2026-06-12T11:19:03Z

/azp run

azure-pipelines · 2026-06-12T11:19:13Z

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Add Android trimmable CallNonvirtual fixture variants without ManagedPeer.construct so MethodBindingTests can validate virtual dispatch behavior under the trimmable typemap. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

simonrozsival · 2026-06-12T11:24:32Z

/azp run

azure-pipelines · 2026-06-12T11:24:42Z

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Use the existing InnerException member directly in throwable unwrapping paths instead of adding a redundant Exception property. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

simonrozsival · 2026-06-12T11:33:15Z

/azp run

azure-pipelines · 2026-06-12T11:33:24Z

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simonrozsival · 2026-06-12T11:41:50Z

/azp run

azure-pipelines · 2026-06-12T11:41:59Z

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Keep the PR focused by reverting NativeAOT manager wiring and ManagedTypeManager cleanup, removing Android-local ManagedPeer fixture replacements, and dropping ManagedPeer absence assertions. Unsupported ManagedPeer-dependent Java.Interop tests remain skipped by category. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

simonrozsival · 2026-06-12T12:03:53Z

/azp run

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Record the benchmark finding that the current Type.GetTypeCode plus explicit nullable checks path is zero-allocation, and avoid Nullable.GetUnderlyingType because it allocates. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

simonrozsival · 2026-06-12T12:16:46Z

/azp run

azure-pipelines · 2026-06-12T12:16:57Z

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Move each top-level Java marshal value manager type into its own source file and route JavaObjectArray state creation through JniValueManager so the trimmable path no longer needs a value-marshaler implementation. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Remove unused trimmable value-marshaler helper code and keep only the object-reference state path needed for JavaObjectArray element assignment. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

simonrozsival · 2026-06-12T15:09:22Z

/azp run

azure-pipelines · 2026-06-12T15:09:32Z

Azure Pipelines successfully started running 1 pipeline(s).

Update the trimmable value manager to return standalone local JNI references for JavaObjectArray element assignment and remove the remaining marshaler-state cleanup path. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

simonrozsival · 2026-06-12T16:38:34Z

/azp run

azure-pipelines · 2026-06-12T16:38:44Z

Azure Pipelines successfully started running 1 pipeline(s).

Update the trimmable value manager override to match the CreateLocalObjectReferenceArgument naming from Java.Interop. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

simonrozsival · 2026-06-12T16:54:39Z

/azp run

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simonrozsival force-pushed the dev/simonrozsival/java-interop-1441-android branch from 42a1b8e to 47450cf Compare June 10, 2026 06:17

simonrozsival changed the base branch from main to dependabot/submodules/external/Java.Interop-d7dbad5 June 10, 2026 07:11

simonrozsival changed the base branch from dependabot/submodules/external/Java.Interop-d7dbad5 to main June 11, 2026 10:15

dependabot Bot and others added 18 commits June 11, 2026 12:15

Use pure trimmable typemap type manager

01dfd04

Move TrimmableTypeMapTypeManager off ReflectionJniTypeManager and implement type lookup through explicit built-in mappings plus the generated trimmable typemap. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Throw unreachable from trimmable native registration

6a8ec68

Make both TrimmableTypeMapTypeManager RegisterNativeMembers overloads throw UnreachableException directly. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Remove SimpleValueManager

7d3d1e3

Simplify changes to the ManagedTypeManager

725d433

Remove the option to use ManagedTypeManager

caaea85

Cleanup value managers

b489d1f

Re-enable trimmable method binding coverage

7ab9659

Add Android trimmable CallNonvirtual fixture variants without ManagedPeer.construct so MethodBindingTests can validate virtual dispatch behavior under the trimmable typemap. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Remove JavaProxyThrowable Exception wrapper

12946a7

Use the existing InnerException member directly in throwable unwrapping paths instead of adding a redundant Exception property. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

simonrozsival changed the title ~~Use Java.Interop value manager split in Android~~ [TrimmableTypeMap] Implement reflection-free TrimmableTypeMapValueManager and TrimmableTypeMapTypeManager Jun 12, 2026

simonrozsival mentioned this pull request Jun 12, 2026

[TrimmableTypeMap] Make adjustments to the base JniValueManager and JniTypeManager to make implementing the trimmable type map easier dotnet/java-interop#1454

Open

simonrozsival and others added 2 commits June 12, 2026 15:17

Simplify trimmable object array marshaling

a5b39d1

Remove unused trimmable value-marshaler helper code and keep only the object-reference state path needed for JavaObjectArray element assignment. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Clarify trimmable local reference ownership

f928f99

Update the trimmable value manager override to match the CreateLocalObjectReferenceArgument naming from Java.Interop. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Goal

What changed

Java.Interop integration

Runtime manager wiring

Trimmable typemap build fixes

Test strategy

Review notes / intentional non-goals

Local validation

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