[r8-obfuscation] Enable R8 JNI name obfuscation for CoreCLR - #12632

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simonrozsival-trimmable-typemap-jni-rewritingfrom

simonrozsival-coreclr-r8-jni-integration

simonrozsival commented Sep 1, 2026 •

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Related to #12535

Depends on #12631

Layer 5 of 6 in the replacement stack for #12575. This layer adds the shared two-pass R8 seed/final mapping machinery and enables opt-in JNI name obfuscation for trimmed CoreCLR builds. NativeAOT support follows in layer 6.

Testing:

Parsed all modified MSBuild targets and resources as XML.
Built Xamarin.Android.Build.Tasks.csproj and the complete Xamarin.Android.Build.Tests.csproj.
Passed all 35 focused GenerateProguardConfiguration/R8 task tests, including canonical LF manifest output for the Windows failure in build 1577218.
Attempted all three CoreCLR integration tests; the local environment blocked project restore with NETSDK1147 because the unrelated wasm-tools workload is not installed.

simonrozsival force-pushed the simonrozsival-coreclr-r8-jni-integration branch from bdfec0a to 7c15701 Compare

September 1, 2026 19:34

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[r8-obfuscation] Enable R8 JNI name obfuscation for NativeAOT #12634

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September 1, 2026 22:33

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/azp run

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/azp run

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Azure Pipelines will not run the associated pipelines, because the pull request was updated after the run command was issued. Review the pull request again and issue a new run command.

simonrozsival force-pushed the simonrozsival-coreclr-r8-jni-integration branch from 1cee050 to 65740e9 Compare

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simonrozsival force-pushed the simonrozsival-coreclr-r8-jni-integration branch from 60b031c to 15c4b79 Compare

September 2, 2026 21:34

simonrozsival and others added 18 commits

September 3, 2026 07:00


          Complete managed JNI rewrite coverage

afe9106

Preserve managed constructor spellings, resolve cached static JNI class handles through proven FindClass assignments, warn on unsafe renamed lookup sources, and skip identity string rewrites.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Address managed JNI rewrite review feedback

7fbf20a

Use platform-aware path identity for in-place rewrites, validate custom attribute prologs, and diagnose unsafe member-only mappings without polluting rewrite manifests or reverse scans.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Rewrite trimmable typemap JNI metadata

a507655

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Handle shared FieldRVA names conservatively

520236a

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Avoid sharing owner-specific JNI method names

3eeeaaa

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          [r8-obfuscation] Enable R8 JNI name obfuscation for CoreCLR

be9f396

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Fix R8 JNI obfuscation integration

dbec950

Allow seed R8 to rename ACWs, track final R8 generated inputs, and keep validation mappings private when public mapping output is disabled.

Use canonical LF expectations for generated reachability manifests.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Fix R8 JNI seed configuration inputs

Build the seed R8 configuration from user and library consumer rules instead of final generated configuration, whose baseline native-method rule pins ACW names.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Route rewritten JNI names to original Java sources

c1fdd7e

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Allow final R8 to apply JNI mappings

445c87d

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Keep manifest entry names stable in seed R8

205ad64

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Replace early AAPT seed rule generation

fba24bd

Generate identity keep rules directly from the merged text manifest so seed R8 does not require resources to be linked early. Keep final AAPT resource rules on their normal late path and cover manifest normalization, provenance, and resource independence.\n\nCo-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Clarify activity alias manifest rules

3b99969

Assert that an activity alias identity is not treated as a Java class while its target activity remains protected.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Fix final R8 generated keep routing

52e59cf

Prepare the manifest merger directory before seed manifest rule generation, and keep generated ACW pinning rules out of final JNI-obfuscating R8 passes while retaining final AAPT and mapped reachability rules.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Prepare per-RID manifest merger inputs

134519e

Copy the shared trimmable manifest into each inner build before seed manifest merging, and validate final R8 output through its configured public mapping path.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Fix R8 JNI incremental validation tests

77b3dc4

Allow blank records when validating generated reachability manifests, and resolve the final AAPT rules through their explicit configuration provenance instead of filesystem name uniqueness.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Handle R8 mapping metadata in integration assertions

86bb28f

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>


          Normalize reverse-mapped Java source paths

6a05a22

Convert manifest-style JNI paths to the native directory separator at the filesystem copy boundary.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

simonrozsival force-pushed the simonrozsival-coreclr-r8-jni-integration branch from 15c4b79 to 6a05a22 Compare

September 3, 2026 05:00

simonrozsival marked this pull request as ready for review

September 3, 2026 10:26

simonrozsival requested a review from jonathanpeppers as a code owner

September 3, 2026 10:26

Copilot AI lite review requested due to automatic review settings

September 3, 2026 10:26

simonrozsival commented Sep 3, 2026

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/review

simonrozsival added the ready-to-review label

Copilot started reviewing on behalf of simonrozsival

September 3, 2026 10:26

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github-actions Bot commented Sep 3, 2026 •

edited

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❌ Android PR Reviewer failed. Please review the logs for details.

Generated by Android PR Reviewer for #12632

Copilot AI reviewed

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Copilot review overview

🟡 Changes recommended

The new manifest keep-rule generator currently treats a <process> element as a Java class source, which can produce incorrect keep rules and should be corrected before merge.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review tier: Lite
Findings: 1 · 1

New issues introduced by this change (2)

Severity	Finding
	`src/Xamarin.Android.Build.Tasks/Tasks/GenerateR8JniManifestProguardConfiguration.cs` — ❌ error: The manifest keep-rule generator treats a <process android:name="..."/> element as a Java…
	`src/Xamarin.Android.Build.Tasks/Tasks/R8.cs` — 💡 suggestion: GenerateCommonXamarinConfiguration writes the generated ProGuard config via…

What changed in this PR

This PR extends the .NET for Android build pipeline to support an opt-in, two-pass R8 workflow that enables JNI name obfuscation for trimmed CoreCLR builds. It introduces seed/final mapping propagation, mapping validation (XA4327), and plumbing for the new mapping/manifests through MSBuild targets and tasks.

Changes:

Add two-pass R8 seed/final mapping inputs/outputs and validation for JNI name rewriting, including a new XA4327 error code and documentation.
Introduce manifest-only keep-rule generation for the seed pass, plus additional provenance metadata on ProGuard/R8 configuration items for correct filtering.
Add/expand unit and integration tests covering mapping validation, reachability manifests, Java source path reverse-mapping, and incrementality.

File	Description
src/Xamarin.Android.Build.Tasks/Xamarin.Android.D8.targets	Wire new mapping input/output + validation inputs into the R8 invocation and FileWrites.
src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets	Add property caching, mapping output selection, compile inputs augmentation, and configuration provenance metadata.
src/Xamarin.Android.Build.Tasks/Utilities/JniRemapping/R8Mapping.cs	Add helper for obfuscated-class presence and ignore empty manifest lines in reachability checks.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Utilities/JniRemapping/R8MappingTests.cs	Add regression test ensuring reachability manifests can contain empty lines.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/TrimmableTypeMapBuildTests.cs	Add CoreCLR integration coverage for the JNI rewriting pipeline, including incrementality and multi-RID behavior.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Tasks/R8Tests.cs	Add focused tests for seed mapping behavior, baseline filtering, ACW keep-rule filtering, and XA4327 validation.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Tasks/GenerateTrimmableTypeMapTests.cs	Add tests for reverse-mapping obfuscated Java source paths and XA4327 error reporting on conflicts.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Tasks/GenerateR8JniManifestProguardConfigurationTests.cs	New tests validating deterministic manifest-only keep rules and XA4327 error cases.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Tasks/GenerateProguardConfigurationTests.cs	New tests validating mapped keep-rule output and reachability manifest generation.
src/Xamarin.Android.Build.Tasks/Tasks/R8.cs	Add seed-mapping mode, applymapping support, baseline filtering for JNI obfuscation, and mapping validation plumbing.
src/Xamarin.Android.Build.Tasks/Tasks/GenerateTrimmableTypeMap.cs	Add optional R8 mapping + rewrite manifest inputs to reverse-map generated Java source paths back to originals.
src/Xamarin.Android.Build.Tasks/Tasks/GenerateR8JniManifestProguardConfiguration.cs	New task to derive seed-pass keep rules from the merged manifest without resource resolution.
src/Xamarin.Android.Build.Tasks/Tasks/GenerateProguardConfiguration.cs	Extend to emit allowobfuscation keep rules driven by rewritten-assembly scanning plus reachability manifest output.
src/Xamarin.Android.Build.Tasks/Properties/Resources.resx	Add XA4327 and associated detail strings.
src/Xamarin.Android.Build.Tasks/Properties/Resources.Designer.cs	Update generated resource accessors for XA4327 strings.
src/Xamarin.Android.Build.Tasks/MSBuild/Xamarin/Android/Xamarin.Android.Aapt2.targets	Mark AAPT-generated rules with metadata to preserve/identify provenance for filtering.
src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.targets	Add seed-pass compilation/mapping targets and shared-output wiring for inner builds.
src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.CoreCLR.targets	Ensure proguard config generation participates in dalvik compile deps; add pre-ILLink rewrite stage and extend inputs/outputs.
Documentation/docs-mobile/TOC.yml	Add XA4327 doc entry to TOC.
Documentation/docs-mobile/messages/xa4327.md	New documentation page for XA4327.
Documentation/docs-mobile/messages/index.md	Add XA4327 to the error index list.
Documentation/docs-mobile/building-apps/build-properties.md	Document the new AndroidEnableR8JniNameObfuscation property and requirements.

Files not reviewed (1)

src/Xamarin.Android.Build.Tasks/Properties/Resources.Designer.cs: Generated file

src/Xamarin.Android.Build.Tasks/Tasks/GenerateR8JniManifestProguardConfiguration.cs

Comment on lines +56 to +60

+              				case "provider":
+              				case "instrumentation":
+              				case "process":
+              					AddClass (classes, packageName, element, "name");
+              					break;

src/Xamarin.Android.Build.Tasks/Tasks/R8.cs

+              				return;
+              			}
+              			using var xamcfg = File.CreateText (ProguardCommonXamarinConfiguration);

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