[TrimmableTypeMap] Extract typemap targets into dedicated files by simonrozsival · Pull Request #10797 · dotnet/android

simonrozsival · 2026-02-10T20:12:57Z

Summary

Extracts all typemap-related MSBuild targets from Xamarin.Android.Common.targets and Microsoft.Android.Sdk.ILLink.targets into dedicated files, conditionally imported based on _AndroidTypeMapImplementation. This is a pure refactoring to enable future addition of a "trimmable" typemap implementation (see #10779).

Changes

New files

Microsoft.Android.Sdk.TypeMap.LlvmIr.targets — All current typemap targets extracted from Common.targets and ILLink.targets: JCW generation, manifest generation, typemap generation, ILLink customization (_PrepareLinking, _FixRootAssembly, _TouchAndroidLinkFlag), mono.android.jar handling, TypeManager.java creation, _RemoveRegisterAttribute, FastDev type map collection
Microsoft.Android.Sdk.TypeMap.Trimmable.targets — Dispatcher stub that imports CoreCLR/NativeAOT sub-targets + runtime validation + empty _GenerateJavaStubs placeholder
Microsoft.Android.Sdk.TypeMap.Trimmable.CoreCLR.targets — Empty stub
Microsoft.Android.Sdk.TypeMap.Trimmable.NativeAOT.targets — Empty stub

Modified files

Xamarin.Android.Common.targets — Removed typemap task invocations (moved to LlvmIr.targets), added conditional imports, added _ValidateAndroidTypeMapImplementation and _LinkAssemblies targets
Microsoft.Android.Sdk.After.targets — Removed ILLink.targets import (no longer needed)

Deleted files

Microsoft.Android.Sdk.ILLink.targets — All content moved to LlvmIr.targets and Common.targets

Design decisions

Files follow the Microsoft.Android.Sdk.* naming convention and live in the targets/ directory
_LinkAssemblies (generic orchestration) moved to Common.targets since it applies to all typemap implementations
ILLink customization targets (_PrepareLinking, etc.) moved to LlvmIr.targets since they are specific to the current typemap implementation
_ValidateAndroidTypeMapImplementation validates the property value at build time (valid: llvm-ir, managed, trimmable)
Trimmable stubs are truly empty — no new C# code or tasks

Closes to #10779

Extract all typemap-related MSBuild targets from Xamarin.Android.Common.targets and Microsoft.Android.Sdk.ILLink.targets into a dedicated Xamarin.Android.TypeMap.Legacy.targets file, imported conditionally based on _AndroidTypeMapImplementation. Create empty stub files for the trimmable typemap implementation (Trimmable.targets, Trimmable.CoreCLR.targets, Trimmable.NativeAOT.targets). This is a pure refactoring — no new tasks, no new C# code, no behavioral changes. When _AndroidTypeMapImplementation != 'trimmable' (the default), the legacy targets are imported and the build pipeline is identical to before. Changes: - New: Xamarin.Android.TypeMap.Legacy.targets — all legacy typemap targets - _GenerateLegacyJavaCallableWrappers (JCW gen, ACW map, stubs, marshal methods) - _GenerateLegacyAndroidManifest (manifest + additional providers) - _GenerateLegacyTypeMappings (LLVM IR typemaps) - _SetLegacyTypemapProperties (_TypeMapKind) - _GetMonoPlatformJarPath (overrides empty stub) - _PrepareNativeAssemblySources (overrides empty stub) - _AddLegacyTypeManagerResources (TypeManager.java + mono.android.jar) - _RemoveRegisterAttribute (full version with RemoveRegisterAttribute task) - _CollectLegacyTypeMapFiles (FastDev archive) - New: Xamarin.Android.TypeMap.Trimmable.targets — dispatcher + validation stub - New: Xamarin.Android.TypeMap.Trimmable.CoreCLR.targets — empty stub - New: Xamarin.Android.TypeMap.Trimmable.NativeAOT.targets — empty stub - Modified: Common.targets — stripped of all legacy typemap task invocations, added empty stubs + conditional imports - Modified: ILLink.targets — added conditions to skip legacy ILLink steps when _AndroidTypeMapImplementation == 'trimmable' Fixes: #10779

…erateLegacyAndroidManifest GenerateMainAndroidManifest unregisters NativeCodeGenState from the build engine, so GenerateTypeMappings must retrieve it first. Add DependsOnTargets to ensure correct ordering between the two AfterTargets targets.

Move _PrepareLinking, _FixRootAssembly, and _TouchAndroidLinkFlag from Microsoft.Android.Sdk.ILLink.targets into Xamarin.Android.TypeMap.Legacy.targets. This eliminates scattered _AndroidTypeMapImplementation != 'trimmable' conditions in ILLink.targets — the conditions are now implicit since Legacy.targets is only imported when _AndroidTypeMapImplementation is not 'trimmable'.

jonathanpeppers · 2026-02-10T22:55:37Z

src/Xamarin.Android.Build.Tasks/Xamarin.Android.Build.Tasks.targets

+    <None Include="Xamarin.Android.TypeMap.LlvmIr.targets">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>


New files we've been naming Microsoft.Android.Sdk.*.targets and putting in the targets folder. The Xamarin.* ones are old.

You might also check, if we can have a wildcard, where you don't need to add any new @(None) items.

Done — renamed to Microsoft.Android.Sdk.TypeMap.*.targets and moved to targets/ in the next commit. Also switched to a wildcard @(None) pattern.

Address PR feedback: - Rename Xamarin.Android.TypeMap.*.targets -> Microsoft.Android.Sdk.TypeMap.*.targets - Move files to Microsoft.Android.Sdk/targets/ (new file convention) - Remove @(None) entries (handled by _CopyNetSdkTargets wildcard) - Delete Microsoft.Android.Sdk.ILLink.targets (moved _LinkAssemblies to Common.targets) - Add _ValidateAndroidTypeMapImplementation target - Add _GenerateJavaStubs stub in Trimmable.targets - Fix UsingTask references to use $(_XamarinAndroidBuildTasksAssembly) - Fix ILLink DLL paths for targets/ directory context

Copilot

Pull request overview

This PR extracts all typemap-related MSBuild targets from Xamarin.Android.Common.targets and Microsoft.Android.Sdk.ILLink.targets into dedicated, conditionally-imported files to enable future addition of a "trimmable" typemap implementation. This is a pure refactoring with no new functionality.

Changes:

Extracted legacy typemap targets (llvm-ir and managed implementations) into Microsoft.Android.Sdk.TypeMap.LlvmIr.targets
Created stub files for future trimmable typemap implementation: Trimmable.targets, Trimmable.CoreCLR.targets, and Trimmable.NativeAOT.targets
Moved shared _LinkAssemblies target to Common.targets and deleted Microsoft.Android.Sdk.ILLink.targets

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
`Xamarin.Android.Common.targets`	Removed typemap UsingTask declarations, removed inline targets (_GenerateJavaStubs, _GetMonoPlatformJarPath, etc.), added conditional imports for LlvmIr/Trimmable targets, moved _LinkAssemblies here, gutted _RemoveRegisterAttribute to base implementation
`Microsoft.Android.Sdk.TypeMap.LlvmIr.targets`	New file containing all legacy typemap logic: UsingTask declarations, _GenerateJavaStubs, _PrepareLinking, _GetMonoPlatformJarPath, _PrepareNativeAssemblySources, _AddTypeManagerResources, _RemoveRegisterAttribute override, _CollectTypeMapFiles, ILLink customization
`Microsoft.Android.Sdk.TypeMap.Trimmable.targets`	New stub file with runtime-specific imports, runtime validation, and empty _GenerateJavaStubs placeholder
`Microsoft.Android.Sdk.TypeMap.Trimmable.CoreCLR.targets`	Empty stub for future CoreCLR-specific trimmable implementation
`Microsoft.Android.Sdk.TypeMap.Trimmable.NativeAOT.targets`	Empty stub for future NativeAOT-specific trimmable implementation
`Microsoft.Android.Sdk.ILLink.targets`	Deleted - all content moved to LlvmIr.targets and Common.targets
`Microsoft.Android.Sdk.After.targets`	Removed import of deleted ILLink.targets file

...droid.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.LlvmIr.targets

...id.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.targets

jonathanpeppers · 2026-02-11T16:22:08Z

/azp run

azure-pipelines · 2026-02-11T16:22:25Z

Azure Pipelines successfully started running 1 pipeline(s).

jonathanpeppers

There are some test failures related to NativeAOT, I bet this is now skipping a few targets there that are needed:

…e stub - Restore missing TypeMappingStep ILLink custom step for managed typemap implementation (used by NativeAOT) - Add proper DependsOnTargets, Inputs/Outputs, and stamp file to the trimmable _GenerateJavaStubs stub for incremental build support - Add TODO comment about manifest extraction (#10807): both GenerateMainAndroidManifest and GenerateAdditionalProviderSources depend on NativeCodeGenState and need to be decoupled before they can be shared across typemap paths

simonrozsival · 2026-02-12T15:14:54Z

/azp run

azure-pipelines · 2026-02-12T15:15:13Z

Azure Pipelines successfully started running 1 pipeline(s).

simonrozsival · 2026-02-12T15:17:20Z

Re: NativeAOT test failures — the TypeMappingStep ILLink custom step for _AndroidTypeMapImplementation == 'managed' was dropped during the migration from ILLink.targets. Restored in d19b541. Local tests (including BuildBasicApplicationNativeAOT variants) pass now.

The TypeMap imports must be last in Common.targets so that their target overrides (e.g. _RemoveRegisterAttribute with Inputs/Outputs) take precedence over the base definitions. Previously, the imports were at line 388 while the base _RemoveRegisterAttribute was at line 1915, causing the base version (without Inputs/Outputs/Touch) to override the LlvmIr version, breaking incremental builds.

simonrozsival · 2026-02-12T18:25:44Z

/azp run

azure-pipelines · 2026-02-12T18:25:57Z

Azure Pipelines successfully started running 1 pipeline(s).

jonathanpeppers

Xamarin.Android-PR is green, but weird dotnet-public is running again.

I'll merge shortly, we don't have to wait.

sbomer · 2026-02-12T21:16:10Z

...droid.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.LlvmIr.targets

+  </Target>
+
+  <!-- ILLink customization: custom trimmer steps, root descriptors, etc. -->
+  <Target Name="_PrepareLinking"


Why was this moved to TypeMap.LlvmIr.targets? It looks like general ILLink logic, not specifically related to type map. @simonrozsival

I wanted to make room for changes to ILLink configuration for the new typemap. It's quite likely that some of the configuration will be brought back in the next steps. If there's too much duplication in the ILLink config between the two typemap variants, we can add the ILLink.targest file back.

Thanks - I think it would make sense to factor this so that the common logic not related to type maps is shared if possible. Otherwise this introduces another place where the configs can drift, which would increase the work it takes to migrate away from custom steps.

The Trimmable Type Map won't have any custom steps. At the same time, I'm not sure if we will be able to really remove the custom steps from the legacy typemap. We will likely be able to generate (huge) ILLink descriptors XML files that would replace the custom marking logic, but I'm not sure if that's worth the effort. We discussed using ILLink from .NET 10 with Mono in .NET 11. Do you think that could be a viable option? Mono will still need to use .dlls without runtime async, so I would expect one version old ILLink would be able to trim these assemblies just fine? For CoreCLR, we would use .NET 11 ILLink and for NativeAOT there won't be any ILLink step in the build pipeline.

We discussed using ILLink from .NET 10 with Mono in .NET 11. Do you think that could be a viable option?

It may be viable, but it seems like a fragile setup. Any new language features that show up in .NET 11 won't necessarily be supported with the .NET 10 ILLink, unless we continue adding features in servicing, and at that point we might as well consider shipping a separate .NET 11 illink for mono.

simonrozsival added 2 commits February 10, 2026 16:09

simonrozsival force-pushed the android-trimmabletypemap-01-build-targets-refactoring branch 6 times, most recently from d996077 to c9ab4a4 Compare February 10, 2026 22:19

simonrozsival force-pushed the android-trimmabletypemap-01-build-targets-refactoring branch from c9ab4a4 to 3a234cb Compare February 10, 2026 22:22

jonathanpeppers reviewed Feb 10, 2026

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simonrozsival changed the title ~~[Build] Extract legacy typemap targets into dedicated files~~ [Build] Extract typemap targets into dedicated files Feb 11, 2026

simonrozsival added the copilot `copilot-cli` or other AIs were used to author this label Feb 11, 2026

simonrozsival marked this pull request as ready for review February 11, 2026 11:33

simonrozsival requested a review from grendello as a code owner February 11, 2026 11:33

Copilot AI review requested due to automatic review settings February 11, 2026 11:33

Copilot started reviewing on behalf of simonrozsival February 11, 2026 11:33 View session

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jonathanpeppers reviewed Feb 11, 2026

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simonrozsival changed the title ~~[Build] Extract typemap targets into dedicated files~~ [TrimmableTypeMap] Extract typemap targets into dedicated files Feb 12, 2026

simonrozsival mentioned this pull request Feb 12, 2026

[TrimmableTypeMap] Add JavaPeerScanner using System.Reflection.Metadata #10805

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simonrozsival added Area: NativeAOT Issues that only occur when using NativeAOT. Area: CoreCLR Issues that only occur when using CoreCLR. labels Feb 12, 2026

simonrozsival added the trimmable-type-map label Feb 12, 2026

simonrozsival added this to the .NET 11 milestone Feb 12, 2026

jonathanpeppers approved these changes Feb 12, 2026

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jonathanpeppers merged commit 9b2fc03 into main Feb 12, 2026
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jonathanpeppers deleted the android-trimmabletypemap-01-build-targets-refactoring branch February 12, 2026 20:37

sbomer reviewed Feb 12, 2026

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