[Microsoft.Android.Build.Tasks] Generate typemap ProGuard rules - #12821

Complete layer 6 of the frozen #12821 split: activate the shared retained-typemap pipeline, wire R8 retention policies, remove DGML generation, and restore the deferred activation coverage and documentation. Preserve the base XA1037 localization changes.

Co-authored-by: Copilot App <[email protected]>

Complete layer 6 of the frozen #12821 split: activate the shared retained-typemap pipeline, wire R8 retention policies, remove DGML generation, and restore the deferred activation coverage and documentation. Preserve the base XA1037 localization changes.

Co-authored-by: Copilot App <[email protected]>

Layer 1 of 6 splitting #12821; build activation comes in later layers.

Establish a shared retained-Java-key contract so the runtime-specific extractors can feed the same ProGuard generators without duplicating rule generation. This is a focused slice of the validated source at `87bd3f8a8b512859339e5446c1f86709a6c28c3b`, based on `main` at `d63fe4c9f8cf8def6049c9415bb0abf4269ee0f5`.

### Scope and contract

- Add canonical JNI class-name and alias-key utilities. The shared interchange format is sorted, unique JNI class names, UTF-8 without BOM, with LF line endings.
- Add `<GenerateTypeMapProguardConfiguration/>`, which unions canonical keys and emits only `-keep class` rules. Reject invalid names/rule injection and missing inputs before overwriting output; valid empty inputs produce empty output.
- Add `<GenerateTypeMapMemberProguardConfiguration/>`, which keeps **all members of retained classes**. This is not precise-method inference.
- Add shared XA4327/XA4328 diagnostics and documentation while preserving XA4319/XA4320/XA4321 and the newer base localization changes.
- Add the standalone production-task reference, minimal build engine, six generator unit-test methods, and the final-source NUnit fixture.

No extractors, target imports, `UsingTask` activation, R8 policy changes, runtime changes, or DGML removal are included. The standalone `TypeMapProguardTests` fixture is intentionally a generator-only subset; later layers add its adapter/target/configuration coverage.

### Validation

`dotnet test tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests.csproj -v minimal --filter 'FullyQualifiedName~TypeMapProguardTests'`

**15 passed, 0 failed, 0 skipped**, compiling the actual modern production task project and its source-linked shared resources.

The focused NUnit command was also attempted. Its existing legacy `Xamarin.Android.Build.Tasks` project reference requires the missing `bin/BuildDebug/net10.0/xa-prep-tasks.dll` (`GitBlame`/`GitCommitHash`, MSB4062) in this clean worktree. The unchanged frozen-source fixture is retained; no full SDK/bootstrap build or test-project infrastructure changes were made.

`git diff --check` passes. Complete extracted files match the frozen source byte-for-byte; retained standalone test/helper methods match the frozen source. The diff is additive only: 14 files, 546 insertions.

Extract surviving generic TypeMapAttribute keys from linked managed assemblies, with canonical alias and array normalization and explicit malformed-input failures. Add focused production-task coverage including the pinned real ILLink fixture.

Layer 3 of the #12821 split; MSBuild activation remains in a later layer.

Co-authored-by: Copilot App <[email protected]>

Extract canonical Java class keys from CoreCLR LLVM string blobs without relying on optional comments. Preserve strict diagnostics and array normalization with standalone and real-emitter test fixtures.

Layer 2 of 6 splitting #12821; runtime activation follows in a later layer.

Co-authored-by: Copilot App <[email protected]>

Extract surviving generic TypeMapAttribute keys from linked managed assemblies, with canonical alias and array normalization and explicit malformed-input failures. Add focused production-task coverage including the pinned real ILLink fixture.

Layer 3 of the #12821 split; MSBuild activation remains in a later layer.

Co-authored-by: Copilot App <[email protected]>

Extract surviving generic TypeMapAttribute keys from linked managed assemblies, with canonical alias and array normalization and explicit malformed-input failures. Add focused production-task coverage including the pinned real ILLink fixture.

Layer 3 of the #12821 split; MSBuild activation remains in a later layer.

Co-authored-by: Copilot App <[email protected]>

Complete layer 6 of the frozen #12821 split: activate the shared retained-typemap pipeline, wire R8 retention policies, remove DGML generation, and restore the deferred activation coverage and documentation. Preserve the base XA1037 localization changes.

Co-authored-by: Copilot App <[email protected]>

Extract surviving generic TypeMapAttribute keys from linked managed assemblies, with canonical alias and array normalization and explicit malformed-input failures. Add focused production-task coverage including the pinned real ILLink fixture.

Layer 3 of the #12821 split; MSBuild activation remains in a later layer.

Co-authored-by: Copilot App <[email protected]>

## Why

Layer 1 of 4 in the remaining #12821 stack, based on main. The foundation #12822 has merged; the LLVM adapter #12823 is closed and omitted. Typemap-derived ProGuard rules need the Java class keys that survive ILLink, rather than pre-link registration metadata or stale alias arrays.

## Changes

Add `ExtractTypeMapKeysFromAssemblies` in the modern `Microsoft.Android.Build.Tasks` assembly. It reads surviving assembly-level generic `TypeMapAttribute` entries, unions and sorts their keys, normalizes alias suffixes and object-array descriptors, and writes canonical UTF-8 output. Empty linked stubs are valid; absent inputs, malformed assemblies/attributes/keys, and output failures report XA4327.

Source-link the existing metadata helpers and enable unsafe blocks in the modern task project. Add the pinned ILLink package and its path metadata to the standalone test project, retaining its production-task `ProjectReference`.

This layer does not activate the task in MSBuild or change R8 policy. Native-object extraction, orchestration, and legacy cleanup remain in later layers. The copied extractor and fixture exactly match frozen source `87bd3f8a8b512859339e5446c1f86709a6c28c3b`; the test-project native-object metadata is intentionally deferred to layer 4.

## Validation

On .NET SDK `11.0.100-preview.7.26381.103`, the following focused standalone run passed **89/89**, with no skips, using the actual modern production task DLL. This includes `RealILLinkRetainsOnlyLiveTypeMapAttributes` with pinned `Microsoft.NET.ILLink.Tasks` `11.0.0-rc.2.26461.115`.

```sh
dotnet test tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests.csproj -v minimal --filter 'FullyQualifiedName~ExtractTypeMapKeysFromAssembliesTests|FullyQualifiedName~ExtractTypeMapKeysFromLlvmIrArrayTests|FullyQualifiedName~TypeMapProguardTests'
```

Base: `main`. Bottom of native stack #12893.

## Why

Layer 2 of 4 in native stack #12893, depending on #12824. This adds the NativeAOT representation adapter so typemap-based ProGuard rules can consume the keys retained in the final ILC native object rather than infer retention from a dependency graph.

## Extraction contract

- `ExtractTypeMapKeysFromNativeAotObject` reads final relocatable ELF objects using LLVM section/symbol metadata and common-fixup relocations to select the Java type-map groups by their EEType identities. It does not scan arbitrary strings or guess group membership from key appearance.
- `NativeAotTypeMapReader` enumerates the selected NativeFormat groups, reusing the existing alias/array normalization and class-name validation helpers. Output is a deterministic union of canonical class keys; invalid required inputs fail with XA4327.
- Add the frozen parser/adapter coverage, native-object fixture helpers, tool-path test metadata, and test-catalog instructions. All eight changed files match the frozen #12821 snapshot exactly.

## Tools and scope

Extraction requires an existing full path to NDK `llvm-readobj` with adjacent `llvm-objdump`; native test fixtures additionally need adjacent `clang`. Supply `-p:_NativeAotLlvmReadObjPath=/path/to/ndk/bin/llvm-readobj` for native-tool test cases.

This layer does **not** activate product targets, add assembly-resolution metadata, expand shared target integration tests, change R8 policy, enable NativeAOT trimming, or retire DGML. The existing DGML pipeline remains active; build activation and policy follow in layers 3 and 4.

## Validation

Standalone trimmable typemap project built with .NET 11 preview 7 and `-p:_AndroidTreatWarningsAsErrors=true`, passing the existing NDK tool path. Targeted NativeAOT, linked-DLL, LLVM, ProGuard-generator, typemap-generator, and class-name coverage: **694 passed, 0 failed, 0 skipped**.

`NativeAotObjectIntegrationTests.cs` contains shared tool/attribute helpers at this layer; real-object MSBuild integration test methods depend on the later shared target-test expansion and are not claimed as executed here.

Complete layer 6 of the frozen #12821 split: activate the shared retained-typemap pipeline, wire R8 retention policies, remove DGML generation, and restore the deferred activation coverage and documentation. Preserve the base XA1037 localization changes.

Co-authored-by: Copilot App <[email protected]>

Complete layer 6 of the frozen #12821 split: activate the shared retained-typemap pipeline, wire R8 retention policies, remove DGML generation, and restore the deferred activation coverage and documentation. Preserve the base XA1037 localization changes.

Co-authored-by: Copilot App <[email protected]>