[typemap] Preserve supported Unicode JCW names

[simonrozsival]

Summary

• preserve supported BMP Unicode Java identifiers across trimmable JCW source paths, declarations, manifest names, ACW mappings, typemap keys, DEX, and JNI activation
• reject combining/format characters, supplementary code points, malformed segments, and reserved identifiers early with XA4258 before trimmable outputs are written
• add semantic javac/classfile, three-runtime host, and three-runtime device activation coverage

Fixes part of #12561.

Validation

• 887 trimmable typemap unit tests
• generated Java semantic parity + javac tests
• 12-case llvm-ir/CoreCLR/NativeAOT host matrix
• llvm-ir CoreCLR, trimmable CoreCLR, and trimmable NativeAOT device activation matrix
• legacy JCW identifier and package-name diagnostic tests

[Copilot]

Copilot review overview

🟢 Approval recommended

Review tier: Lite
Findings: 1

New issues introduced by this change (1)

Severity	Finding
	src/​Microsoft.Android.Sdk.TrimmableTypeMap/​JavaNameValidator.cs — 💡 suggestion — When a package/JNI name contains an empty segment (e.g. consecutive separators),…

What changed in this PR

This PR extends the trimmable typemap/JCW pipeline to preserve supported BMP Unicode Java identifiers end-to-end (typemap keys, JCW source paths/declarations, ACW mappings, manifest component names, DEX, and runtime/JNI activation), while rejecting unsupported Unicode forms early via XA4258.

Changes:

• Tighten Java/JNI name validation to accept a constrained set of stable BMP identifiers and reject combining/format/supplementary code points with XA4258.
• Add generator + integration + device/runtime coverage to prove Unicode identifiers survive generation/compilation/activation across llvm-ir/CoreCLR/NativeAOT matrices.
• Update XA4258 wording and documentation to reflect the broader “invalid or unsupported” identifier class.

File	Description
tests/​MSBuildDeviceIntegration/​Tests/​InstallAndRunTests.cs	Adds device activation test for an Activity with a Unicode Java identifier.
tests/​Mono.Android-Tests/​Mono.Android-Tests/​Java.Interop/​ConstructorActivationTests.cs	Adds Java-side constructor/peer-registration test for a Unicode-registered type.
tests/​Microsoft.Android.Sdk.TrimmableTypeMap.Tests/​Generator/​TypeMapModelBuilderTests.cs	Verifies typemap model preserves Unicode code points in map keys/JNI names.
tests/​Microsoft.Android.Sdk.TrimmableTypeMap.Tests/​Generator/​TrimmableTypeMapGeneratorTests.cs	Expands XA4258 validation coverage for unsupported Unicode/identifier shapes and updates expected message text.
tests/​Microsoft.Android.Sdk.TrimmableTypeMap.Tests/​Generator/​ManifestGeneratorTests.cs	Ensures manifest component names preserve Unicode code points.
tests/​Microsoft.Android.Sdk.TrimmableTypeMap.Tests/​Generator/​JcwJavaSourceGeneratorTests.cs	Extends JNI name validation tests for decomposed/supplementary forms and validates a Unicode-good case.
tests/​Microsoft.Android.Sdk.TrimmableTypeMap.Tests/​Generator/​JavaNameValidatorTests.cs	Adds focused unit tests for valid BMP Unicode identifiers and rejected unsupported cases.
tests/​Microsoft.Android.Sdk.TrimmableTypeMap.Tests/​Generator/​AcwMapWriterTests.cs	Verifies ACW map writing preserves Unicode identifiers.
tests/​Microsoft.Android.Sdk.TrimmableTypeMap.IntegrationTests/​JavaSourceSemanticParityTests.cs	Adds semantic parity compilation path assertions for Unicode-generated Java artifacts.
tests/​Microsoft.Android.Sdk.TrimmableTypeMap.IntegrationTests/​JavaSourceParityFixture/​JavaSourceParityTypes.cs	Adds a fixture Activity registered under a Unicode Java name.
src/​Xamarin.Android.Build.Tasks/​Tests/​Xamarin.Android.Build.Tests/​TrimmableTypeMapBuildTests.cs	Adds build-time assertions that Unicode names survive intermediate outputs/manifest/acw-map and documents DEX limitations for supplementary code points.
src/​Xamarin.Android.Build.Tasks/​Properties/​Resources.resx	Updates XA4258 resource text to “invalid or unsupported”.
src/​Xamarin.Android.Build.Tasks/​Properties/​Resources.Designer.cs	Regenerates designer text for the updated XA4258 resource.
src/​Microsoft.Android.Sdk.TrimmableTypeMap/​JavaNameValidator.cs	Implements restricted Unicode identifier support/validation logic for stable toolchain behavior.
src/​Microsoft.Android.Sdk.TrimmableTypeMap/​Generator/​JniSignatureHelper.cs	Routes JNI-name validation through the centralized JavaNameValidator checks and updates exception text.
src/​Microsoft.Android.Sdk.TrimmableTypeMap/​Generator/​JcwJavaSourceGenerator.cs	Updates documentation for what JNI-name validation now enforces.
Documentation/​docs-mobile/​messages/​xa4258.md	Updates XA4258 docs to explain unsupported Unicode categories and toolchain constraints.
Documentation/​docs-mobile/​messages/​index.md	Updates XA4258 index entry to match new wording.

Files not reviewed (1)

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

Suppressed comments (1)

src/Microsoft.Android.Sdk.TrimmableTypeMap/JavaNameValidator.cs:98

• 💡 suggestion — Similar to package validation, TryGetInvalidJniNameSegment can report an empty invalidSegment for malformed JNI names (leading/trailing/consecutive /). That produces error text like identifier ''. Substituting a placeholder makes XA4258/ArgumentException messages clearer.

		var segments = jniName.Split ('/');
		for (int i = 0; i < segments.Length - 1; i++) {
			if (IsInvalidIdentifier (segments [i], isTypeName: false)) {
				invalidSegment = segments [i];
				return true;
			}