Add trim/aot analyzer warnings for transitive references

[sbomer]

Adds new analyzer warnings for references to assemblies not marked as trim or aot compatible.

The new warnings are opt-in under the following settings:

• <VerifyReferenceTrimCompatibility>true</VerifyReferenceTrimCompatibility>
• <VerifyReferenceAotCompatibility>true</VerifyReferenceAotCompatibility>

The analyzer uses AssemblyMetadataAttribute in the referenced assemblies to detect whether they are marked as trim/aot compatible. To mark a project as trim/aot compatible, it should be built with the usual recommended property settings:

• <IsTrimmable>true</IsTrimmable> adds [assembly: AssemblyMetadata("IsTrimmable", "True")]
• <IsAotCompatible>true</IsAotCompatible> adds [assembly: AssemblyMetadata("IsAotCompatible", "True")

Fixes #117712

[Copilot]

Pull Request Overview

This PR introduces new analyzer warnings to detect when assemblies referenced by a project are not marked as trim or AOT compatible. The warnings are opt-in via the VerifyReferenceTrimCompatibility and VerifyReferenceAotCompatibility MSBuild properties, helping developers identify potentially problematic dependencies during trimming or AOT compilation scenarios.

Key changes:

• Adds two new diagnostic IDs for trim and AOT compatibility warnings
• Extends the existing trim and AOT analyzers to check referenced assemblies for compatibility metadata
• Provides comprehensive test coverage for the new functionality

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
ReferenceTrimCompatibilityTests.cs	Test cases for the new trim compatibility analyzer warnings
ReferenceCompatibilityTestUtils.cs	Utility class to create test scenarios with external assembly references
ReferenceAotCompatibilityTests.cs	Test cases for the new AOT compatibility analyzer warnings
ILLink.RoslynAnalyzer.Tests.csproj	Simplifies reference assembly copying for tests
SharedStrings.resx	Adds resource strings for the new diagnostic messages
DiagnosticId.cs	Defines new diagnostic IDs for trim and AOT compatibility warnings
Microsoft.NET.ILLink.Analyzers.props	Exposes the new MSBuild properties to the compiler
RequiresUnreferencedCodeAnalyzer.cs	Implements trim compatibility checking for referenced assemblies
RequiresDynamicCodeAnalyzer.cs	Implements AOT compatibility checking for referenced assemblies
RequiresAnalyzerBase.cs	Adds infrastructure to support compilation-level analysis actions
MSBuildPropertyOptionNames.cs	Defines constants for the new MSBuild property names

Comments suppressed due to low confidence (2)

src/tools/illink/src/ILLink.RoslynAnalyzer/RequiresUnreferencedCodeAnalyzer.cs:67

• The variable name 'isTrimmable' is misleading as it stores the attribute object, not a boolean value. Consider renaming it to 'trimCompatibilityAttribute' or 'isTrimmableAttribute'.

                var isTrimmable = refAssembly.GetAttributes().FirstOrDefault(attr =>

src/tools/illink/src/ILLink.RoslynAnalyzer/RequiresDynamicCodeAnalyzer.cs:46

• The variable name 'isAotCompatible' is misleading as it stores the attribute object, not a boolean value. Consider renaming it to 'aotCompatibilityAttribute' or 'isAotCompatibleAttribute'.

                var isAotCompatible = refAssembly.GetAttributes().FirstOrDefault(attr =>

[sbomer]

@ViktorHofer @dotnet/illink I've changed the analyzer tests to run against a live ref pack (the one we just built) to get the latest IsTrimmable/IsAotCompatible metadata. This means the dotnet-linker-tests pipeline will need to build libs before running analyzer tests. Any concerns with this?

[ViktorHofer]

Any concerns with this?

No concerns with that. You can build just the libs.sfx subset if you want to optimize.