IL Trim attributes with a feature flag in all assemblies

[pavelsavara]

• Trim attributes with a feature flag in all assemblies, not just corelib
• test it on MetadataUpdateHandlerAttribute

DebuggableAttribute
DebuggerBrowsableAttribute
DebuggerDisplayAttribute
DebuggerHiddenAttribute
DebuggerNonUserCodeAttribute
DebuggerStepperBoundaryAttribute
DebuggerStepThroughAttribute
DebuggerTypeProxyAttribute
DebuggerVisualizerAttribute
Tracing.EventAttribute
Tracing.EventDataAttribute
Tracing.EventFieldAttribute
Tracing.EventIgnoreAttribute
Tracing.EventSourceAttribute
Tracing.NonEventAttribute
MetadataUpdateHandlerAttribute
ClassInterfaceAttribute
ComDefaultInterfaceAttribute
ComEventInterfaceAttribute
ComSourceInterfacesAttribute
ComVisibleAttribute
DispIdAttribute
InterfaceTypeAttribute
ProgIdAttribute
TypeMapAssemblyTargetAttribute
TypeMapAssociationAttribute
TypeMapAttribute

[Copilot]

Pull request overview

This PR adds ILLink link-attributes to remove MetadataUpdateHandlerAttribute instances (and enable trimming of their referenced handler types) when System.Reflection.Metadata.MetadataUpdater.IsSupported is disabled, and adds a trimming test to validate the behavior.

Changes:

• Add per-library ILLink.LinkAttributes.xml files to remove MetadataUpdateHandlerAttribute instances when the feature switch is false.
• Wire the new link-attributes files into the affected library projects via ILLinkLinkAttributesXmls.
• Add a new System.Runtime trimming test console app that disables the feature switch and verifies the attribute + handler types are absent.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/libraries/System.Text.Json/src/System.Text.Json.csproj	Embeds ILLink link-attributes for conditional removal of MetadataUpdateHandlerAttribute instances.
src/libraries/System.Text.Json/src/ILLink/ILLink.LinkAttributes.xml	Removes MetadataUpdateHandlerAttribute instances when MetadataUpdater.IsSupported is disabled.
src/libraries/System.Runtime/tests/System.Runtime.Tests/TrimmingTests/System.Runtime.TrimmingTests.proj	Adds a new trimming test app and disables the MetadataUpdater.IsSupported feature switch for it.
src/libraries/System.Runtime/tests/System.Runtime.Tests/TrimmingTests/MetadataUpdateHandlerTrimmed.cs	New trimming test app validating attribute + handler types are trimmed under the disabled switch.
src/libraries/System.ComponentModel.TypeConverter/src/System.ComponentModel.TypeConverter.csproj	Embeds ILLink link-attributes for conditional removal of MetadataUpdateHandlerAttribute instances.
src/libraries/System.ComponentModel.TypeConverter/src/ILLink/ILLink.LinkAttributes.xml	Removes MetadataUpdateHandlerAttribute instances when MetadataUpdater.IsSupported is disabled.
src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/Microsoft.Extensions.DependencyInjection.Abstractions.csproj	Embeds ILLink link-attributes for conditional removal of MetadataUpdateHandlerAttribute instances.
src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ILLink/ILLink.LinkAttributes.xml	Removes MetadataUpdateHandlerAttribute instances when MetadataUpdater.IsSupported is disabled.

[Copilot]

Pull request overview

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

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

[pavelsavara]

cc @tmat for MetadataUpdateHandlerAttribute, related dotnet/aspnetcore#65903

[jkotas]

Trim attributes with a feature flag in all assemblies, not just corelib

What are the assemblies that define these attributes outside CoreLib?

[dotnet-policy-service]

Tagging subscribers to this area: @agocke, @dotnet/illink
See info in area-owners.md if you want to be subscribed.

[jkotas]

I would expect <assembly fullname="System.Private.CoreLib" to be defining identify of the attribute, so * does not make sense.

[pavelsavara]

Trim attributes with a feature flag in all assemblies, not just corelib

What are the assemblies that define these attributes outside CoreLib?

runtime/src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ActivatorUtilities.cs

Line 16 in f190fcc

[assembly: System.Reflection.Metadata.MetadataUpdateHandler(typeof(Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ActivatorUtilitiesUpdateHandler))]

runtime/src/libraries/System.ComponentModel.TypeConverter/src/System/ComponentModel/ReflectionCachesUpdateHandler.cs

Line 8 in f190fcc

[assembly: MetadataUpdateHandler(typeof(ReflectionCachesUpdateHandler))]

There are many in aspnetcore

https://github.com/search?q=repo%3Adotnet%2Faspnetcore+MetadataUpdateHandler&type=code

[jkotas]

What are the assemblies that define these attributes outside CoreLib?

These are uses of the attributes. You should not need the wildcard for those. The wildcard should be only needed for compiler injected local copies of the attributes.