Missing `[RequiresUnreferencedCodeAttribute]` annotation for trimming

[zeroskyx]

Greetings,

due to the call of this.WriteEvent, the library throws trim warnings since RequiresUnreferencedCodeAttribute is not currently propagated to the invoking methods.

Minimal reproduction

1. Create new console app: dotnet new console
2. Add RecycleableMemoryStream package: dotnet add package Microsoft.IO.RecyclableMemoryStream
3. Replace contents of Program.cs with: _ = new Microsoft.IO.RecyclableMemoryStreamManager();
4. Publish trimmed assembly, and show all trim warnings: dotnet publish -p:PublishTrimmed=true -p:EnableTrimAnalyzer=true -p:TrimmerSingleWarn=false

Expected result

The compilation and trimming concludes without any warnings

Actual result

The compilation emits trim warnings such as: /_/src/Events.cs(83,21): Trim analysis warning IL2026: Microsoft.IO.RecyclableMemoryStreamManager.Events.MemoryStreamCreated(Guid, String, Int64, Int64): Using member 'System.Diagnostics.Tracing.EventSource.WriteEvent(Int32, Object[])' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. EventSource will serialize the whole object graph. Trimmer will not safely handle this case because properties may be trimmed. /_/src/Events.cs(235,21): Trim analysis warning IL2026: Microsoft.IO.RecyclableMemoryStreamManager.Events.MemoryStreamDiscardBuffer(Guid, String, RecyclableMemoryStreamManager.Events.MemoryStreamBufferType, RecyclableMemoryStreamManager.Events.MemoryStreamDiscardReason, Int64, Int64, Int64, Int64, Int64, Int64): Using member 'System.Diagnostics.Tracing.EventSource.WriteEvent(Int32, Object[])' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. EventSource will serialize the whole object graph. Trimmer will not safely handle this case because properties may be trimmed.

Adding [RequiresUnreferencedCodeAttribute] to all methods calling this.WriteEvent would properly forward the trim warnings, not causing the library to produce trim warnings.

[benmwatson]

Thanks for reporting this. I will try to look at this and a few other issues for RMS in the next couple of weeks, unless you'd like to submit a PR.

[zeroskyx]

Hi @benmwatson,

thanks for the feedback. I've opened a PR that uses a new primitive available in .NET 8.0 that fixes the problem with the potentially dynamic types.

I've added net8.0 to the project types -- you might have to add that to the nuget build pipeline.

All the best
-Simon

[maxkatz6]

You can set <EventSourceSupport>false</EventSourceSupport> in your project, if you don't need event source support. These methods will be trimmed.
But ideally this library should be trimmer compatible on its own.

[benmwatson]

After a long break, finally getting back to this. There doesn't appear to avoid propagating warnings up to public callers with [RequiresUnreferencedCode], or I need to drop net6.0 support. Either way, this is a breaking change.

I'm going to open a separate PR to remove explicit net6.0 support and make net8.0 the new baseline. Older frameworks will continue to be supported via netstandard2.0 and netstandard2.1. There will be a couple of minor perf regressions for net6.0 because of some missing APIs.

[maxkatz6]

@benmwatson I would recommend adding IsTrimmable and IsAotCompatible properties to the new .NET 8 target framework. This will ensure projects doesn't have other relevant warnings and will mark assembly as trimmable in the eyes of compiler.