ILC IL3050 False positives when building with PublishAot

[hwoodiwiss]

Description

Firstly, sorry for the bad/vague name. I'm not sure what's triggering this.

When building targeting NativeAOT, I have come across a case in which I am hitting what I beleive is a false positive analyzer warning from ILC/ILLink while generating native code.

I'm seeing an analyzer warning:

ILC : AOT analysis warning IL3050: GitHub.Models.PullRequestReview.<GetFieldDeserializers>b__58_0(IParseNode): Using member 'System.Enum.GetValues(Type)' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. It might not be possible to create an array of the enum type at runtime. Use the GetValues<TEnum> overload or the GetValuesAsUnderlyingType method instead. [R:\source\repos\IL3050FalsePositiveRepro\IL3050FalsePositiveRepro.csproj]

However, I can't see how the referenced method is using System.Enum.GetValues(Type), either directly, nor indireclty.

This is consistent across both SDK 8.0.201 and SDK 9.0.100-preview.1.24101.2

Reproduction Steps

I've created a minimal reproduction here: https://github.com/hwoodiwiss/IL3050FalsePositiveRepro

The behaviour exhibited in the above repo is consistent across methods in Kiota generated APIs that use enums.

Expected behavior

No IL3050 warnings. I can't see anywhere that a method marked with RequiresUnreferencedCode is called in the call chain.

Actual behavior

ILC : AOT analysis warning IL3050 during builds, which now causes build errors when TreatWarningsAsErrors is enabled with the .NET 9 previews.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

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Issue Details

---

Description

When building targeting NativeAOT, I have come across a case in which I believe I am hitting a false positive analyzer warning from ILC while generating native code.

I'm seeing an analyzer warning:

ILC : AOT analysis warning IL3050: GitHub.Models.PullRequestReview.<GetFieldDeserializers>b__58_0(IParseNode): Using member 'System.Enum.GetValues(Type)' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. It might not be possible to create an array of the enum type at runtime. Use the GetValues<TEnum> overload or the GetValuesAsUnderlyingType method instead. [R:\source\repos\IL3050FalsePositiveRepro\IL3050FalsePositiveRepro.csproj]

However, I can't see how the referenced method is using System.Enum.GetValues(Type), either directly, nor indireclty.

This is consistent across both SDK 8.0.201 and SDK 9.0.100-preview.1.24101.2

Reproduction Steps

I've created a minimal reproduction here: https://github.com/hwoodiwiss/IL3050FalsePositiveRepro

The behaviour exhibited in the above repo is consistent across, methods in Kiota generated APIs that use enums.

Expected behavior

No IL3050 warnings. I can't see anywhere that a method marked with RequiresUnreferencedCode is called in the call chain.

Actual behavior

ILC : AOT analysis warning IL3050 during builds, which now causes build errors when TreatWarningsAsErrors is enabled with the .NET 9 previews.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Author:	hwoodiwiss
Assignees:	-
Labels:	area-NativeAOT-coreclr
Milestone:	-

[Sergio0694]

Have you tried using https://github.com/MichalStrehovsky/sizoscope to investigate the root path for that method call?

[hwoodiwiss]

Have you tried using https://github.com/MichalStrehovsky/sizoscope to investigate the root path for that method call?

Ah, great shout, I'll have a look and get back to you.

[vitek-karas]

The problem is this method:
https://github.com/microsoft/kiota-abstractions-dotnet/blob/main/src/serialization/IParseNode.cs

It adds the DynamicallyAccessedMembers(All) annotation onto the T which is the enum type. This will mean the compiler need to pull in (and consider callable) all methods of the T and its base types, one of which is System.Enum which in turn has the GetValues(Type) method. Since the compiler needs to consider this method callable, it checks annotations on it, and it has RequiresDynamicCode and thus it produces IL3050.

[hwoodiwiss]

The problem is this method: https://github.com/microsoft/kiota-abstractions-dotnet/blob/main/src/serialization/IParseNode.cs

It adds the DynamicallyAccessedMembers(All) annotation onto the T which is the enum type. This will mean the compiler need to pull in (and consider callable) all methods of the T and its base types, one of which is System.Enum which in turn has the GetValues(Type) method. Since the compiler needs to consider this method callable, it checks annotations on it, and it has RequiresDynamicCode and thus it produces IL3050.

That makes a lot of sense. Thanks for the explanation. I'll close this and open an issue over there, I think this should be able to be reduced to just DynamicallyAccessedMembers(NonPublicFields | PublicFields) based on current usage, which should then fix the issue, as we're only interested in the names and values of the Enum types.

Closing this, as the issue isn't here.

Thank you both.