Extra ILC warnings when PublishAOT=true on method already marked RequiresUnreferencedCode

[eerhardt]

Description

When Publishing AOT, I'm seeing extra warnings being emitted that clutter the warnings and confuse developers.

From what I can tell, the warnings are coming from:

runtime/src/libraries/Microsoft.Extensions.Logging.Configuration/src/LoggerProviderConfigurationExtensions.cs

Lines 25 to 29 in 2f3fcca

	[RequiresDynamicCode(RequiresDynamicCodeMessage)]
	[RequiresUnreferencedCode(TrimmingRequiresUnreferencedCodeMessage)]
	public static void RegisterProviderOptions<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] TOptions, TProvider>(IServiceCollection services) where TOptions : class
	{
	services.TryAddEnumerable(ServiceDescriptor.Singleton<IConfigureOptions<TOptions>, LoggerProviderConfigureOptions<TOptions, TProvider>>());

ServiceDescriptor.Singleton has a [DAM] attribute for the constructor of the 2nd generic arg:

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

Line 302 in 2f3fcca

public static ServiceDescriptor Singleton<TService, [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] TImplementation>()

and LoggerProviderConfigureOptions has RDC and RUC on its ctor:

runtime/src/libraries/Microsoft.Extensions.Logging.Configuration/src/LoggerProviderConfigureOptions.cs

Lines 14 to 16 in 2f3fcca

	[RequiresDynamicCode(LoggerProviderOptions.RequiresDynamicCodeMessage)]
	[RequiresUnreferencedCode(LoggerProviderOptions.TrimmingRequiresUnreferencedCodeMessage)]
	public LoggerProviderConfigureOptions(ILoggerProviderConfiguration<TProvider> providerConfiguration)

However, these warnings shouldn't be emitted because RegisterProviderOptions has RDC and RUC attributes. So I should only be getting the warnings from my call to RegisterProviderOptions.

cc @MichalStrehovsky @vitek-karas

Reproduction Steps

Using 7.0-rc1, dotnet publish -c Release -r win-x64 the following app:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net7.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <PublishAOT>true</PublishAOT>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.Extensions.Hosting" Version="7.0.0-rc.1.22426.10" />
  </ItemGroup>
</Project>

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging.Configuration;
using Microsoft.Extensions.Logging.Console;

LoggerProviderOptions.RegisterProviderOptions<ConsoleLoggerOptions, ConsoleLoggerProvider>(new ServiceCollection());

Expected behavior

I should only get warnings for my program's call to RegisterProviderOptions.

Actual behavior

Along with the expected warnings from my code, I'm getting these extra warnings in the publish output:

ILC : Trim analysis warning IL2026: Microsoft.Extensions.DependencyInjection.ServiceDescriptor.Singleton<IConfigureOptions`1<ConsoleLoggerOptions>,LoggerProviderConfigureOptions`2<ConsoleLoggerOptions,ConsoleLoggerProvider>>(): Using member 'Microsoft.Extensions.Logging.Configuration.LoggerProviderConfigureOptions`2<ConsoleLoggerOptions,ConsoleLoggerProvider>.LoggerProviderConfigureOptions`2<ConsoleLoggerOptions,ConsoleLoggerProvider>(ILoggerProviderConfiguration`1<ConsoleLoggerProvider>)' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. TOptions's dependent types may have their members trimmed. Ensure all required members are preserved. [C:\Users\eerhardt\source\repos\WorkerService12\WorkerService12\WorkerService12.csproj]
ILC : Trim analysis warning IL2026: Microsoft.Extensions.DependencyInjection.ServiceDescriptor.Describe<IConfigureOptions`1<ConsoleLoggerOptions>,LoggerProviderConfigureOptions`2<ConsoleLoggerOptions,ConsoleLoggerProvider>>(ServiceLifetime): Using member 'Microsoft.Extensions.Logging.Configuration.LoggerProviderConfigureOptions`2<ConsoleLoggerOptions,ConsoleLoggerProvider>.LoggerProviderConfigureOptions`2<ConsoleLoggerOptions,ConsoleLoggerProvider>(ILoggerProviderConfiguration`1<ConsoleLoggerProvider>)' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. TOptions's dependent types may have their members trimmed. Ensure all required members are preserved. [C:\Users\eerhardt\source\repos\WorkerService12\WorkerService12\WorkerService12.csproj]

Regression?

I'm not sure. Probably not.

Known Workarounds

No response

Configuration

No response

Other information

No response

[agocke]

@tlakollo Let's work on this as soon as packaging is done and ready for linker in runtime.

[eerhardt]

@tlakollo - any update on this? We'd like to get to 0 warnings in a very basic ASP.NET app soon.

[vitek-karas]

I'll look into this.

[vitek-karas]

This is a known problem (don't think we have an issue yet) which we've been discussing for a while. In general the NativeAOT compiler's handling of warnings from DAM annotation of generic arguments is problematic. It performs the DAM validation in places where it should not (which is most likely the reason for the extra warnings you see here) and it also reports these warnings as originating from wrong places (doesn't seem to be hit by this code).

I've discussed this with @MichalStrehovsky and we need to modify how the compiler handles DAM on generics. The broad idea is:

• Avoid analyzing generic instantiations which are caused by instantiating method bodies or types - basically if the original IL is something like MyGeneric<!0> then we should only analyzer that, and not any specific MyGeneric<Foo> which is produced by the compiler during instantiation of generics.
• Instead of relying on dependency nodes, try to analyze generic instantiations from data flow as much as possible (since there we can provide the correct message origin)

Unfortunately what this means is that it's not a simple fix and thus will take some time. I guess we (read @vitek-karas 😉) need to prioritize this work.

[DamianEdwards]

I'm hitting this warning now with the code produced by the new project template so it seems this is going to be on the critical path to getting past our stage 1 goals (create a new project from this template with native AOT enabled and get now warnings).

[eerhardt]

and thus will take some time

Any idea how long? Is it something that could make it into 8.0-preview2? That's when we are targeting getting a basic ASP.NET app published for AOT without any warnings.