RequiresUnreferencedCode does not seem to work at the class level

[yaakov-h]

Given the following code, with .NET SDK 6.0.100-preview.5.21302.13:

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Reflection;

namespace DemoTrimmedApp
{
    class Program
    {
        static void Main()
        {
            foreach (var type in SuperHandyReflectionUtil.GetTypeNames())
            {
                Console.WriteLine(type);
            }
        }
    }

    class EligibleForTrimming { }

    class AlsoEligibleForTrimming { }

    [RequiresUnreferencedCode("pretending for a moment that we do something more dynamic")]
    class SuperHandyReflectionUtil
    {
        public static IEnumerable<string> GetTypeNames()
        {
            foreach (var type in Assembly.GetCallingAssembly().GetTypes())
            {
                yield return type.Name;
            }
        }
    }
}

and given this simple project file:

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

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
    <PublishTrimmed>true</PublishTrimmed>
    <PublishSingleFile>true</PublishSingleFile>
  </PropertyGroup>

</Project>

I would expect that there would be no warnings from within SuperHandyReflectionUtil about using reflection, and a warning in Program.Main that I am calling code that has the RequiresUnreferencedCode attribute.

Instead, I get the following singular warning, which is the exact same warning I get when RequiresUnreferencedCode is not present at all (i.e when deleted or commented out):

warning IL2026: Using method 'System.Reflection.Assembly.GetTypes()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. Types might be removed.

It would appear that even though the attribute has AttributeTargets.Class, it only has an effect when applied to every individual method or constructor within said class that requires it.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[vitek-karas]

This is a dupe of dotnet/linker#1742. It's currently being worked on.