Description

For an assembly that is not strong-named, AssemblyName.FullName doesn't show PublicKeyToken=null portion when the AssemblyName instance is returned from AssemblyName.GetAssemblyName. This is a regression from .NET 6.

This regression caused one of PowerShell test to fail, which was disabled for the time being:
https://github.com/PowerShell/PowerShell/blob/master/test/xUnit/csharp/test_NativeInterop.cs#L20

However, after the assembly is loaded, the AssemblyName instance returned from Assembly.GetName() works as expected (and as before).

Reproduction Steps

1. Create a non-strong-named assembly, here is the code for doing that:

   using System;
   using System.Collections.Generic;
   using System.IO;
   using System.Linq;
   using System.Reflection;
   using System.Runtime.InteropServices;
   using System.Runtime.Loader;
   using System.Management.Automation;
   
   using Microsoft.CodeAnalysis;
   using Microsoft.CodeAnalysis.CSharp;
   using Microsoft.CodeAnalysis.Emit;
   using Microsoft.CodeAnalysis.Text;
   
   namespace MyApp // Note: actual namespace depends on the project name.
   {
       public class Program
       {
           public static void Main(string[] args)
           {
               string tempDir = Path.Combine(Path.GetTempPath(), "TestLoadNativeInMemoryAssembly");
               string testDll = Path.Combine(tempDir, "test.dll");
   
               if (!File.Exists(testDll))
               {
                   Directory.CreateDirectory(tempDir);
                   bool result = CreateTestDll(testDll);
               }
   
               var asmName = AssemblyName.GetAssemblyName(testDll);
   
               Console.WriteLine($"Assembly: {testDll}");
               Console.WriteLine($"Assembly FullName: {asmName.FullName}");
           }
   
           private static bool CreateTestDll(string dllPath)
           {
               var parseOptions = CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.Latest);
               var compilationOptions = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary);
   
               List<SyntaxTree> syntaxTrees = new();
               SourceText sourceText = SourceText.From("public class Utt { }");
               syntaxTrees.Add(CSharpSyntaxTree.ParseText(sourceText, parseOptions));
   
               var refs = new List<PortableExecutableReference> { MetadataReference.CreateFromFile(typeof(object).Assembly.Location) };
               Compilation compilation = CSharpCompilation.Create(
                           Path.GetRandomFileName(),
                           syntaxTrees: syntaxTrees,
                           references: refs,
                           options: compilationOptions);
   
               using var fs = new FileStream(dllPath, FileMode.CreateNew, FileAccess.ReadWrite, FileShare.None);
               EmitResult emitResult = compilation.Emit(peStream: fs, options: null);
               return emitResult.Success;
           }
       }
   }

2. Running the above code with .NET 7-preview.2, you will see the , PublicKeyToken=null part is missing from the Assembly FullName.

Expected behavior

The , PublicKeyToken=null is present, like in .NET 6 and prior .NET versions.

Actual behavior

The , PublicKeyToken=null portion is missing.

Here is what you will see in PowerShell that built with .NET 7-preview.2:

PS:20> [System.Reflection.AssemblyName]::GetAssemblyName("C:\arena\tmp\abc.dll").FullName
qkoexti2.h5p, Version=0.0.0.0, Culture=neutral

PS:15> $t = Add-Type -Path C:\arena\tmp\abc.dll -PassThru
PS:16> $t.Assembly.FullName
qkoexti2.h5p, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null
PS:17> $n = $t.Assembly.GetName()
PS:18> $n.FullName
qkoexti2.h5p, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null

Here is the .NET version:

PS:23> [System.Environment]::Version

Major  Minor  Build  Revision
-----  -----  -----  --------
7      0      0      -1

Regression?

Yes. It's a regression to .NET 6 and prior versions.

Known Workarounds

No response

Configuration

No response

Other information

No response