Unskip NestedCatch_DuplicateLocal_Level2

[JoeRobich]

In the move from running against .NET 10 to .NET 11 preview, the following async runtime test failure was encountered:

CodeGenAsyncEHTests.NestedCatch_DuplicateLocal_Level2

System.NullReferenceException : Object reference not set to an instance of an object.



Stack trace
   at C.M2(String caller, Exception ex) in :line 64
   at C.M1(Boolean catchFirst1, Boolean catchFirst2) in :line 44
   at C.Main() in :line 14
   at C.<Main>()
   at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)

[333fred]

his appears to be a runtime-async bug in .NET 11 Preview 6. I reduced the test to the following file-based app:

#:property Features=runtime-async=on
#:property LangVersion=preview
#:property Optimize=true
#:property NoWarn=SYSLIB5007;CA2252

using System;
using System.Threading.Tasks;

Test.Run();

class Test
{
    public static void Run()
    {
        new Test().M().GetAwaiter().GetResult();
    }

    static bool Filter(Exception ex, bool result)
    {
        Console.WriteLine(ex.Message);
        return result;
    }

    async Task M()
    {
        try
        {
            throw new Exception("outer");
        }
        catch (Exception ex) when (Filter(ex, false))
        {
            await Print(ex);
        }
        catch (Exception ex) when (Filter(ex, true))
        {
            try
            {
                throw new Exception("inner");
            }
            catch (Exception ex2) when (Filter(ex2, false))
            {
                await Print(ex);
                await Print(ex2);
            }
            catch (Exception ex2) when (Filter(ex2, true))
            {
                try
                {
                    throw new Exception();
                }
                catch
                {
                    await Print(ex);
                    await Print(ex2);
                }
            }
        }
    }

    static async Task Print(Exception ex)
    {
        await Task.Yield();
        Console.WriteLine(ex.Message);
    }
}

With global.json pinned to SDK 10.0.301, this exits successfully:

$ DOTNET_RuntimeAsync=1 dotnet run 84791.cs
outer
outer
inner
inner
outer
inner

With global.json pinned to SDK 11.0.100-preview.6.26359.118, the same command fails because the second captured exception becomes null:

$ dotnet run 84791.cs
outer
outer
inner
inner
outer
Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.
   at Test.Print(Exception ex) in 84791.cs:line 63
   at Test.M() in 84791.cs:line 54

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