Await using declarations in top scope is not supported

[yyjdelete]

Input code

    public async Task XXX1(IAsyncDisposable a)
    {
        await using var b = a;
        a = null;
        Console.WriteLine(b);
    }
    public async Task XXX3(IAsyncDisposable a)
    {
        await using (var b = a)
        {
            a = null;
            Console.WriteLine(b);
        }
    }

Erroneous output

Seems roslyn will produce different IL for them, and the first one will not be recognized as await using.

public async Task XXX1(IAsyncDisposable a)
{
	IAsyncDisposable b = a;
	object obj = null;
	int num = 0;
	try
	{
		a = null;
		Console.WriteLine(b);
		num = 1;
	}
	catch (object obj2)
	{
		obj = obj2;
	}
	if (b != null)
	{
		await b.DisposeAsync();
	}
	object obj3 = obj;
	if (obj3 != null)
	{
		ExceptionDispatchInfo.Capture((obj3 as Exception) ?? throw obj3).Throw();
	}
	if (num != 1)
	{
	}
}

public async Task XXX3(IAsyncDisposable a)
{
	await using IAsyncDisposable b = a;
	a = null;
	Console.WriteLine(b);
}

Details

• Product in use: ILSpy
• Version in use: 7.0.0.6433-preview3