Bug description

The analyzer for VSTHRD010 is only checking for the existence of a main thread switching call above the offending code. But that's not sufficient if the code were to also switch to a worker thread after having switched to the main thread.

Repro steps

public async Task TestAsync(EnvDTE.DTE dte)
{
    await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync();
    await TaskScheduler.Default;
    var debugger = dte.Debugger;
}

Expected behavior

A VSTHRD010 warning should occur for this code because the 3rd line is not running on the main thread.

Actual behavior

No warning is produced.

• Version used:
• Application (if applicable):

Additional context

Add any other context about the problem here.