catch(...) and forced unwind

[Mark Mitchell]

> I want to be *able* to say, "don't throw any cancellation exceptions
> at me except where I explicitly call pthread_whatever_its_called (the
> one which just throws if there's a cancellation pending and does
> nothing otherwise)".  There's nothing wrong with your other modes,
> but IMO the mode I'm describing would provide the safest route to
> integrate library source code into a threaded app.

Yes, that is a 3rd mode: a fully synchronous model.

That would also be a POSIX threads extension; essentially, this would be
the deferred cancellation model, except that pthread_testcancel would be
the only cancellation point.

I think that, too, is a reasonable mode.

-- 
Mark Mitchell <mark@codesourcery.com>
CodeSourcery, LLC