Re: EH in egcs

[mrs at wrs dot com (Mike Stump)]

Sorry, you don't understand C++'s requirements well enough to come up
with a design that will work.  The below is flawed.

One needs to have a stack of outstanding exceptions, and push/pop
elements of that stack at the right times (roughly speaking, push upon
first throw and pop upon exist of the last matching catch block).
__eh_{type,pc} and friends are then just the top elements of this
stack.

> From: hjl@lucon.org (H.J. Lu)
> To: law@cygnus.com
> Date: Sun, 26 Oct 1997 12:33:48 -0800 (PST)
> Cc: jason@cygnus.com, egcs@cygnus.com

> Although EH is much better than before, it still needs some improvement,
> especially what happens after the exception is caught. There are 2
> test cases which show the problem. That is nested throw/catch doesn't
> work. That is because __eh_value/__eh_type are used throughout
> EH and the new ones will override the old ones. I was wondering if
> we could do this in the catch region:

> Treat the caught exception as a local variable. That is make

> 	catch (type caught)
> 	{
> 	}

> equivalent to

> 	foo ()
> 	{
> 	  type caught;
> 	}

> Can we use __eh_value/__eh_type to make it to work? After that,
> caught will be handled just like any other local variables.
> If there is another exception thrown inside foo (), caught  
> will be cleared appropriately. Otherwise, it will be cleared
> when exception is out of scope.