Making alloca more safe

[Walter Bright]

Tomas Lindquist Olsen wrote:
> You sure got all the answers...

I had it beaten into my head by people who had 50 years of experience 
designing reliable airliners - what worked and what didn't work.

The consensus on what constitutes best practices for software 
reliability is steadily improving, but I still think the airliner 
companies are more advanced in that regard.

Even your car has a dual path design (for the brakes)!