Bad array indexing is considered deadly

[Moritz Maxeiner via Digitalmars-d]

On Wednesday, 31 May 2017 at 23:50:07 UTC, Timon Gehr wrote:
>
> No, it is perfectly safe, because the language does not 
> guarantee any specific behavior in case memory is corrupted.

The language not guaranteeing a specific behaviour on memory 
corruption does not imply that assuming a bug was not caused by 
memory corruption is safe.

> Therefore the language can /always/ assume that there is no 
> memory corruption.

That is also not implied.

>
>>> One  does not require the other.
>> 
>> Correct, but the runtime has to be safe in the *general* case, 
>> so it *must* assume the worst in case of a bug.
>
> Software has bugs. The runtime has no business claiming that 
> the scope of any particular bug is the entire service.

It absolutely has the business of doing exactly that as long as 
you, the programmer, do not tell it otherwise; which you can do 
and is your job.

> The practical outcomes of this design are just silly. Data is 
> lost, services go down, etc. When in doubt, the software should 
> just do what the programmer has written. It is not always 
> correct, but it is the best available proxy of the desirable 
> behavior.

When in doubt about memory corruption, the closest enclosing 
scope that will get rid of the memory corruption must die. The 
current behaviour achieves that in many cases.