Bad array indexing is considered deadly

[Moritz Maxeiner via Digitalmars-d]

On Wednesday, 31 May 2017 at 20:23:21 UTC, Nick Sabalausky 
(Abscissa) wrote:
> On 05/31/2017 03:17 PM, Moritz Maxeiner wrote:
>> in general you have to assume that the index *being* out of 
>> bounds is itself the *result* of *already occurred* data 
>> corruption;
> Of course not, that's absurd. Where do people get the idea that 
> out-of-bounds *implies* pre-existing data corruption?

You assume something I did not write. What I wrote is that the 
runtime cannot *in general* (i.e. without further information 
about the semantics of your specific program) assume that it was 
*not* preexisting data corruption.

> Most of  the time, out-of-bounds comes from a bug (especially 
> in D, what with all of its safeguards).

Unfortunately the runtime has no way to know *if* the out of 
bounds comes from a bug or a data corruption, which was my point; 
only a human can know that. What is the most likely culprit is 
irrelevant for the default behaviour, because as long as it 
*could* be data corruption, the runtime cannot by default assume 
that it is not; that would be unsafe.

>
> Sure, data corruption is one possible cause of out-of-bounds, 
> but data corruption is one possible cause of *ANYTHING*. So 
> just to be safe, let's just abort on all exceptions, and upon 
> everything else for that matter.

No, abort on Errors where the runtime cannot know if data 
corruption has already occured, i.e. the program is in an 
undefined state. If you, as the programmer, know that it is safe, 
you have to code that in.