Memory safe in D

[Steven Schveighoffer]

On Monday, 11 March 2024 at 08:16:13 UTC, Alex wrote:

> Is it expected behavior?
> Looks like it is not very safe approach and can lead to very 
> unpleasant memory errors...

So I know there are a lot of responses here, with a lot of 
discussion. But I don't think anyone has told you *why* D works 
this way.

The explanation is that D is expecting the memory hardware to 
fault when you dereference null. We know that this is not the 
case for all situations, but it is the case for all of D's normal 
usage modes (e.g. as user-code on standard operating systems).

Since the memory hardware *already supports this*, and is 
essentially free, D has deferred to that mechanism to guard 
against dereferencing null pointers. Not assuming this behavior 
means all dereferences of pointers/classes in `@safe` code would 
have to be instrumented with a check, slowing down the code 
significantly.

I consider null pointer faults to be annoying, but not nearly as 
bad as dangling pointer accesses. At least a null pointer 
*always* crashes when you access it.

-Steve