Is “delete p; p = NULL(nullptr);” an antipattern?

Question

Searching something on SO, I stumbled across this question and one of the comments to the most voted answer (the fifth comment to that most voted answer) suggests that del

Answer 1

I recommend doing so.

• Obviously, it's valid in a context where NULL is a valid value of the pointer. This, of course, means if it's used in other places, it must be checked.
• Even if the pointer may, technically, not be NULL, it does help in real-world scenarios when customers send you a crash dump. If it's NULL and it's not supposed to be (and it wasn't trapped in testing with the assert() that you should do), then it's easy to see that this is the problem - you'll crash at something like mov eax, [edx+4] or something, you'll see that edx is 0, and you know what the problem is. If, on the other hand, you don't NULL the pointer, but it is deleted, then all sorts of things may happen. It may work, it may crash immediately, it may crash later, it may show weird things - at this point, anything that happens is soft-non-deterministic.
• Defensive programming is King. That includes setting a pointer to NULL extraneously, even if you think you don't have to, and doing that extra NULL check in a few places even though you technically know it isn't supposed to happen.
• Even if you have the logic error of a pointer going through delete twice, it's better to not crash and handle it safely than to crash. That may mean you do that extra check, and you'll probably want to log that, or maybe even end the program gracefully, but it's not just a crash. Customers don't like that.

Personally, I use an inline function that takes the pointer as a reference and sets it to NULL.