[kinkdr]

Why is it UB?

Let's say head value is "10" and the memory at "10" is {..., next: "10"}

After the first iteration we will have:

Head: "10" Next: "10" Temp: "10"

With "10" pointing to freed memory. But why do we care? We are not dereferencing it, are we?

(I think I am missing something very obvious)

[jacquesgt]

I think you’re missing the fact that "There are a lot of rules you need to be aware of that are not naturally-occurring results of the fundamentals."

[kinkdr]

I was indeed. Thanks for the insight!

[Arnavion]

Because the standard says even comparing a dangling pointer is UB, which was haberman's point about the standard being non-intuitive.

[kinkdr]

Thanks. I wasn't aware of that. I stand corrected!!