[matheusmoreira]

I'm dealing with the exact same issues right now in my project, this post is very enlightening.

> But suppose we want an empty (length zero) slice.

So is there an actual rationale for this? I've written the memory allocator and am in the process of developing the foreign interface. I've been wondering if I should explicitly support zero length allocations. Even asked this a few times here on HN but never got an answer. It seems to be a thing people sort of want but for unknown reasons.

[anderskaseorg]

It is extremely common to have a collection that might or might not be empty at runtime, and we don’t want to force every programmer who allocates a slice to manually write an alternate code path for the empty case.

[matheusmoreira]

Are memory blocks collections though? An empty list or table makes intuitive sense. Does a zero sized memory block make sense? I'm having trouble understanding that. If the memory has size zero, then by definition there is nothing to point to, nothing whose address can be taken.

I definitely see the benefits of well-defined arithmetic on null pointers. As a data type though it seems to me that any pointer could be a zero sized allocation.

[anderskaseorg]

When you allocate memory for an empty array with malloc(num * size) where num == 0, you get a zero-sized memory block. As discussed in the article, representing this with a null pointer causes problems, because that results in undefined behavior in memcpy (despite asking it to copy 0 bytes). So we want it to be a real memory block that can be safely passed to free().