In this case, I am more inclined now for `var->offset_reservation.index` since the raison d'etre of `proper_offset` is to perform the check above, and the assignment would be giving it a secondary purpose.
That, yeah. Not to mention that the whole point of packoffset() is to say "place the variable exactly here".
There are certainly similar situations where I think it doesn't matter, though.
Error reporting of the offset reservation overlaps could differ slightly though.
Which is probably another reason we should do it this way; we don't want to report an overlap if the user didn't actually create one per se.