We recently had a situation on ru.SO, where a new user had posted 22 answers in 2 hours, 17 of which were copy-pasted from comments under the corresponding questions. Most of them were copied verbatim, none of the answers were made 'community wiki', and no attribution was provided.
To my surprise, the mod team decided to not do anything about it, and our meta community doesn't seem to have a clear consensus if something needs to be done or not.
But this is not what this question is about.
This sparked a discussion. Does copying another user's comment into an answer require attribution, as per CC BY-SA?
More broadly, if you copy content made by another user into your own post on SO (as opposed to posting it on an unrelated site), do you have to provide attribution or not?