I was looking at this question How do I read from a pointer that looks like "process name" + address? and noticed that the OP had posted an answer in the body. Should this question be closed, flagged, or just left as is? The OP has obviously abandoned the question.
Whenever I see an answer in question, I just remove that part and re-paste it to the community wiki answer. You can warn OP about that in a comment, so they know what to do next time they solve their question
The other alternative is to vote to close as "too localised". If the OP isn't interested in the question any more and it has no other answers then it's not really going to be making the internet a better place.
At tex.stackexchange, I have flagged about a dozen questions of this sort with the custom text "Questioner edited his/her own answer into the question". (IMO, this is the complement to "not an answer".) I also always leave a comment suggesting that the OP should cut-and-paste his solution into a separate answer (which might earn additional reputation). If the OP doesn't react, eventually a moderator will cut-and-paste the solution into a community wiki answer.