> I don't think I understand, but it sounds like this is a reason why
> y-or-n-p should save match-data...
Here we go again:
All functions destroy the match-data except for a few rare exceptions,
which are simple functions doing little work.
> Is there any reason not to let y-or-n-p save match data?
If you think y-or-n-p deserves saving the match-data then pretty much
all other functions deserve that change as well. And since
save-match-data is somewhat costly, it would imply a singificant
PS: Worse yet: during y-or-n-p, the buffer might be completely changed
by the code run asynchronously, so the "saved" match data may not even
have any meaning any more.