Re: Cleaning up array_in()

I wrote:
> This comes out when you write something like '{foo"bar"}', and I'd
> say the choice of message is not great. On the other hand, it's
> consistent with what you get from '{"foo""bar"}', and if we wanted
> to change that too then some tweaking of the state machine in
> ReadArrayStr would be required (or else modify ReadArrayToken so
> it doesn't return instantly upon seeing the second quote mark).
> I'm not sure that this is worth messing with.

After further thought I concluded that this area is worth spending
a little more code for. If we have input like '{foo"bar"}' or
'{"foo"bar}' or '{"foo""bar"}', what it most likely means is that
the user misunderstood the quoting rules. A message like "Unexpected
array element" is pretty completely unhelpful for figuring that out.
The alternative I was considering, "Unexpected """ character", would
not be much better. What we want to say is something like "Incorrectly
quoted array element", and the attached v12 makes ReadArrayToken do
that for both quoted and unquoted cases.

I also fixed the obsolete documentation that Alexander noted, and
cleaned up a couple other infelicities (notably, I'd blindly written
ereport(ERROR) in one place where ereturn is now the way).

Barring objections, I think v12 is committable.

regards, tom lane