bug#24914: 24.5; isearch-regexp: wrong error message

[Drew Adams <drew.adams@oracle.com>]

> > 3. C-M-s \(.\|^J\)\{,40000\}
> > That shows the error message: [incomplete input],
> > which is wrong, IMO.
> 
> The reason it doesn't work is because the number of repitions
> is limited to 32767 (#x7fff).

Yet another case for adding bignums to Emacs Lisp?
I imagine someone will answer that there needs to be
a limit.

In that case, can we not use something larger?
Could we use the value of `most-positive-fixnum'?

> Obviously that should be documented in the manual.

Yes, please.

> As to the error message itself, there isn't really a way
> to distinguish between incomplete and invalid input,

We do that in some places in the code.  Some code
parses the regexp, and that code must know (or be
able to know) both that the regexp is not incomplete
and that the numeral given for the number of repetitions
is too large.

> so the only thing I can see to do
> is to change the message to [incomplete or invalid input].

I suppose that's better than [incomplete], but it doesn't
really help users very much.

Can we please do that but keep this bug open, hoping that
someone will someday provide a real fix?