Re: address@hidden: Re: re-builder bug(s)]

[Richard Stallman]

    This happens in line 646 and following of re-builder.el.
    `reb-update-overlays' `re-search'es the buffer and checks whether the
    match is empty, otherwise it updates the match-overlays:

            (if (= 0 (length (match-string 0)))
                (error "Empty regular expression!"))

    So, this "bug" seems to be intentional. I wouldn't know what to do,
    anyways. How do you highlight an empty string?

You could put the cursor there and make it look funny, maybe.
Or use an overlay with an after-string.

Or just display a message in the minibuffer to explain the situation.