Subject: bug#28428: comment-search-backward with no comments

From: Stefan Monnier <[email-masked]>
Date: Fri, 22 Sep 2017 12:40:58 -0400

>    (if (not (re-search-backward comment-start-skip limit t))
> -      (unless noerror (error "No comment"))
> +      (progn
> +        (goto-char limit)
> +        (unless noerror (error "No comment")))

That looks fine, thank you.  But I think the simpler patch below works
as well:

    diff --git a/lisp/newcomment.el b/lisp/newcomment.el
    index be6dbe3a4c..e32966e596 100644
    --- a/lisp/newcomment.el
    +++ b/lisp/newcomment.el
    @@ -524,7 +524,7 @@ comment-search-backward
       ;; comment-search-backward is only used to find the comment-column (in
       ;; comment-set-column) and to find the comment-start string (via
       ;; comment-beginning) in indent-new-comment-line, it should be harmless.
    -  (if (not (re-search-backward comment-start-skip limit t))
    +  (if (not (re-search-backward comment-start-skip limit 'move))
           (unless noerror (error "No comment"))
         (beginning-of-line)
         (let* ((end (match-end 0))

I wonder if there's code out there that depends on this behavior, tho,
since AFAIK it's been behaving this way "forever".

        Stefan