bug#8667: 24.0.50; `bounds-of-thing-at-point' returns (N . N) for `comment'

[Drew Adams]

> Installed a patch along the lines of what you suggested.

No, I don't think you did.  I just downloaded the latest thingatpt.el.  There is
no fix AFAICT.

There are still the two problems reported for `bounds-of-thing-at-point' in this
bug report: (1) it can return a cons with equal car and cdr (representing an
empty thing), (2) it can return a cons representing only whitespace, instead of
returning nil when there is no comment at point.


1. You did not filter out the case where (= beg real-end) or
(= real-beg end), so `bounds-of-thing-at-point' can still return a cons with
equal car and cdr.

You need to add these conditions to the tests:

(and beg real-end (<= beg orig) (<= orig real-end)
                  (/= beg real-end) ; <===== NEEDED
                  (cons beg real-end))
...

(and real-beg end (<= real-beg orig) (<= orig end)
                  (/= real-beg end) ; <===== NEEDED
                  (cons real-beg end))


2. It is still the case that (bounds-of-thing-at-point 'comment) can return a
cons representing only whitespace, when called outside a comment.  Put point
here, for instance:

(defun bounds-of-thing-at-point...
       ^

It should always return nil, never return a cons, when there is no comment at
point.  This is a `b-o-t-a-p' bug (not a `forward-comment' bug).  In turn, this
bug causes (thing-at-point 'comment) to return " " at such a location.