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Subject: |
24.0.50; `bounds-of-thing-at-point' returns (N . N) for `comment' |
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Date: |
Thu, 12 May 2011 17:46:33 -0700 |
emacs -Q
Put point at position 3061 in file thingatpt.el (i.e., just before the
`a' of `condition-case').
M-: (bounds-of-thing-at-point 'comment)
returns (3061 . 3061), which represents an empty thing, "".
This happens at most positions, probably all positions outside a comment.
The code should handle this kind of case correctly (in other respects it
seems to work OK for comments).
The problem is that there is no `beginning-op' or `end-op' and all of
the calls to `forward-thing' (with 1 and -1) do not move point at all,
and return nil. So the code falls through to the end:
(let ((end (point))
(real-beg
(progn
(funcall
(or (get thing 'beginning-op)
(lambda () (forward-thing thing -1))))
(point))))
;; real-beg = end = (point). Result is (cons 3061 . 3061).
(if (and real-beg end (<= real-beg orig) (<= orig end))
(cons real-beg end)))
`bounds-of-thing-at-point' should foresee such a case (that `forward-THING' does
nothing). IOW, it should of course be fixed for this problem.
But it sounds like `forward-comment' should also be fixed so that it acts like
other `forward-THING' functions, and not just be a no-op when outside a comment.
In GNU Emacs 24.0.50.1 (i386-mingw-nt5.1.2600)
of 2011-05-10 on 3249CTO
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (4.5) --no-opt --cflags
-Ic:/build/include'
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Subject: |
RE: bug#8667: 24.0.50; `bounds-of-thing-at-point' returns (N . N) for `comment' |
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Date: |
Thu, 19 May 2011 10:12:22 -0700 |
> 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.
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