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bug#35600: [Patch]: Re: bug#35600: 27.0.50; uncomment-region fails corre
From: |
Alan Mackenzie |
Subject: |
bug#35600: [Patch]: Re: bug#35600: 27.0.50; uncomment-region fails correctly to reverse the action of comment-region. |
Date: |
Tue, 7 May 2019 08:59:53 +0000 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
Hello, Emacs.
On Mon, May 06, 2019 at 10:11:00 +0000, Alan Mackenzie wrote:
> In the master branch:
> With indent-tabs-mode t, and tab-width (say) 8, start off with the
> following two line of Emacs lisp:
> (if (null bs-state)
> (ignore)
> ^
> <tab>
> (the first of these lines being indented by four spaces, the second by a
> <tab>).
> Mark the two lines, and execute M-x comment-region. We get this:
> ;; (if (null bs-state)
> ;; (ignore)
> ^
> <tab>
> (where all the space is space characters except for the <tab> just
> before "(ignore)").
> Now execute M-x uncomment-region. This should restore the region to
> what it started as. Instead one gets:
> (if (null bs-state)
> (ignore)
> ^^^^ ^
> SPCs <tab>
> , there now being four spurious spaces before the <tab> preceding
> "(ignore)". This is a bug.
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> In uncomment-region-default-1, the variable `spt' gets set to the result
> of comment-search-forward, the ";" at the beginning of the comment on
> the current line. The function then narrows to between `spt' and BO
> next line.
> In this narrowed region, the function removes the comment starter.
> Because of the narrowing, it cannot take any account of the spaces at
> the start of the line.
> Possibly, uncomment-region needs to be amended so that that narrowing
> includes any space preceding the comment starter, and that space gets
> properly handled.
Here is a patch which fixes the bug a little differently. After removing
a comment starter, if there are obtrusive spaces left before a <tab>,
they get removed:
diff --git a/lisp/newcomment.el b/lisp/newcomment.el
index 9d919ccbbe..ab2be080a3 100644
--- a/lisp/newcomment.el
+++ b/lisp/newcomment.el
@@ -1001,7 +1001,15 @@ uncomment-region-default-1
(re-search-forward sre (line-end-position) t))
(replace-match "" t t nil (if (match-end 2) 2 1)))))
;; Go to the end for the next comment.
- (goto-char (point-max))))))
+ (goto-char (point-max)))
+ ;; Remove any obtrusive spaces left preceding a tab at `spt'.
+ (when (and (eq (char-after spt) ?\t) (eq (char-before spt) ? )
+ (> tab-width 0))
+ (save-excursion
+ (goto-char spt)
+ (let* ((fcol (current-column))
+ (slim (- (point) (mod fcol tab-width))))
+ (delete-char (- (skip-chars-backward " " slim)))))))))
(set-marker end nil))
(defun uncomment-region-default (beg end &optional arg)
--
Alan Mackenzie (Nuremberg, Germany).