From: "Andreas Röhler" <andreas.roehler@easy-emacs.de>
To: 21766@debbugs.gnu.org
Subject: bug#21766: 25.0.50; delete-trailing-whitespace sometimes deletes non-whitespace
Date: Tue, 27 Oct 2015 08:07:38 +0100 [thread overview]
Message-ID: <562F22BA.3050103@easy-emacs.de> (raw)
In-Reply-To: <CAAeL0SQ2X62q1YWEdTjj4Tkh6=mTRo6EmJmY-4F0fE0bgm8JyA@mail.gmail.com>
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On 27.10.2015 01:15, Juanma Barranquero wrote:
> On Tue, Oct 27, 2015 at 12:07 AM, Markus Triska <triska@metalevel.at
> <mailto:triska@metalevel.at>> wrote:
> >
> >
> > Steps to reproduce:
> >
> > 1) wget http://www.metalevel.at/ei/fault1.html
> >
> > 2) emacs -Q fault1.html
> >
> > 3) M-x delete-trailing-whitespace RET
> >
> > This removes several non-white-space characters, including the whole
> > line containing "and use it like" (line 83 in the original file),
>
> Apparently, the call to skip-syntax-backward is altering the match
> data. If you try this
>
> --- a/lisp/simple.el
> +++ b/lisp/simple.el
> @@ -609,7 +609,7 @@ delete-trailing-whitespace
> (start (or start (point-min))))
> (goto-char start)
> (while (re-search-forward "\\s-$" end-marker t)
> - (skip-syntax-backward "-" (line-beginning-position))
> + (save-match-data (skip-syntax-backward "-"
> (line-beginning-position)))
> ;; Don't delete formfeeds, even if they are considered
> whitespace.
> (if (looking-at-p ".*\f")
> (goto-char (match-end 0)))
>
>
> or, alternatively,
>
> @@ -609,11 +609,12 @@ delete-trailing-whitespace
> (start (or start (point-min))))
> (goto-char start)
> (while (re-search-forward "\\s-$" end-marker t)
> - (skip-syntax-backward "-" (line-beginning-position))
> - ;; Don't delete formfeeds, even if they are considered
> whitespace.
> - (if (looking-at-p ".*\f")
> - (goto-char (match-end 0)))
> - (delete-region (point) (match-end 0)))
> + (let ((end (match-end 0)))
> + (skip-syntax-backward "-" (line-beginning-position))
> + ;; Don't delete formfeeds, even if they are considered
> whitespace.
> + (if (looking-at-p ".*\f")
> + (goto-char end))
> + (delete-region (point) end)))
> ;; Delete trailing empty lines.
> (goto-char end-marker)
> (when (and (not end)
>
> it works.
First fix looks cleaner.
> Now, the question is, should skip-syntax-backward preserve the match
> data, or must delete-trailing-whitespace be coded defensively? The
> usual policy has been that code that needs the match data preserved
> should make sure itself that it is so.
Such a basic routine should preserve matches by its own virtue.
A couple of regression tests should pay here.
Thanks
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next prev parent reply other threads:[~2015-10-27 7:07 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-26 23:07 bug#21766: 25.0.50; delete-trailing-whitespace sometimes deletes non-whitespace Markus Triska
2015-10-27 0:15 ` Juanma Barranquero
2015-10-27 7:07 ` Andreas Röhler [this message]
2015-10-27 7:53 ` Juanma Barranquero
2015-10-27 8:05 ` martin rudalics
2015-10-27 8:12 ` Juanma Barranquero
2015-10-27 8:25 ` martin rudalics
2015-10-27 8:32 ` Juanma Barranquero
2015-10-27 9:01 ` Andreas Schwab
2015-10-27 9:16 ` Juanma Barranquero
2015-10-27 9:24 ` martin rudalics
2015-10-27 9:46 ` Andreas Schwab
2015-10-27 10:21 ` Juanma Barranquero
2015-10-27 16:03 ` Juanma Barranquero
2015-10-27 16:03 ` Juanma Barranquero
2015-10-28 1:51 ` Stephen Leake
2015-10-28 1:51 ` Stephen Leake
2015-10-28 9:08 ` Juanma Barranquero
2015-10-28 17:38 ` Juanma Barranquero
2015-10-28 9:08 ` Juanma Barranquero
2015-10-28 19:19 ` Stefan Monnier
2015-10-29 6:30 ` Andreas Röhler
2015-10-29 9:41 ` Juanma Barranquero
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