bug#33114: 25.2; Emacs hangs on closing a perenthesis in a regexp in cperl mode

bug#33114: 25.2; Emacs hangs on closing a perenthesis in a regexp in cperl mode

[Vincent Lefevre]

Consider the following file:

# -*- mode: cperl -*-
s/./(/e;

1. Open it with "emacs -Q".
2. Put the cursor just after the opening parenthesis.
3. Type ')' (closing parenthesis).

This makes Emacs hang. A C-g alone has no effect. Several C-g in a row
may give the control back to the user.

Tested under Debian/unstable.



In GNU Emacs 25.2.2 (x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
 of 2018-07-11, modified by Debian built on x86-ubc-01
Windowing system distributor 'The X.Org Foundation', version 11.0.12001000
System Description:	Debian GNU/Linux stable-updates (sid)

Configured using:
 'configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
 --enable-locallisppath=/etc/emacs25:/etc/emacs:/usr/local/share/emacs/25.2/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/25.2/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --build x86_64-linux-gnu
 --prefix=/usr --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
 --enable-locallisppath=/etc/emacs25:/etc/emacs:/usr/local/share/emacs/25.2/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/25.2/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-x=yes --with-x-toolkit=gtk3
 --with-toolkit-scroll-bars 'CFLAGS=-g -O2
 -fdebug-prefix-map=/build/emacs25-cfFROJ/emacs25-25.2+1=.
 -fstack-protector-strong -Wformat -Werror=format-security -Wall'
 'CPPFLAGS=-Wdate-time -D_FORTIFY_SOURCE=2' LDFLAGS=-Wl,-z,relro'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11

Important settings:
  value of $LC_COLLATE: POSIX
  value of $LC_CTYPE: en_US.UTF-8
  value of $LC_TIME: en_DK
  value of $LANG: POSIX
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  display-time-mode: t
  show-paren-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
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  global-font-lock-mode: t
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  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
Loading cjk-enc...done
Loading /etc/emacs/site-start.d/50latex-cjk-common.el (source)...done
Loading /etc/emacs/site-start.d/50latex-cjk-thai.el (source)...done
Loading /etc/emacs/site-start.d/50psvn.el (source)...done
Loading /etc/emacs/site-start.d/50python-docutils.el (source)...done
Loading /etc/emacs/site-start.d/50texlive-lang-english.el (source)...done
Loading /etc/emacs/site-start.d/50why3.el (source)...done
Loading /home/vinc17/share/emacs/site-lisp/mutteditor.el (source)...done
Loading time...done
For information about GNU Emacs and the GNU system, type C-h C-a.

Load-path shadows:
/usr/share/emacs/25.2/site-lisp/why3 hides /usr/share/emacs/site-lisp/why3
/usr/share/emacs/25.2/site-lisp/debian-startup hides /usr/share/emacs/site-lisp/debian-startup
/usr/share/emacs25/site-lisp/cmake-data/cmake-mode hides /usr/share/emacs/site-lisp/cmake-mode
/usr/share/emacs/site-lisp/rst hides /usr/share/emacs/25.2/lisp/textmodes/rst
/usr/share/emacs25/site-lisp/latex-cjk-thai/thai-word hides /usr/share/emacs/25.2/lisp/language/thai-word

Features:
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lisp-float-type mwheel x-win term/common-win x-dnd tool-bar dnd fontset
image regexp-opt fringe tabulated-list newcomment elisp-mode lisp-mode
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jka-cmpr-hook help simple abbrev minibuffer cl-preloaded nadvice
loaddefs button faces cus-face macroexp files text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote dbusbind inotify dynamic-setting
system-font-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty make-network-process emacs)

Memory information:
((conses 16 107238 7863)
 (symbols 48 22452 0)
 (miscs 40 54 113)
 (strings 32 20694 3424)
 (string-bytes 1 601857)
 (vectors 16 12880)
 (vector-slots 8 443130 2641)
 (floats 8 171 162)
 (intervals 56 266 0)
 (buffers 976 18))

bug#33114: 25.2; Emacs hangs on closing a perenthesis in a regexp in cperl mode

[Alan Mackenzie]

In article <mailman.2564.1540168987.1284.bug-gnu-emacs@gnu.org> you wrote:

> Consider the following file:

> # -*- mode: cperl -*-
> s/./(/e;

> 1. Open it with "emacs -Q".
> 2. Put the cursor just after the opening parenthesis.
> 3. Type ')' (closing parenthesis).

> This makes Emacs hang. A C-g alone has no effect. Several C-g in a row
> may give the control back to the user.

I tried this in Emacs 25.2 -Q under Gentoo.  I haven't yet been able to
reproduce the error.  Instead, on typing the ), I get the error message:

    End of `s/ ... // ... /' string/RE not found: (scan-error Unbalanced parentheses 29 32)

.  Maybe something in your Emacs build configuration is clashing with
something in cperl mode.

> Tested under Debian/unstable.

> In GNU Emacs 25.2.2 (x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
>  of 2018-07-11, modified by Debian built on x86-ubc-01
> Windowing system distributor 'The X.Org Foundation', version 11.0.12001000
> System Description:     Debian GNU/Linux stable-updates (sid)

-- 
Alan Mackenzie (Nuremberg, Germany).

bug#33114: 25.2; Emacs hangs on closing a perenthesis in a regexp in cperl mode

[Eli Zaretskii]

> From: Vincent Lefevre <vincent@vinc17.net>
> Date: Mon, 22 Oct 2018 02:37:49 +0200
> 
> 
> Consider the following file:
> 
> # -*- mode: cperl -*-
> s/./(/e;
> 
> 1. Open it with "emacs -Q".
> 2. Put the cursor just after the opening parenthesis.
> 3. Type ')' (closing parenthesis).
> 
> This makes Emacs hang. A C-g alone has no effect. Several C-g in a row
> may give the control back to the user.

Does the patch below produce good results?  (I don't use CPerl mode,
so I don't know if the highlighting after the change is correct.)

Thanks.

--- lisp/progmodes/cperl-mode.el~0	2018-06-11 06:32:21.000000000 +0300
+++ lisp/progmodes/cperl-mode.el	2018-10-23 18:02:06.924582600 +0300
@@ -8786,7 +8786,7 @@
 	(goto-char new-beg)))
     (setq beg (point))
     (goto-char end)
-    (while (and end
+    (while (and end (< end (point-max))
 		(progn
 		  (or (bolp) (condition-case nil
 				 (forward-line 1)

bug#33114: 25.2; Emacs hangs on closing a perenthesis in a regexp in cperl mode

[Vincent Lefevre]

On 2018-10-23 18:19:59 +0300, Eli Zaretskii wrote:
> > # -*- mode: cperl -*-
> > s/./(/e;
> > 
> > 1. Open it with "emacs -Q".
> > 2. Put the cursor just after the opening parenthesis.
> > 3. Type ')' (closing parenthesis).
> > 
> > This makes Emacs hang. A C-g alone has no effect. Several C-g in a row
> > may give the control back to the user.
> 
> Does the patch below produce good results?  (I don't use CPerl mode,
> so I don't know if the highlighting after the change is correct.)

Thanks, this solves the hang problem, and the highlighting still
seems to be correct.

Note that there is still a bug: I get an error

  End of ‘s/ ... // ... /’ string/RE not found: (scan-error Unbalanced parentheses 26 29)

but I already got this error without the patch under conditions
with which Emacs did not hang, e.g. with:

  s/./(/;

(i.e. without the 'e').

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)

bug#33114: 25.2; Emacs hangs on closing a perenthesis in a regexp in cperl mode

[Eli Zaretskii]

> Date: Thu, 25 Oct 2018 13:21:17 +0200
> From: Vincent Lefevre <vincent@vinc17.net>
> Cc: 33114@debbugs.gnu.org
> 
> > > 1. Open it with "emacs -Q".
> > > 2. Put the cursor just after the opening parenthesis.
> > > 3. Type ')' (closing parenthesis).
> > > 
> > > This makes Emacs hang. A C-g alone has no effect. Several C-g in a row
> > > may give the control back to the user.
> > 
> > Does the patch below produce good results?  (I don't use CPerl mode,
> > so I don't know if the highlighting after the change is correct.)
> 
> Thanks, this solves the hang problem, and the highlighting still
> seems to be correct.

Thanks, pushed to the emacs-26 branch.

> Note that there is still a bug: I get an error
> 
>   End of ‘s/ ... // ... /’ string/RE not found: (scan-error Unbalanced parentheses 26 29)
> 
> but I already got this error without the patch under conditions

Yes, I think this is a separate issue.