GNU bug report logs - #72296
29.4; cperl-mode parsing error

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: brian <me <at> briang.org>
To: bug-gnu-emacs <at> gnu.org
Subject: 29.4; cperl-mode parsing error
Date: Thu, 25 Jul 2024 14:29:37 +0100

I started emacs using 'emacs -Q /tmp/some-empty-file.pl' and activated
cperl mode by 'M-x cperl-mode'. I typed 'for (2..$n/2) {}' into the
empty buffer and as soon as I pressed '/' there was an error message in
the minibuffer

End of ‘/ ... /’ string/RE not found: (scan-error Unbalanced parentheses 
11 38)

and syntax hilighting was broken. Inserting a single space before '$'
cleared the error and fixed the hilighting.



In GNU Emacs 29.4 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.38,
cairo version 1.18.0) of 2024-06-24 built on dev
Windowing system distributor 'The X.Org Foundation', version 11.0.12302000
System Description: Ubuntu 23.10

Configured using:
'configure --prefix=/opt/emacs --with-cairo --with-libsystemd
--with-mailutils --with-native-compilation --with-pop=yes
--with-sound=alsa --with-toolkit-scroll-bars --with-x-toolkit=gtk3
--with-x=yes --without-gconf 'CFLAGS=-g -O2''

Configured features:
CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON
LIBSELINUX LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG
SECCOMP SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER WEBP
X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB

Important settings:
value of $LANG: en_GB.UTF-8
value of $XMODIFIERS: @im=ibus
locale-coding-system: utf-8-unix

Major mode: CPerl

Minor modes in effect:
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column-number-mode: t
line-number-mode: t
transient-mark-mode: t
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t

Load-path shadows:
/home/brian/.emacs.d/elpa/transient-20240603.2200/transient hides 
/opt/emacs/share/emacs/29.4/lisp/transient

Features:
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Memory information:
((conses 16 507989 330210)
(symbols 48 28255 420)
(strings 32 141117 47270)
(string-bytes 1 4103290)
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(vector-slots 8 844183 452452)
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Message #8 received at 72296 <at> debbugs.gnu.org (full text, mbox):

From: Andrea Corallo <acorallo <at> gnu.org>
To: brian <me <at> briang.org>
Cc: 72296 <at> debbugs.gnu.org
Subject: Re: bug#72296: 29.4; cperl-mode parsing error
Date: Thu, 25 Jul 2024 13:01:30 -0400

brian <me <at> briang.org> writes:

> I started emacs using 'emacs -Q /tmp/some-empty-file.pl' and activated
> cperl mode by 'M-x cperl-mode'. I typed 'for (2..$n/2) {}' into the
> empty buffer and as soon as I pressed '/' there was an error message in
> the minibuffer
>
> End of ‘/ ... /’ string/RE not found: (scan-error Unbalanced
> parentheses 11 38)
>
> and syntax hilighting was broken. Inserting a single space before '$'
> cleared the error and fixed the hilighting.
>
>
>
> In GNU Emacs 29.4 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.38,
> cairo version 1.18.0) of 2024-06-24 built on dev
> Windowing system distributor 'The X.Org Foundation', version 11.0.12302000
> System Description: Ubuntu 23.10

I might be doing something wrong but I cannot reproduce on emacs-30,
could you confirm?  29 is not under development anymore.

  Andrea

Message #11 received at 72296 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Andrea Corallo <acorallo <at> gnu.org>
Cc: me <at> briang.org, 72296 <at> debbugs.gnu.org
Subject: Re: bug#72296: 29.4; cperl-mode parsing error
Date: Thu, 25 Jul 2024 22:06:03 +0300

> Cc: 72296 <at> debbugs.gnu.org
> From: Andrea Corallo <acorallo <at> gnu.org>
> Date: Thu, 25 Jul 2024 13:01:30 -0400
> 
> brian <me <at> briang.org> writes:
> 
> > I started emacs using 'emacs -Q /tmp/some-empty-file.pl' and activated
> > cperl mode by 'M-x cperl-mode'. I typed 'for (2..$n/2) {}' into the
> > empty buffer and as soon as I pressed '/' there was an error message in
> > the minibuffer
> >
> > End of ‘/ ... /’ string/RE not found: (scan-error Unbalanced
> > parentheses 11 38)
> >
> > and syntax hilighting was broken. Inserting a single space before '$'
> > cleared the error and fixed the hilighting.
> >
> >
> >
> > In GNU Emacs 29.4 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.38,
> > cairo version 1.18.0) of 2024-06-24 built on dev
> > Windowing system distributor 'The X.Org Foundation', version 11.0.12302000
> > System Description: Ubuntu 23.10
> 
> I might be doing something wrong but I cannot reproduce on emacs-30,
> could you confirm?  29 is not under development anymore.

I can reproduce on master.  Be sure to invoke cperl-mode, and type
exactly the text the OP shows.

Message #14 received at 72296 <at> debbugs.gnu.org (full text, mbox):

From: Harald Jörg <haj <at> posteo.de>
To: 72296 <at> debbugs.gnu.org
Cc: brian <me <at> briang.org>
Subject: Re: bug#72296: 29.4; cperl-mode parsing error
Date: Thu, 25 Jul 2024 19:06:35 +0000

tags 72296 confirmed
severity 72296 normal
owner 72296 Harald Jörg <haj <at> posteo.de>
thanks

brian <me <at> briang.org> writes:

> I started emacs using 'emacs -Q /tmp/some-empty-file.pl' and activated
> cperl mode by 'M-x cperl-mode'. I typed 'for (2..$n/2) {}' into the
> empty buffer and as soon as I pressed '/' there was an error message in
> the minibuffer
>
> End of ‘/ ... /’ string/RE not found: (scan-error Unbalanced
> parentheses 11 38)
>
> and syntax hilighting was broken. Inserting a single space before '$'
> cleared the error and fixed the hilighting.

I can reproduce this and am about to prepare a fix.

That code sits here since 1997, I find it rather surprising that it has
not surfaced until now.  I'll run some tests and add a test case.  If I
am not mistaken, then replacing a `progn` with `save-excursion` should
do the trick:

index b85db699e72..34481925d3e 100644
--- a/lisp/progmodes/cperl-mode.el
+++ b/lisp/progmodes/cperl-mode.el
@@ -4108,7 +4108,7 @@ cperl-find-pods-heres
                                    (and (eq (preceding-char) ?\})
                                         (cperl-after-block-p (point-min)))
                                    (and (eq (char-syntax (preceding-char)) ?w)
-                                        (progn
+                                        (save-excursion
                                           (forward-sexp -1)
 ;; After these keywords `/' starts a RE.  One should add all the
 ;; functions/builtins which expect an argument, but ...

In newer versions the line numbers are different (~4650) but the issue
is the same.  The unprotected (forward-sexp -1) skips over $n and the
two characters before that are '..' which, in the following clause,
makes the construct look like a flip-flop operator where '/' does start
a regular expression.  Using 'save-excursion' undoes the skip before
running the next checks.

-- 
Cheers,
haj

Message #21 received at 72296 <at> debbugs.gnu.org (full text, mbox):

From: Andrea Corallo <acorallo <at> gnu.org>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: me <at> briang.org, 72296 <at> debbugs.gnu.org
Subject: Re: bug#72296: 29.4; cperl-mode parsing error
Date: Fri, 26 Jul 2024 03:59:56 -0400

Eli Zaretskii <eliz <at> gnu.org> writes:

>> Cc: 72296 <at> debbugs.gnu.org
>> From: Andrea Corallo <acorallo <at> gnu.org>
>> Date: Thu, 25 Jul 2024 13:01:30 -0400
>> 
>> brian <me <at> briang.org> writes:
>> 
>> > I started emacs using 'emacs -Q /tmp/some-empty-file.pl' and activated
>> > cperl mode by 'M-x cperl-mode'. I typed 'for (2..$n/2) {}' into the
>> > empty buffer and as soon as I pressed '/' there was an error message in
>> > the minibuffer
>> >
>> > End of ‘/ ... /’ string/RE not found: (scan-error Unbalanced
>> > parentheses 11 38)
>> >
>> > and syntax hilighting was broken. Inserting a single space before '$'
>> > cleared the error and fixed the hilighting.
>> >
>> >
>> >
>> > In GNU Emacs 29.4 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.38,
>> > cairo version 1.18.0) of 2024-06-24 built on dev
>> > Windowing system distributor 'The X.Org Foundation', version 11.0.12302000
>> > System Description: Ubuntu 23.10
>> 
>> I might be doing something wrong but I cannot reproduce on emacs-30,
>> could you confirm?  29 is not under development anymore.
>
> I can reproduce on master.  Be sure to invoke cperl-mode, and type
> exactly the text the OP shows.

So I do but can't reproduce, I must be doing something wrong sorry 🤷

Message #24 received at 72296 <at> debbugs.gnu.org (full text, mbox):

From: Andrea Corallo <acorallo <at> gnu.org>
To: brian greenfield <dev <at> briang.org>
Cc: 72296 <at> debbugs.gnu.org
Subject: Re: bug#72296: 29.4; cperl-mode parsing error
Date: Fri, 26 Jul 2024 04:03:35 -0400

brian greenfield <dev <at> briang.org> writes:

> On Thu, Jul 25, 2024 at 01:01:30PM -0400, Andrea Corallo wrote:
>> I might be doing something wrong but I cannot reproduce on emacs-30,
>> could you confirm?  29 is not under development anymore.
>
> No, it was me in the wrong. My emacs-30 was too old, retrying on a newer
> emacs-30 has the bug fixed.
>
> Sorry for the noise.

[re-adding the list, please keep it Cced in the replies]

Actually the others can still reproduce on more recent versions (I
can't), so I'm all but sure this is solved (and I'm a little puzzled on
the reproducibility of this).

  Andrea

Message #27 received at 72296 <at> debbugs.gnu.org (full text, mbox):

From: Harald Jörg <haj <at> posteo.de>
To: Andrea Corallo <acorallo <at> gnu.org>
Cc: brian greenfield <dev <at> briang.org>, 72296 <at> debbugs.gnu.org
Subject: Re: bug#72296: 29.4; cperl-mode parsing error
Date: Fri, 26 Jul 2024 10:20:12 +0000

Andrea Corallo <acorallo <at> gnu.org> writes:

> brian greenfield <dev <at> briang.org> writes:
>
>> On Thu, Jul 25, 2024 at 01:01:30PM -0400, Andrea Corallo wrote:
>>> I might be doing something wrong but I cannot reproduce on emacs-30,
>>> could you confirm?  29 is not under development anymore.
>>
>> No, it was me in the wrong. My emacs-30 was too old, retrying on a newer
>> emacs-30 has the bug fixed.
>>
>> Sorry for the noise.
>
> [re-adding the list, please keep it Cced in the replies]
>
> Actually the others can still reproduce on more recent versions (I
> can't), so I'm all but sure this is solved (and I'm a little puzzled on
> the reproducibility of this).

If either of you built your emacs-30 with the commit c27055a9 in place,
then it is supposed to be not reproducible: I fixed it yesterday.

Until the regular rebasing happens, it can still be reproduced on
master.  I may be stating the obvious, but the code is

for (2..$n/2) {}

without any enclosing quotes.  If you apply cperl-mode for this snippet,
you should see the message "End of ‘/ ... /’ string/RE not found:
(scan-error Unbalanced parentheses 11 17)" in the echo area, the slash
should be formatted with font-lock-constant-face, the 2 following it
with font-lock-string-face and the closing paren with
font-lock-warning-face.

If you can not reproduce the error on master, then I'd like to examine
this further before closing the bug.

-- 
Cheers,
haj

Message #30 received at 72296 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Andrea Corallo <acorallo <at> gnu.org>
Cc: dev <at> briang.org, 72296 <at> debbugs.gnu.org
Subject: Re: bug#72296: 29.4; cperl-mode parsing error
Date: Fri, 26 Jul 2024 13:38:32 +0300

> Cc: 72296 <at> debbugs.gnu.org
> From: Andrea Corallo <acorallo <at> gnu.org>
> Date: Fri, 26 Jul 2024 04:03:35 -0400
> 
> brian greenfield <dev <at> briang.org> writes:
> 
> > On Thu, Jul 25, 2024 at 01:01:30PM -0400, Andrea Corallo wrote:
> >> I might be doing something wrong but I cannot reproduce on emacs-30,
> >> could you confirm?  29 is not under development anymore.
> >
> > No, it was me in the wrong. My emacs-30 was too old, retrying on a newer
> > emacs-30 has the bug fixed.
> >
> > Sorry for the noise.
> 
> [re-adding the list, please keep it Cced in the replies]
> 
> Actually the others can still reproduce on more recent versions (I
> can't), so I'm all but sure this is solved (and I'm a little puzzled on
> the reproducibility of this).

Wasn't this fixed today on the emacs-30 branch?

Message #33 received at 72296 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: brian greenfield <dev <at> briang.org>
Cc: acorallo <at> gnu.org, 72296 <at> debbugs.gnu.org, haj <at> posteo.de
Subject: Re: bug#72296: Acknowledgement (29.4; cperl-mode parsing error)
Date: Fri, 26 Jul 2024 16:56:30 +0300

> Date: Fri, 26 Jul 2024 14:21:28 +0100
> From: brian greenfield <dev <at> briang.org>
> Cc: Harald Jörg <haj <at> posteo.de>,
> 	Andrea Corallo <acorallo <at> gnu.org>, Eli Zaretskii <eliz <at> gnu.org>
> 
> I compiled emacs-30 (87389f9ff90) and master (52cae67e1e7) in the last couple of
> hours, and tested with 'for (2..$n/2) {}'.
> 
> emacs-30 is fixed: the spurious error has gone, and hilighting is working as
> expected. master is still broken.

The fix was installed on the emacs-30 branch, it will be merged to
master soon.

Message #36 received at 72296 <at> debbugs.gnu.org (full text, mbox):

From: brian greenfield <dev <at> briang.org>
To: 72296 <at> debbugs.gnu.org
Cc: Eli Zaretskii <eliz <at> gnu.org>, Andrea Corallo <acorallo <at> gnu.org>,
 Harald Jörg <haj <at> posteo.de>
Subject: Re: bug#72296: Acknowledgement (29.4; cperl-mode parsing error)
Date: Fri, 26 Jul 2024 14:21:28 +0100

I compiled emacs-30 (87389f9ff90) and master (52cae67e1e7) in the last couple of
hours, and tested with 'for (2..$n/2) {}'.

emacs-30 is fixed: the spurious error has gone, and hilighting is working as
expected. master is still broken.

Message #41 received at 72296-done <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Harald Jörg <haj <at> posteo.de>
Cc: me <at> briang.org, 72296-done <at> debbugs.gnu.org
Subject: Re: bug#72296: 29.4; cperl-mode parsing error
Date: Sat, 27 Jul 2024 11:04:15 +0300

> Cc: brian <me <at> briang.org>
> From: Harald Jörg <haj <at> posteo.de>
> Date: Thu, 25 Jul 2024 19:06:35 +0000
> 
> brian <me <at> briang.org> writes:
> 
> > I started emacs using 'emacs -Q /tmp/some-empty-file.pl' and activated
> > cperl mode by 'M-x cperl-mode'. I typed 'for (2..$n/2) {}' into the
> > empty buffer and as soon as I pressed '/' there was an error message in
> > the minibuffer
> >
> > End of ‘/ ... /’ string/RE not found: (scan-error Unbalanced
> > parentheses 11 38)
> >
> > and syntax hilighting was broken. Inserting a single space before '$'
> > cleared the error and fixed the hilighting.
> 
> I can reproduce this and am about to prepare a fix.
> 
> That code sits here since 1997, I find it rather surprising that it has
> not surfaced until now.  I'll run some tests and add a test case.  If I
> am not mistaken, then replacing a `progn` with `save-excursion` should
> do the trick:
> 
> index b85db699e72..34481925d3e 100644
> --- a/lisp/progmodes/cperl-mode.el
> +++ b/lisp/progmodes/cperl-mode.el
> @@ -4108,7 +4108,7 @@ cperl-find-pods-heres
>                                     (and (eq (preceding-char) ?\})
>                                          (cperl-after-block-p (point-min)))
>                                     (and (eq (char-syntax (preceding-char)) ?w)
> -                                        (progn
> +                                        (save-excursion
>                                            (forward-sexp -1)
>  ;; After these keywords `/' starts a RE.  One should add all the
>  ;; functions/builtins which expect an argument, but ...
> 
> In newer versions the line numbers are different (~4650) but the issue
> is the same.  The unprotected (forward-sexp -1) skips over $n and the
> two characters before that are '..' which, in the following clause,
> makes the construct look like a flip-flop operator where '/' does start
> a regular expression.  Using 'save-excursion' undoes the skip before
> running the next checks.

Thanks, since this appears to be fixed on the emacs-30 branch, I'm
closing this bug.

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