GNU bug report logs - #79269
30.1; cperl-mode does not handle signatures correctly

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

From: John Ciolfi <john.ciolfi.32 <at> gmail.com>
To: <bug-gnu-emacs <at> gnu.org>
Subject: 30.1; cperl-mode does not handle signatures correctly
Date: Tue, 19 Aug 2025 12:05:37 -0400

1. In a temporary directory, say ~/tmp/, get latest cperl-mode.el from
   https://github.com/emacs-mirror/emacs/blob/master/lisp/progmodes/cperl-mode.el
   I used the Jul-28-2025 version
   https://github.com/emacs-mirror/emacs/blob/cef4302d309e26c2191821ba998518fb89fff54e/lisp/progmodes/cperl-mode.el

2. cd ~/tmp

3. emacs -Q -L .           # Using emacs 30.1

4. M-x byte-compile-file RET cperl-mode.el RET

5. C-x C-f foo.pl

   C-x h   # select all of foo.pl
   C-M-\   # indent foo.pl

Here's the indented foo.pl. Notice that there are a couple problems
which appears to be due to the incorrect handling of perl signatures.
Note, perl-mode.el seems to handle signatures correctly, so maybe that
code can be borrowed for cperl-mode.el?


# -*- mode: cperl -*-
use strict;
use warnings;
use experimental 'signatures';

foo(1);

sub foo (
	 $in1,
	 $optionsHPtr = {},
	 $otherOption1 = 1,	# Bug: wrong face for this option
	) {
 
   my $a = 1;  # Bug: should be indented by 2 spaces

 # Bug: following are not indented due to use of signatures
 my $b = 2;
 return $a + $b + $in1;
}
   


In GNU Emacs 30.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.38,
 cairo version 1.16.0) of 2025-04-04, modified by Debian built on sbuild
Windowing system distributor 'The X.Org Foundation', version 11.0.12101006
System Description: Debian GNU/Linux 12 (bookworm)

Configured using:
 'configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/libexec
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-libsystemd --with-pop=yes
 --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/30.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/30.1/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-mailutils --build
 x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib
 --libexecdir=/usr/libexec --localstatedir=/var/lib
 --infodir=/usr/share/info --mandir=/usr/share/man --with-libsystemd
 --with-pop=yes
 --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/30.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/30.1/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-mailutils --with-cairo
 --with-x=yes --with-x-toolkit=gtk3 --with-toolkit-scroll-bars
 'CFLAGS=-g -O2
 -ffile-prefix-map=/build/reproducible-path/emacs-30.1+1=. -fstack-protector-strong
 -Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
 -D_FORTIFY_SOURCE=2' LDFLAGS=-Wl,-z,relro'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NATIVE_COMP
NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS TREE_SITTER WEBP X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: CPerl

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  minibuffer-regexp-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
/home/ciolfi/tmp/cperl-mode hides /usr/share/emacs/30.1/lisp/progmodes/cperl-mode

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny dired
dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg rfc6068
epg-config gnus-util time-date mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader cl-loaddefs cl-lib sendmail
rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils compile
text-property-search comint subr-x ansi-osc ansi-color ring comp-run
bytecomp byte-compile comp-common cperl-mode rx facemenu rmc iso-transl
tooltip cconv eldoc paren electric uniquify ediff-hook vc-hooks
lisp-float-type elisp-mode mwheel term/x-win x-win term/common-win x-dnd
touch-screen tool-bar dnd fontset image regexp-opt fringe tabulated-list
replace newcomment text-mode lisp-mode prog-mode register page tab-bar
menu-bar rfn-eshadow isearch easymenu timer select scroll-bar mouse
jit-lock font-lock syntax font-core term/tty-colors frame minibuffer
nadvice seq simple cl-generic indonesian philippine cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european
ethiopic indian cyrillic chinese composite emoji-zwj charscript charprop
case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
cl-preloaded button loaddefs theme-loaddefs faces cus-face macroexp
files window text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget keymap hashtable-print-readable backquote
threads dbusbind inotify lcms2 dynamic-setting system-font-setting
font-render-setting cairo gtk x-toolkit xinput2 x multi-tty move-toolbar
make-network-process native-compile emacs)

Memory information:
((conses 16 84401 12096) (symbols 48 7366 0) (strings 32 20464 1856)
 (string-bytes 1 700197) (vectors 16 11848)
 (vector-slots 8 163636 10525) (floats 8 26 34) (intervals 56 418 0)
 (buffers 992 12))

Message #8 received at 79269 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: John Ciolfi <john.ciolfi.32 <at> gmail.com>, Harald Jörg
 <haj <at> posteo.de>
Cc: 79269 <at> debbugs.gnu.org
Subject: Re: bug#79269: 30.1; cperl-mode does not handle signatures correctly
Date: Tue, 19 Aug 2025 19:36:21 +0300

> From: John Ciolfi <john.ciolfi.32 <at> gmail.com>
> Date: Tue, 19 Aug 2025 12:05:37 -0400
> 
> 
> 1. In a temporary directory, say ~/tmp/, get latest cperl-mode.el from
>    https://github.com/emacs-mirror/emacs/blob/master/lisp/progmodes/cperl-mode.el
>    I used the Jul-28-2025 version
>    https://github.com/emacs-mirror/emacs/blob/cef4302d309e26c2191821ba998518fb89fff54e/lisp/progmodes/cperl-mode.el
> 
> 2. cd ~/tmp
> 
> 3. emacs -Q -L .           # Using emacs 30.1
> 
> 4. M-x byte-compile-file RET cperl-mode.el RET
> 
> 5. C-x C-f foo.pl
> 
>    C-x h   # select all of foo.pl
>    C-M-\   # indent foo.pl
> 
> Here's the indented foo.pl. Notice that there are a couple problems
> which appears to be due to the incorrect handling of perl signatures.
> Note, perl-mode.el seems to handle signatures correctly, so maybe that
> code can be borrowed for cperl-mode.el?
> 
> 
> # -*- mode: cperl -*-
> use strict;
> use warnings;
> use experimental 'signatures';
> 
> foo(1);
> 
> sub foo (
> 	 $in1,
> 	 $optionsHPtr = {},
> 	 $otherOption1 = 1,	# Bug: wrong face for this option
> 	) {
>  
>    my $a = 1;  # Bug: should be indented by 2 spaces
> 
>  # Bug: following are not indented due to use of signatures
>  my $b = 2;
>  return $a + $b + $in1;
> }

Thanks.

Harald, any comments or suggestions?

Message #11 received at 79269 <at> debbugs.gnu.org (full text, mbox):

From: Harald Jörg <haj <at> posteo.de>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 79269 <at> debbugs.gnu.org, John Ciolfi <john.ciolfi.32 <at> gmail.com>
Subject: Re: bug#79269: 30.1; cperl-mode does not handle signatures correctly
Date: Wed, 20 Aug 2025 13:45:17 +0000

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

>> From: John Ciolfi <john.ciolfi.32 <at> gmail.com>
>> Date: Tue, 19 Aug 2025 12:05:37 -0400
>> 
>> 
>> 1. In a temporary directory, say ~/tmp/, get latest cperl-mode.el from
>>    https://github.com/emacs-mirror/emacs/blob/master/lisp/progmodes/cperl-mode.el
>>    I used the Jul-28-2025 version
>>    https://github.com/emacs-mirror/emacs/blob/cef4302d309e26c2191821ba998518fb89fff54e/lisp/progmodes/cperl-mode.el
>> 
>> 2. cd ~/tmp
>> 
>> 3. emacs -Q -L .           # Using emacs 30.1
>> 
>> 4. M-x byte-compile-file RET cperl-mode.el RET
>> 
>> 5. C-x C-f foo.pl
>> 
>>    C-x h   # select all of foo.pl
>>    C-M-\   # indent foo.pl
>> 
>> Here's the indented foo.pl. Notice that there are a couple problems
>> which appears to be due to the incorrect handling of perl signatures.
>> Note, perl-mode.el seems to handle signatures correctly, so maybe that
>> code can be borrowed for cperl-mode.el?
>> 
>> 
>> # -*- mode: cperl -*-
>> use strict;
>> use warnings;
>> use experimental 'signatures';
>> 
>> foo(1);
>> 
>> sub foo (
>> 	 $in1,
>> 	 $optionsHPtr = {},
>> 	 $otherOption1 = 1,	# Bug: wrong face for this option
>> 	) {
>>  
>>    my $a = 1;  # Bug: should be indented by 2 spaces
>> 
>>  # Bug: following are not indented due to use of signatures
>>  my $b = 2;
>>  return $a + $b + $in1;
>> }
>
> Thanks.
>
> Harald, any comments or suggestions?

Yes :)

I am glad to see some different code layouts than I use myself,
especially when they expose bugs.  I did expect this to happen with
signatures, and even more with classes.  There isn't much code in the
wild using these features.

I am afraid that borrowing from perl-mode.el is no viable solution.
perl-mode treats signatures correctly ... by not recognizing them at
all.

As for the indentation, I am optimistic that this can be fixed by
fiddling with some regular expressions.  In a slightly different coding
style where the opening brace of the subroutine is on a new line,
indentation works as it should:

# ----------------------------------------------------------
use experimental 'signatures';

foo(1);

sub foo (
	 $in1,
	 $optionsHPtr = {},
	 $otherOption1 = 1,	# Bug: wrong face for this option
	)
{
   my $a = 1;  # Bug: should be indented by 2 spaces

 # Bug: following are not indented due to use of signatures
 my $b = 2;
 return $a + $b + $in1;
}
# ----------------------------------------------------------

So I'll try to prepare a patch and add one or more test cases.


As for the wrong face: This is a bug where cperl-mode trips over its
ambitions.  Per default, cperl-mode highlights scalar variables when
they are declared, but not when they are used.  A signature is (sort of)
a declaration, so variables ought to have variable-face applied.  The
challenge comes when declarations come with initializers.  For example:

  sub foo ($editor = $emacs) {
     ...
  }

Here, "$editor" is a declaration whereas "$emacs" is use of a variable
declared elsewhere.  Initializers are (almost) arbitrary Perl
expressions, so we need to compromise how, and how far we are looking
for more declarations in the same signature.  The current implementation
is rather rigid and takes the first "{" as the beginning of the
subroutine body and therefore fails to find declarations after the
initializer "{}".  I am optimistic that I can come up with a more
flexible solution.  There will always be limitations, but the empty hash
reference "{}" is a reasonable case to treat correctly.


BTW: perl-mode does not distinguish between declaration and use and
always applies variable-face.  In cperl-mode this behaviour can be
customized by setting cperl-highlight-variables-indiscriminately to
non-nil.

-- 
Cheers,
haj

Message #16 received at 79269-done <at> debbugs.gnu.org (full text, mbox):

From: Harald Jörg <haj <at> posteo.de>
To: 79269-done <at> debbugs.gnu.org
Subject: Indentation and fontification of signatures fixed
Date: Fri, 22 Aug 2025 12:11:44 +0000

Both parts of the bug report (thanks for the excellent recipe) have now
been fixed in the "master" branch, tests have been added using the
example code from the report.
-- 
Cheers,
haj

Message #19 received at 79269 <at> debbugs.gnu.org (full text, mbox):

From: John C <john.ciolfi.32 <at> gmail.com>
To: 79269 <at> debbugs.gnu.org
Subject: Re: bug#79269: closed (Indentation and fontification of signatures
 fixed)
Date: Wed, 27 Aug 2025 20:12:48 -0400

[Message part 1 (text/plain, inline)]

Hi

Thanks for trying to fix this, but it seems there's still an issue. In the
attached test.pl, the indent is off. Can you take a look?



On Fri, Aug 22, 2025 at 8:12 AM GNU bug Tracking System <
help-debbugs <at> gnu.org> wrote:

> Your bug report
>
> #79269: 30.1; cperl-mode does not handle signatures correctly
>
> which was filed against the emacs package, has been closed.
>
> The explanation is attached below, along with your original report.
> If you require more details, please reply to 79269 <at> debbugs.gnu.org.
>
> --
> 79269: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=79269
> GNU Bug Tracking System
> Contact help-debbugs <at> gnu.org with problems
>
>
>
> ---------- Forwarded message ----------
> From: "Harald Jörg" <haj <at> posteo.de>
> To: 79269-done <at> debbugs.gnu.org
> Cc:
> Bcc:
> Date: Fri, 22 Aug 2025 12:11:44 +0000
> Subject: Indentation and fontification of signatures fixed
> Both parts of the bug report (thanks for the excellent recipe) have now
> been fixed in the "master" branch, tests have been added using the
> example code from the report.
> --
> Cheers,
> haj
>
>
>
>
> ---------- Forwarded message ----------
> From: John Ciolfi <john.ciolfi.32 <at> gmail.com>
> To: <bug-gnu-emacs <at> gnu.org>
> Cc:
> Bcc:
> Date: Tue, 19 Aug 2025 12:05:37 -0400
> Subject: 30.1; cperl-mode does not handle signatures correctly
>
> 1. In a temporary directory, say ~/tmp/, get latest cperl-mode.el from
>
> https://github.com/emacs-mirror/emacs/blob/master/lisp/progmodes/cperl-mode.el
>    I used the Jul-28-2025 version
>
> https://github.com/emacs-mirror/emacs/blob/cef4302d309e26c2191821ba998518fb89fff54e/lisp/progmodes/cperl-mode.el
>
> 2. cd ~/tmp
>
> 3. emacs -Q -L .           # Using emacs 30.1
>
> 4. M-x byte-compile-file RET cperl-mode.el RET
>
> 5. C-x C-f foo.pl
>
>    C-x h   # select all of foo.pl
>    C-M-\   # indent foo.pl
>
> Here's the indented foo.pl. Notice that there are a couple problems
> which appears to be due to the incorrect handling of perl signatures.
> Note, perl-mode.el seems to handle signatures correctly, so maybe that
> code can be borrowed for cperl-mode.el?
>
>
> # -*- mode: cperl -*-
> use strict;
> use warnings;
> use experimental 'signatures';
>
> foo(1);
>
> sub foo (
>          $in1,
>          $optionsHPtr = {},
>          $otherOption1 = 1,     # Bug: wrong face for this option
>         ) {
>
>    my $a = 1;  # Bug: should be indented by 2 spaces
>
>  # Bug: following are not indented due to use of signatures
>  my $b = 2;
>  return $a + $b + $in1;
> }
>
>
>
> In GNU Emacs 30.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.38,
>  cairo version 1.16.0) of 2025-04-04, modified by Debian built on sbuild
> Windowing system distributor 'The X.Org Foundation', version 11.0.12101006
> System Description: Debian GNU/Linux 12 (bookworm)
>
> Configured using:
>  'configure --build x86_64-linux-gnu --prefix=/usr
>  --sharedstatedir=/var/lib --libexecdir=/usr/libexec
>  --localstatedir=/var/lib --infodir=/usr/share/info
>  --mandir=/usr/share/man --with-libsystemd --with-pop=yes
>
>  --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/30.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/30.1/site-lisp:/usr/share/emacs/site-lisp
>  --with-sound=alsa --without-gconf --with-mailutils --build
>  x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib
>  --libexecdir=/usr/libexec --localstatedir=/var/lib
>  --infodir=/usr/share/info --mandir=/usr/share/man --with-libsystemd
>  --with-pop=yes
>
>  --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/30.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/30.1/site-lisp:/usr/share/emacs/site-lisp
>  --with-sound=alsa --without-gconf --with-mailutils --with-cairo
>  --with-x=yes --with-x-toolkit=gtk3 --with-toolkit-scroll-bars
>  'CFLAGS=-g -O2
>  -ffile-prefix-map=/build/reproducible-path/emacs-30.1+1=.
> -fstack-protector-strong
>  -Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
>  -D_FORTIFY_SOURCE=2' LDFLAGS=-Wl,-z,relro'
>
> Configured features:
> ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
> LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NATIVE_COMP
> NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF
> TOOLKIT_SCROLL_BARS TREE_SITTER WEBP X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB
>
> Important settings:
>   value of $LANG: en_US.UTF-8
>   locale-coding-system: utf-8-unix
>
> Major mode: CPerl
>
> Minor modes in effect:
>   tooltip-mode: t
>   global-eldoc-mode: t
>   show-paren-mode: t
>   electric-indent-mode: t
>   mouse-wheel-mode: t
>   tool-bar-mode: t
>   menu-bar-mode: t
>   file-name-shadow-mode: t
>   global-font-lock-mode: t
>   font-lock-mode: t
>   blink-cursor-mode: t
>   minibuffer-regexp-mode: t
>   line-number-mode: t
>   indent-tabs-mode: t
>   transient-mark-mode: t
>   auto-composition-mode: t
>   auto-encryption-mode: t
>   auto-compression-mode: t
>
> Load-path shadows:
> /home/ciolfi/tmp/cperl-mode hides
> /usr/share/emacs/30.1/lisp/progmodes/cperl-mode
>
> Features:
> (shadow sort mail-extr emacsbug message mailcap yank-media puny dired
> dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg rfc6068
> epg-config gnus-util time-date mm-decode mm-bodies mm-encode mail-parse
> rfc2231 mailabbrev gmm-utils mailheader cl-loaddefs cl-lib sendmail
> rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils compile
> text-property-search comint subr-x ansi-osc ansi-color ring comp-run
> bytecomp byte-compile comp-common cperl-mode rx facemenu rmc iso-transl
> tooltip cconv eldoc paren electric uniquify ediff-hook vc-hooks
> lisp-float-type elisp-mode mwheel term/x-win x-win term/common-win x-dnd
> touch-screen tool-bar dnd fontset image regexp-opt fringe tabulated-list
> replace newcomment text-mode lisp-mode prog-mode register page tab-bar
> menu-bar rfn-eshadow isearch easymenu timer select scroll-bar mouse
> jit-lock font-lock syntax font-core term/tty-colors frame minibuffer
> nadvice seq simple cl-generic indonesian philippine cham georgian
> utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
> japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european
> ethiopic indian cyrillic chinese composite emoji-zwj charscript charprop
> case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
> cl-preloaded button loaddefs theme-loaddefs faces cus-face macroexp
> files window text-properties overlay sha1 md5 base64 format env
> code-pages mule custom widget keymap hashtable-print-readable backquote
> threads dbusbind inotify lcms2 dynamic-setting system-font-setting
> font-render-setting cairo gtk x-toolkit xinput2 x multi-tty move-toolbar
> make-network-process native-compile emacs)
>
> Memory information:
> ((conses 16 84401 12096) (symbols 48 7366 0) (strings 32 20464 1856)
>  (string-bytes 1 700197) (vectors 16 11848)
>  (vector-slots 8 163636 10525) (floats 8 26 34) (intervals 56 418 0)
>  (buffers 992 12))
>
>
>

[Message part 2 (text/html, inline)]

[test.pl (application/x-perl, attachment)]

Message #22 received at 79269 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: John C <john.ciolfi.32 <at> gmail.com>, Harald Jörg
 <haj <at> posteo.de>
Cc: 79269 <at> debbugs.gnu.org
Subject: Re: bug#79269: Indentation and fontification of signatures fixed
Date: Thu, 28 Aug 2025 08:54:07 +0300

> From: John C <john.ciolfi.32 <at> gmail.com>
> Date: Wed, 27 Aug 2025 20:12:48 -0400
> 
> Thanks for trying to fix this, but it seems there's still an issue. In the attached test.pl, the indent is off. Can
> you take a look?

Please always CC the author of the fix on the followup messages.  Many
people do not subscribe to the bug list, so they don't see your
responses otherwise.

Harald, could you please look into this?

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