bug#11733: 24.1; cperl indentation bugs

bug#11733: 24.1; cperl indentation bugs

[Vincent Lefevre]

The indentation in CPerl mode is buggy on sub, even with the default
configuration (emacs -Q). Open the following file:

----------------------------------------
#!/usr/bin/env perl
# -*- mode: cperl -*-

sub foo
  {
  }

sub bar
  {
  }
----------------------------------------

and hit the [TAB] key over the "sub bar" line. This line is indented
by 2 columns instead of being left on the first column. More generally
this happens on all subs except the first one.

[TAB] on the '{' of sub bar (line 9 of the script) gives a 4-column
indentation instead of 2, but this may be a consequence of the above
problem.

Other indentation bugs:

----------------------------------------
#!/usr/bin/env perl
# -*- mode: cperl -*-

while (<>)
  {
    m:^  \d+ p:
      or die;
    m:^  \d+ :
      or die;
  }
----------------------------------------

[TAB] on "or die;" gives:
  * a 4-column indentation instead of 6 for the 1st one,
  * a 8-column indentation instead of 6 for the 2nd one.

Note: my old Debian bug report about these indentation bugs:

  http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=405684


In GNU Emacs 24.1.1 (x86_64-unknown-linux-gnu, GTK+ Version 2.24.10)
 of 2012-06-15 on ypig
Windowing system distributor `The X.Org Foundation', version 11.0.11201902
Configured using:
 `configure '--prefix=/usr/local/emacs-24.1' '--enable-asserts''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: POSIX
  value of $LC_CTYPE: en_US.UTF-8
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: en_DK
  value of $LANG: POSIX
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  display-time-mode: t
  show-paren-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<escape> x r e p o r t - b u <tab> <return>

Recent messages:
Loading /home/vlefevre/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:
None found.

Features:
(shadow sort gnus-util mail-extr warnings emacsbug message format-spec
rfc822 mml easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils time cus-start cus-load paren
cc-styles cc-align cc-engine cc-vars cc-defs regexp-opt time-date
tooltip ediff-hook vc-hooks lisp-float-type mwheel x-win x-dnd tool-bar
dnd fontset image fringe lisp-mode register page menu-bar rfn-eshadow
timer select scroll-bar mouse jit-lock font-lock syntax facemenu
font-core frame cham georgian utf-8-lang misc-lang vietnamese tibetan
thai tai-viet lao korean japanese hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese case-table epa-hook
jka-cmpr-hook help simple abbrev minibuffer loaddefs button faces
cus-face files text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget hashtable-print-readable backquote
make-network-process dbusbind dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty emacs)

bug#11733: 24.1; cperl indentation bugs

[Glenn Morris]

Vincent Lefevre wrote:

> The indentation in CPerl mode is buggy on sub,

Here at Emacs, we are discouraged from changing cperl-mode (not that I
want to myself); see eg bugs 10934, 8802.

But upstream [1] doesn't appear to have changed it in 4 years, so you're
kind of stuck AFAICS.

[1] http://math.berkeley.edu/~ilya/software/emacs/

bug#11733: 24.1; cperl indentation bugs

[Stefan Kangas]

Vincent Lefevre <vincent@vinc17.net> writes:

> The indentation in CPerl mode is buggy on sub, even with the default
> configuration (emacs -Q). Open the following file:
>
> ----------------------------------------
> #!/usr/bin/env perl
> # -*- mode: cperl -*-
>
> sub foo
>   {
>   }
>
> sub bar
>   {
>   }
> ----------------------------------------
>
> and hit the [TAB] key over the "sub bar" line. This line is indented
> by 2 columns instead of being left on the first column. More generally
> this happens on all subs except the first one.
>
> [TAB] on the '{' of sub bar (line 9 of the script) gives a 4-column
> indentation instead of 2, but this may be a consequence of the above
> problem.

I can reproduce this on Emacs 26.1.

> Other indentation bugs:
>
> ----------------------------------------
> #!/usr/bin/env perl
> # -*- mode: cperl -*-
>
> while (<>)
>   {
>     m:^  \d+ p:
>       or die;
>     m:^  \d+ :
>       or die;
>   }
> ----------------------------------------

I can reproduce this too.

Best regards,
Stefan Kangas

bug#11733: Indentation has been fixed in the master branch.

[Harald Jörg]

Eventually, the reworking of the indentation code allows to fix these
bugs (again, thanks for the clear recipes).

The first example will now be indented like this:
--------------------------------------------------
#!/usr/bin/env perl
# -*- mode: cperl -*-

sub foo
{
}

sub bar
{
}
--------------------------------------------------

This is in line with the Perl style guide
https://perldoc.perl.org/perlstyle.

The second example is a masterpiece of edge cases:
--------------------------------------------------
#!/usr/bin/env perl
# -*- mode: cperl -*-

while (<>)
  {
    m:^  \d+ p:
      or die;
    m:^  \d+ :
      or die;
  }
--------------------------------------------------
The strings 'm:' and 'p:' look like labels, and cperl-mode must take
extra measures to detect these situations.  This is now done.  When
indented line-by-line, cperl-mode will now the leave the indentation
unchanged.

cperl-mode.el from the repository works with Emacs versions 27 and
newer.

Therefore, I am declaring this bug "done".

-- 
Cheers,
haj