bug#18072: 24.3; cc-mode indentation is broken

bug#18072: 24.3; cc-mode indentation is broken

[Juhani Åhman]

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Please write in English if possible, as the Emacs maintainers
usually do not have translators for other languages.

Please describe exactly what actions triggered the bug, and
the precise symptoms of the bug. If you can, give a recipe
starting from `emacs -Q':

I can't reliably reproduce the bug.
All I can say that the auto-indentation thingymajig in cc-mode stops 
working at
random every 5-15 minutes or so.
I can get it working again by reloading the file I am editing.
When the indentation is broken, pressing enter will leave no indentation
space for braces and such.

it looks like this

if(1) {
foo();
bar();
zot();
}

when it should look like this

if(1) {
     foo();
     bar();
     zot();
}

I'm pretty sure the indentation was working in some previous version,
about two years ago or so, but not in any of the newer versions of Emacs.


If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
`bt full' and `xbacktrace'.
For information about debugging Emacs, please read the file
/usr/share/emacs/24.3/etc/DEBUG.


In GNU Emacs 24.3.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.12.2)
of 2014-06-11 on var-lib-archbuild-staging-x86_64-jgc
Windowing system distributor `The X.Org Foundation', version 11.0.11502000
Configured using:
`configure '--prefix=/usr' '--sysconfdir=/etc' '--libexecdir=/usr/lib'
'--localstatedir=/var' '--with-x-toolkit=gtk3' '--with-xft'
'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong
--param=ssp-buffer-size=4'
'LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro'
'CPPFLAGS=-D_FORTIFY_SOURCE=2''

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

Major mode: Lisp Interaction

Minor modes in effect:
electric-indent-mode: t
cua-mode: t
global-subword-mode: t
subword-mode: t
show-paren-mode: t
global-hl-line-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:
M-x c o - m
C-a C-k C-g M-x r e o
p e p o
r

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Loading 
/home/fzzy/.emacs.d/session.10ded9d363000140534073900000004430047...done
Restored session data
Making completion list... [3 times]
Quit
Making completion list... [2 times]

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message idna format-spec
rfc822 mml 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 help-mode easymenu electric preview-latex
tex-site auto-loads cc-styles cc-align cc-engine cc-vars cc-defs
bison-mode-autoloads glsl-mode-autoloads go-mode-autoloads package
cua-base subword bs paren edmacro kmacro hl-line delsel server time-date
tooltip ediff-hook vc-hooks lisp-float-type mwheel x-win x-dnd tool-bar
dnd fontset image regexp-opt fringe tabulated-list newcomment 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 macroexp 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)

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bug#18072: 24.3; cc-mode indentation is broken

[Stefan Kangas]

Juhani Åhman <juhanipm@gmail.com> writes:

> I can't reliably reproduce the bug. 
> All I can say that the auto-indentation thingymajig in cc-mode stops working at 
> random every 5-15 minutes or so. 
> I can get it working again by reloading the file I am editing. 
> When the indentation is broken, pressing enter will leave no indentation 
> space for braces and such. 
>
> it looks like this 
>
> if(1) { 
> foo(); 
> bar(); 
> zot(); 
> } 
>
> when it should look like this 
>
> if(1) { 
>     foo(); 
>     bar(); 
>     zot(); 
> } 
>
> I'm pretty sure the indentation was working in some previous version, 
> about two years ago or so, but not in any of the newer versions of Emacs.

I'm not seeing this here.  Can you reproduce this when running under
"emacs -Q"?

Best regards,
Stefan Kangas

bug#18072: 24.3; cc-mode indentation is broken

[Alan Mackenzie]

Hello, Stefan and Juhani.

In article <mailman.384.1572692163.13325.bug-gnu-emacs@gnu.org> you wrote:
> Juhani Åhman <juhanipm@gmail.com> writes:

>> I can't reliably reproduce the bug. 
>> All I can say that the auto-indentation thingymajig in cc-mode stops working at 
>> random every 5-15 minutes or so. 
>> I can get it working again by reloading the file I am editing. 
>> When the indentation is broken, pressing enter will leave no indentation 
>> space for braces and such. 
>>
>> it looks like this 
>>
>> if(1) { 
>> foo(); 
>> bar(); 
>> zot(); 
>> } 
>>
>> when it should look like this 
>>
>> if(1) { 
>>     foo(); 
>>     bar(); 
>>     zot(); 
>> } 
>>
>> I'm pretty sure the indentation was working in some previous version, 
>> about two years ago or so, but not in any of the newer versions of Emacs.

Is this C++ Mode, by any chance?

> I'm not seeing this here.  Can you reproduce this when running under
> "emacs -Q"?

This looks like having the same cause as bug #37910 "CC Mode 5.33.2
(C++//l); CC-mode inconsistently indents everything as topmost-intro
after a while".

I'm pretty sure it's a defect in a particular CC Mode cache (the "state
cache"), which tracks parentheses, braces, and brackets containing and
near point.  Somehow, it's missing the critical {, believing that
foo();, etc., are at top level.  A C-c C-s on that line would likely
show "topmost-intro".

> Best regards,
> Stefan Kangas

-- 
Alan Mackenzie (Nuremberg, Germany).

bug#18072: 24.3; cc-mode indentation is broken

[Stefan Kangas]

Hi Alan,

Alan Mackenzie <acm@muc.de> writes:

> Is this C++ Mode, by any chance?

I'm not sure which one to use to reproduce it.  I'm hoping Juhani will
be able to tell us.

> This looks like having the same cause as bug #37910 "CC Mode 5.33.2
> (C++//l); CC-mode inconsistently indents everything as topmost-intro
> after a while".
>
> I'm pretty sure it's a defect in a particular CC Mode cache (the "state
> cache"), which tracks parentheses, braces, and brackets containing and
> near point.  Somehow, it's missing the critical {, believing that
> foo();, etc., are at top level.  A C-c C-s on that line would likely
> show "topmost-intro".

Do you think that these two bugs should be merged?

Best regards,
Stefan Kangas

bug#18072: 24.3; cc-mode indentation is broken

[Juhani Ahman]

Hi

It definitely happened with C++ at least.
Don't remember if it happened with C too.
It's been awhile.

> On 10 November 2019 at 23:13 Stefan Kangas <stefan@marxist.se> wrote:
> 
> 
> Hi Alan,
> 
> Alan Mackenzie <acm@muc.de> writes:
> 
> > Is this C++ Mode, by any chance?
> 
> I'm not sure which one to use to reproduce it.  I'm hoping Juhani will
> be able to tell us.
> 
> > This looks like having the same cause as bug #37910 "CC Mode 5.33.2
> > (C++//l); CC-mode inconsistently indents everything as topmost-intro
> > after a while".
> >
> > I'm pretty sure it's a defect in a particular CC Mode cache (the "state
> > cache"), which tracks parentheses, braces, and brackets containing and
> > near point.  Somehow, it's missing the critical {, believing that
> > foo();, etc., are at top level.  A C-c C-s on that line would likely
> > show "topmost-intro".
> 
> Do you think that these two bugs should be merged?
> 
> Best regards,
> Stefan Kangas

bug#18072: 24.3; cc-mode indentation is broken

[Alan Mackenzie]

Hello, Stefan.

On Sun, Nov 10, 2019 at 22:13:00 +0100, Stefan Kangas wrote:
> Hi Alan,

> Alan Mackenzie <acm@muc.de> writes:

> > Is this C++ Mode, by any chance?

> I'm not sure which one to use to reproduce it.  I'm hoping Juhani will
> be able to tell us.

> > This looks like having the same cause as bug #37910 "CC Mode 5.33.2
> > (C++//l); CC-mode inconsistently indents everything as topmost-intro
> > after a while".

> > I'm pretty sure it's a defect in a particular CC Mode cache (the "state
> > cache"), which tracks parentheses, braces, and brackets containing and
> > near point.  Somehow, it's missing the critical {, believing that
> > foo();, etc., are at top level.  A C-c C-s on that line would likely
> > show "topmost-intro".

> Do you think that these two bugs should be merged?

I don't think the evidence is strong enough to do this, yet.  Not quite.

In the course of investigating #37910, I discovered a flaw whose effect
would be consistent with what we're seeing in #37910 and the current
bug.  I intend to commit a fix to this flaw, soon.  However, there's
more to #37910 than just that flaw, so #37910 is where I'm spending my
time at the moment.

> Best regards,
> Stefan Kangas

-- 
Alan Mackenzie (Nuremberg, Germany).