bug#29959: cc-mode: wrong indentation in absence of semicolon

bug#29959: cc-mode: wrong indentation in absence of semicolon

[Konstantin Kharlamov]

# Steps to reproduce:
1. Open emacs -Q test.c
2. Write the following:

int main() {
     int a,
}

3. put the caret after the comma symbol, and press enter, e.g. to
continue writing variables on the new line.

# Expected:
the new line alignment stands out with regard to the prev. line.

# Actual:
the new line aligned to the beginning of the prev. line.

# Workarounds:
Typing the following text:

int main() {
     int a,;
}

…then pressing enter right after the comma works as expected.

------------

In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.26)
  of 2017-12-15 built on constantine-N61Ja
Repository revision: 6c301afa70f6eac32ad1ce92412ea3cf6fcdeeca
Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
System Description: Arch Linux

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
  'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
  --localstatedir=/var --mandir=/usr/share/man --with-gameuser=:games
  --with-sound=alsa --with-xft --with-modules --with-x-toolkit=gtk3
  --without-gconf --without-gsettings --without-gpm --without-m17n-flt
  --without-imagemagick 'CFLAGS=-flto=2 -march=native -O3 -pipe
  -fno-stack-protector -fweb -fno-semantic-interposition
  -fmerge-all-constants' 'LDFLAGS=-flto=2 -O3 -march=native -fweb
  -fno-semantic-interposition -fmerge-all-constants -floop-nest-optimize
  -Wl,--sort-common,-z,relro -fuse-ld=gold''

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND DBUS NOTIFY ACL GNUTLS LIBXML2 FREETYPE
LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 MODULES LIBSYSTEMD JSON
LCMS2

Important settings:
   value of $LC_CTYPE: ru_RU.UTF-8
   value of $LC_TIME: ru_RU.UTF-8
   value of $LANG: en_US.UTF-8
   value of $XMODIFIERS: @im=none
   locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

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

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny seq byte-opt gv
bytecomp byte-compile cconv cl-loaddefs cl-lib dired dired-loaddefs
format-spec rfc822 mml easymenu mml-sec password-cache epa derived epg
epg-config gnus-util rmail rmail-loaddefs mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils elec-pair time-date
mule-util cyril-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel term/x-win x-win term/common-win x-dnd tool-bar
dnd fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode elisp-mode lisp-mode prog-mode register page menu-bar
rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock
syntax facemenu font-core term/tty-colors frame cl-generic 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 charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray 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 lcms2
dynamic-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty make-network-process emacs)

Memory information:
((conses 16 95121 11339)
  (symbols 48 20190 1)
  (miscs 40 48 119)
  (strings 32 28421 1060)
  (string-bytes 1 750170)
  (vectors 16 14089)
  (vector-slots 8 494084 10026)
  (floats 8 49 212)
  (intervals 56 239 0)
  (buffers 992 11))

bug#29959: cc-mode: wrong indentation in absence of semicolon

[Konstantin Kharlamov]

Just tested with current git, the problem is still present.

I am almost sure this is a regression, I don't remember having that 
problem before. The real-world consequences are just too annoying for it 
to go unnoticed — basically, every time I'm typing variables indentation 
just doesn't work. And I also seem to remember a few irrelevant 
situations where I was typing conditions with the like results.

On 03.01.2018 09:02, Konstantin Kharlamov wrote:
> # Steps to reproduce:
> 1. Open emacs -Q test.c
> 2. Write the following:
> 
> int main() {
>      int a,
> }
> 
> 3. put the caret after the comma symbol, and press enter, e.g. to
> continue writing variables on the new line.
> 
> # Expected:
> the new line alignment stands out with regard to the prev. line.
> 
> # Actual:
> the new line aligned to the beginning of the prev. line.
> 
> # Workarounds:
> Typing the following text:
> 
> int main() {
>      int a,;
> }
> 
> …then pressing enter right after the comma works as expected.
> 
> ------------
> 
> In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.26)
>   of 2017-12-15 built on constantine-N61Ja
> Repository revision: 6c301afa70f6eac32ad1ce92412ea3cf6fcdeeca
> Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
> System Description: Arch Linux
> 
> Recent messages:
> For information about GNU Emacs and the GNU system, type C-h C-a.
> 
> Configured using:
>   'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
>   --localstatedir=/var --mandir=/usr/share/man --with-gameuser=:games
>   --with-sound=alsa --with-xft --with-modules --with-x-toolkit=gtk3
>   --without-gconf --without-gsettings --without-gpm --without-m17n-flt
>   --without-imagemagick 'CFLAGS=-flto=2 -march=native -O3 -pipe
>   -fno-stack-protector -fweb -fno-semantic-interposition
>   -fmerge-all-constants' 'LDFLAGS=-flto=2 -O3 -march=native -fweb
>   -fno-semantic-interposition -fmerge-all-constants -floop-nest-optimize
>   -Wl,--sort-common,-z,relro -fuse-ld=gold''
> 
> Configured features:
> XPM JPEG TIFF GIF PNG RSVG SOUND DBUS NOTIFY ACL GNUTLS LIBXML2 FREETYPE
> LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 MODULES LIBSYSTEMD JSON
> LCMS2
> 
> Important settings:
>    value of $LC_CTYPE: ru_RU.UTF-8
>    value of $LC_TIME: ru_RU.UTF-8
>    value of $LANG: en_US.UTF-8
>    value of $XMODIFIERS: @im=none
>    locale-coding-system: utf-8-unix
> 
> Major mode: Lisp Interaction
> 
> Minor modes in effect:
>    tooltip-mode: t
>    global-eldoc-mode: t
>    eldoc-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
>    auto-composition-mode: t
>    auto-encryption-mode: t
>    auto-compression-mode: t
>    line-number-mode: t
>    transient-mark-mode: t
> 
> Load-path shadows:
> None found.
> 
> Features:
> (shadow sort mail-extr emacsbug message rmc puny seq byte-opt gv
> bytecomp byte-compile cconv cl-loaddefs cl-lib dired dired-loaddefs
> format-spec rfc822 mml easymenu mml-sec password-cache epa derived epg
> epg-config gnus-util rmail rmail-loaddefs mm-decode mm-bodies mm-encode
> mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047
> rfc2045 ietf-drums mm-util mail-prsvr mail-utils elec-pair time-date
> mule-util cyril-util tooltip eldoc electric uniquify ediff-hook vc-hooks
> lisp-float-type mwheel term/x-win x-win term/common-win x-dnd tool-bar
> dnd fontset image regexp-opt fringe tabulated-list replace newcomment
> text-mode elisp-mode lisp-mode prog-mode register page menu-bar
> rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock
> syntax facemenu font-core term/tty-colors frame cl-generic 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 charscript charprop
> case-table epa-hook jka-cmpr-hook help simple abbrev obarray 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 lcms2
> dynamic-setting font-render-setting move-toolbar gtk x-toolkit x
> multi-tty make-network-process emacs)
> 
> Memory information:
> ((conses 16 95121 11339)
>   (symbols 48 20190 1)
>   (miscs 40 48 119)
>   (strings 32 28421 1060)
>   (string-bytes 1 750170)
>   (vectors 16 14089)
>   (vector-slots 8 494084 10026)
>   (floats 8 49 212)
>   (intervals 56 239 0)
>   (buffers 992 11))

bug#29959: cc-mode: wrong indentation in absence of semicolon

[Alan Mackenzie]

Hello, Konstantin.

On Sat, Jan 13, 2018 at 14:11:31 +0300, Konstantin Kharlamov wrote:
> Just tested with current git, the problem is still present.

> I am almost sure this is a regression, I don't remember having that 
> problem before. The real-world consequences are just too annoying for it 
> to go unnoticed — basically, every time I'm typing variables indentation 
> just doesn't work. And I also seem to remember a few irrelevant 
> situations where I was typing conditions with the like results.

The problem originates in a new feature, C99 compound literals, which was
committed on 2017-11-10.  This detects brace blocks (meaning something
like the initialisation of a struct) in the middle of executable code,
but it is clear the test for such a brace block isn't rigorous enough,
since even function blocks are being mistaken for them.

> On 03.01.2018 09:02, Konstantin Kharlamov wrote:
> > # Steps to reproduce:
> > 1. Open emacs -Q test.c
> > 2. Write the following:

> > int main() {
> >      int a,
> > }

> > 3. put the caret after the comma symbol, and press enter, e.g. to
> > continue writing variables on the new line.

> > # Expected:
> > the new line alignment stands out with regard to the prev. line.

> > # Actual:
> > the new line aligned to the beginning of the prev. line.

> > # Workarounds:
> > Typing the following text:

> > int main() {
> >      int a,;
> > }

> > …then pressing enter right after the comma works as expected.

At the moment, the bug you're seeing is triggered by CC Mode checking for
commas and semicolons in blocks; if the last such delimiter is a comma,
the block is taken as a brace block.  So a workaround, for the moment, is
to ensure that you have a semicolon in each block as the last delimiter
there.

I will be working on fixing this bug.  Thanks for taking the trouble to
report it.

> > ------------

> > In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.26)
> >   of 2017-12-15 built on constantine-N61Ja
> > Repository revision: 6c301afa70f6eac32ad1ce92412ea3cf6fcdeeca
> > Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
> > System Description: Arch Linux

[ .... ]

-- 
Alan Mackenzie (Nuremberg, Germany).

bug#29959: cc-mode: wrong indentation in absence of semicolon

[Alan Mackenzie]

Hello again, Konstantin.

On Sat, Jan 13, 2018 at 20:37:52 +0000, Alan Mackenzie wrote:
> On Sat, Jan 13, 2018 at 14:11:31 +0300, Konstantin Kharlamov wrote:
> > Just tested with current git, the problem is still present.

> > I am almost sure this is a regression, I don't remember having that 
> > problem before. The real-world consequences are just too annoying for it 
> > to go unnoticed — basically, every time I'm typing variables indentation 
> > just doesn't work. And I also seem to remember a few irrelevant 
> > situations where I was typing conditions with the like results.

> The problem originates in a new feature, C99 compound literals, which was
> committed on 2017-11-10.  This detects brace blocks (meaning something
> like the initialisation of a struct) in the middle of executable code,
> but it is clear the test for such a brace block isn't rigorous enough,
> since even function blocks are being mistaken for them.

The new feature, C99 compound literals, has been removed from the
emacs-26 branch, so as to avoid delaying the relase process for that
branch.  The commit has hash 36edb6cb97ce3d53543c87643077d270bb5bdfd1,
and it should apply without problems to the master branch.

It is to be hoped that a more elaborate and more correct solution will
be found soon for the master branch.

> > On 03.01.2018 09:02, Konstantin Kharlamov wrote:
> > > # Steps to reproduce:
> > > 1. Open emacs -Q test.c
> > > 2. Write the following:

> > > int main() {
> > >      int a,
> > > }

> > > 3. put the caret after the comma symbol, and press enter, e.g. to
> > > continue writing variables on the new line.

> > > # Expected:
> > > the new line alignment stands out with regard to the prev. line.

> > > # Actual:
> > > the new line aligned to the beginning of the prev. line.

> > > # Workarounds:
> > > Typing the following text:

> > > int main() {
> > >      int a,;
> > > }

> > > …then pressing enter right after the comma works as expected.

> > > ------------

> > > In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.26)
> > >   of 2017-12-15 built on constantine-N61Ja
> > > Repository revision: 6c301afa70f6eac32ad1ce92412ea3cf6fcdeeca
> > > Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
> > > System Description: Arch Linux

> [ .... ]

-- 
Alan Mackenzie (Nuremberg, Germany).

bug#29959: cc-mode: wrong indentation in absence of semicolon

[Konstantin Kharlamov]

Cool, thanks, I applied it locally, works for me!

On 18.01.2018 21:41, Alan Mackenzie wrote:
> Hello again, Konstantin.
> 
> On Sat, Jan 13, 2018 at 20:37:52 +0000, Alan Mackenzie wrote:
>> On Sat, Jan 13, 2018 at 14:11:31 +0300, Konstantin Kharlamov wrote:
>>> Just tested with current git, the problem is still present.
> 
>>> I am almost sure this is a regression, I don't remember having that
>>> problem before. The real-world consequences are just too annoying for it
>>> to go unnoticed — basically, every time I'm typing variables indentation
>>> just doesn't work. And I also seem to remember a few irrelevant
>>> situations where I was typing conditions with the like results.
> 
>> The problem originates in a new feature, C99 compound literals, which was
>> committed on 2017-11-10.  This detects brace blocks (meaning something
>> like the initialisation of a struct) in the middle of executable code,
>> but it is clear the test for such a brace block isn't rigorous enough,
>> since even function blocks are being mistaken for them.
> 
> The new feature, C99 compound literals, has been removed from the
> emacs-26 branch, so as to avoid delaying the relase process for that
> branch.  The commit has hash 36edb6cb97ce3d53543c87643077d270bb5bdfd1,
> and it should apply without problems to the master branch.
> 
> It is to be hoped that a more elaborate and more correct solution will
> be found soon for the master branch.
> 
>>> On 03.01.2018 09:02, Konstantin Kharlamov wrote:
>>>> # Steps to reproduce:
>>>> 1. Open emacs -Q test.c
>>>> 2. Write the following:
> 
>>>> int main() {
>>>>       int a,
>>>> }
> 
>>>> 3. put the caret after the comma symbol, and press enter, e.g. to
>>>> continue writing variables on the new line.
> 
>>>> # Expected:
>>>> the new line alignment stands out with regard to the prev. line.
> 
>>>> # Actual:
>>>> the new line aligned to the beginning of the prev. line.
> 
>>>> # Workarounds:
>>>> Typing the following text:
> 
>>>> int main() {
>>>>       int a,;
>>>> }
> 
>>>> …then pressing enter right after the comma works as expected.
> 
>>>> ------------
> 
>>>> In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.26)
>>>>    of 2017-12-15 built on constantine-N61Ja
>>>> Repository revision: 6c301afa70f6eac32ad1ce92412ea3cf6fcdeeca
>>>> Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
>>>> System Description: Arch Linux
> 
>> [ .... ]
> 

bug#29959: cc-mode: wrong indentation in absence of semicolon

[Konstantin Kharlamov]

Sorry, I mean, not cool that it doesn't work, but cool there's a workaround.

On side note — though I am not experienced in elisp — I think it'd be 
nice to add a comment in the removed code that it's looking for C99 
compound literals. Otherwise I personally struggle to understand what's 
being looked up there. In fact, whole file doesn't mention sentence "C99 
compound literals" anywhere.

On 18.01.2018 22:08, Konstantin Kharlamov wrote:
> Cool, thanks, I applied it locally, works for me!
> 
> On 18.01.2018 21:41, Alan Mackenzie wrote:
>> Hello again, Konstantin.
>>
>> On Sat, Jan 13, 2018 at 20:37:52 +0000, Alan Mackenzie wrote:
>>> On Sat, Jan 13, 2018 at 14:11:31 +0300, Konstantin Kharlamov wrote:
>>>> Just tested with current git, the problem is still present.
>>
>>>> I am almost sure this is a regression, I don't remember having that
>>>> problem before. The real-world consequences are just too annoying 
>>>> for it
>>>> to go unnoticed — basically, every time I'm typing variables 
>>>> indentation
>>>> just doesn't work. And I also seem to remember a few irrelevant
>>>> situations where I was typing conditions with the like results.
>>
>>> The problem originates in a new feature, C99 compound literals, which 
>>> was
>>> committed on 2017-11-10.  This detects brace blocks (meaning something
>>> like the initialisation of a struct) in the middle of executable code,
>>> but it is clear the test for such a brace block isn't rigorous enough,
>>> since even function blocks are being mistaken for them.
>>
>> The new feature, C99 compound literals, has been removed from the
>> emacs-26 branch, so as to avoid delaying the relase process for that
>> branch.  The commit has hash 36edb6cb97ce3d53543c87643077d270bb5bdfd1,
>> and it should apply without problems to the master branch.
>>
>> It is to be hoped that a more elaborate and more correct solution will
>> be found soon for the master branch.
>>
>>>> On 03.01.2018 09:02, Konstantin Kharlamov wrote:
>>>>> # Steps to reproduce:
>>>>> 1. Open emacs -Q test.c
>>>>> 2. Write the following:
>>
>>>>> int main() {
>>>>>       int a,
>>>>> }
>>
>>>>> 3. put the caret after the comma symbol, and press enter, e.g. to
>>>>> continue writing variables on the new line.
>>
>>>>> # Expected:
>>>>> the new line alignment stands out with regard to the prev. line.
>>
>>>>> # Actual:
>>>>> the new line aligned to the beginning of the prev. line.
>>
>>>>> # Workarounds:
>>>>> Typing the following text:
>>
>>>>> int main() {
>>>>>       int a,;
>>>>> }
>>
>>>>> …then pressing enter right after the comma works as expected.
>>
>>>>> ------------
>>
>>>>> In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 
>>>>> 3.22.26)
>>>>>    of 2017-12-15 built on constantine-N61Ja
>>>>> Repository revision: 6c301afa70f6eac32ad1ce92412ea3cf6fcdeeca
>>>>> Windowing system distributor 'The X.Org Foundation', version 
>>>>> 11.0.11906000
>>>>> System Description: Arch Linux
>>
>>> [ .... ]
>>

bug#29959: cc-mode: wrong indentation in absence of semicolon

[Noam Postavsky]

tags 29959 fixed
close 29959 
quit

Alan Mackenzie <acm@muc.de> writes:

> The new feature, C99 compound literals, has been removed from the
> emacs-26 branch, so as to avoid delaying the relase process for that
> branch.  The commit has hash 36edb6cb97ce3d53543c87643077d270bb5bdfd1,
> and it should apply without problems to the master branch.
>
> It is to be hoped that a more elaborate and more correct solution will
> be found soon for the master branch.

Seems to be fixed on the master branch too by now.