bug#73778: 30.0.91; cpp-ts-mode indentation never finishes

bug#73778: 30.0.91; cpp-ts-mode indentation never finishes

[Augustin Chéneau via Bug reports for GNU Emacs, the Swiss army knife of text editors]

--text follows this line--

In c++-ts-mode, there is a bug when I indent a line with <tab>.

This is trivially reproducible with the below code:

int func() {
	int a;
	int b;
     }

Place your point before "int b;", press <tab>, and the indentation
process never finishes.

This is caused by an error in c-ts-mode--anchor-prev-sibling, as the
condition of the last "or" in the function has incorrect
delimitation. Which means that the "if" will run the second test on
success, which then cause the function to be stuck in an infinite loop.

I would gladly send you a patch, but I've been stuck in the legal limbo 
of the copyright assignment for months now and I cannot contribute to
GNU Emacs (or any GNU project for the matter).

I hope my description will be enough.




In GNU Emacs 30.0.91 (build 6, x86_64-pc-linux-gnu, GTK+ Version
  3.24.43, cairo version 1.18.2) of 2024-10-12 built on inspiron-5567
Repository revision: 0f8f0773183a07a229b23d3f970723ceb9585aef
Repository branch: makepkg
Windowing system distributor 'The X.Org Foundation', version 11.0.12401003
System Description: Arch Linux

Configured using:
  'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
  --localstatedir=/var --mandir=/usr/share/man --with-gameuser=:games
  --with-modules --without-libotf --without-m17n-flt --without-gconf
  --with-native-compilation=yes --with-native-compilation=aot
  --with-xinput2 --with-x-toolkit=gtk3 --without-xaw3d --with-sound=no
  --with-tree-sitter --without-gpm --without-compress-install
  '--program-transform-name=s/\([ec]tags\)/\1.emacs/'
  'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -fexceptions
  -Wp,-D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security
  -fstack-clash-protection -fcf-protection'
  LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'

Configured features:
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LCMS2 LIBSYSTEMD LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG
RSVG SECCOMP SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER WEBP
X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB

Important settings:
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Major mode: ELisp/l

Minor modes in effect:
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Load-path shadows:
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/home/arch-aug/.config/emacs/straight/build/soap-client/soap-inspect 
hides /usr/share/emacs/30.0.91/lisp/net/soap-inspect
/home/arch-aug/.config/emacs/straight/build/soap-client/soap-client 
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/home/arch-aug/.config/emacs/straight/build/seq/seq hides 
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/home/arch-aug/.config/emacs/straight/build/let-alist/let-alist hides 
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/home/arch-aug/.config/emacs/straight/build/compat/compat hides 
/usr/share/emacs/30.0.91/lisp/emacs-lisp/compat

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bug#73778: 30.0.91; cpp-ts-mode indentation never finishes

[Eli Zaretskii]

> Date: Sat, 12 Oct 2024 21:20:47 +0200
> From:  Augustin Chéneau (BTuin) via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> In c++-ts-mode, there is a bug when I indent a line with <tab>.
> 
> This is trivially reproducible with the below code:
> 
> int func() {
> 	int a;
> 	int b;
>      }
> 
> Place your point before "int b;", press <tab>, and the indentation
> process never finishes.
> 
> This is caused by an error in c-ts-mode--anchor-prev-sibling, as the
> condition of the last "or" in the function has incorrect
> delimitation. Which means that the "if" will run the second test on
> success, which then cause the function to be stuck in an infinite loop.
> 
> I would gladly send you a patch, but I've been stuck in the legal limbo 
> of the copyright assignment for months now and I cannot contribute to
> GNU Emacs (or any GNU project for the matter).
> 
> I hope my description will be enough.

I cannot reproduce this on the latest emacs-30 branch, perhaps because
changes were installed in the function you mention two days after you
have built your Emacs.  Can you try the latest emacs-30 branch and see
if the problem still persists?

Thanks.