GNU bug report logs - #78117
Improve c-ts-mode--c-or-c++-regexp

Previous Next

Full log

Message #14 received at 78117 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Sergey Abdulov <tidesmain <at> gmail.com>
Cc: 78117 <at> debbugs.gnu.org
Subject: Re: bug#78117: Improve c-ts-mode--c-or-c++-regexp
Date: Tue, 29 Apr 2025 08:15:44 +0300

> From: Sergey Abdulov <tidesmain <at> gmail.com>
> Date: Mon, 28 Apr 2025 22:46:01 +0500
> Cc: 78117 <at> debbugs.gnu.org
> 
> > That's not a good idea, because many header files are basically C
> > code, but use __cplusplus condition to allow C++ code include the
> > header file.
> 
> I mean, after `__cplusplus` check usually comes `extern "C"`
> which is not C and won't compile with GCC.
> But you have a point so I won't argue.
> 
> > That could be unreliable, I'm afraid.
> 
> Not sure why. Is there any conflict with C by
> matching, say, "operator<" in your opinion?

The search for this should take care not to produce false positives,
which might not be easy.  As a trivial example, it should not match
inside comments and strings, and not inside preprocessor directives
that are never true, like "#if 0" or somesuch.

Feel free to submit patches which would search for patterns that are
telltale C++, but I think it is not a coincidence that neither CC Mode
nor c-ts-mode go beyond very simple checks, and leave the rest to the
mode cookie.  (Btw, you could also solve this for an entire directory
using a .dir-locals.el file.  GDB sources do that, for example.)

> > Please submit a separate bug about that, with the details: where in
> > that file do you see the incorrect highlighting after switching the
> > mode.
> 
> Working on that. It turns out the issue is still there even if loading
> straight into c++-ts-mode. Random curly braces get
> `font-lock-warning-face` for no apparent reason.
> I'll try to narrow it down as much as possible and report it.

This could be some issue with the version of the C++ grammar library
you have.  Maybe it's too old, or too new with changes that Emacs did
not yet incorporate.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.