GNU bug report logs - #64917
30.0.50; c-ts-mode throws warnings about missing cpp support

Previous Next

Full log

View this message in rfc822 format

From: Yuan Fu <casouri <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 64917 <at> debbugs.gnu.org, Robert Pluim <rpluim <at> gmail.com>
Subject: bug#64917: 30.0.50; c-ts-mode throws warnings about missing cpp support
Date: Sat, 29 Jul 2023 10:46:18 -0700

> On Jul 28, 2023, at 5:11 AM, Eli Zaretskii <eliz <at> gnu.org> wrote:
> 
> tags 64917 notabug
> thanks
> 
>> From: Robert Pluim <rpluim <at> gmail.com>
>> Date: Fri, 28 Jul 2023 11:14:15 +0200
>> 
>> I built master with tree-sitter support, and installed the c-language
>> grammar using M-x treesit-install-language-grammar. I have
>> libtree-sitter-c.so in ~/.emacs.d/tree-sitter
>> 
>> I restarted emacs, visited src/xdisp.c, and did M-x c-ts-mode, which
>> popped up a *Warnings* buffer containing:
>> 
>> ⛔ Warning (treesit): Cannot activate tree-sitter, because language grammar for cpp is unavailable (not-found): (libtree-sitter-cpp libtree-sitter-cpp.0 libtree-sitter-cpp.0.0 libtree-sitter-cpp.so libtree-sitter-cpp.so.0 libtree-sitter-cpp.so.0.0) No such file or directory
>> ⛔ Warning (treesit): Cannot activate tree-sitter, because language grammar for cpp is unavailable (not-found): (libtree-sitter-cpp libtree-sitter-cpp.0 libtree-sitter-cpp.0.0 libtree-sitter-cpp.so libtree-sitter-cpp.so.0 libtree-sitter-cpp.so.0.0) No such file or directory
>> 
>> which is less than desirable (althoug `major-mode' is c-ts-mode, so I
>> guess things worked)
> 
> Please install the C++ grammar as well.  Those two go together because
> some *.h files could be C or C++, and we can only test that at run
> time.

For future reference, that’s true but not the whole picture. The warning is caused by the call to (treesit-ready-p ‘cpp) at the end of c-ts-mode.el:

(if (treesit-ready-p 'cpp)
    (add-to-list 'auto-mode-alist
                 '("\\(\\.ii\\|\\.\\(CC?\\|HH?\\)\\|\\.[ch]\\(pp\\|xx\\|\\+\\+\\)\\|\\.\\(cc\\|hh\\)\\)\\'"
                   . c++-ts-mode)))

There was a discussion on whether we want to use (treesit-ready-p ‘cpp t) which tests for the availability of cpp grammar but doesn’t raise a warning. And your decision was to keep the warning, IIRC.

And my understanding is that these code that modifies auto-mode-alist whenever c-ts-mode.el is loaded are temporary for Emacs 29, and in the future might be removed. If they are removed, the warning will be gone.

Yuan

Previous Next

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