[gcc r15-2457] dir-locals: apply our C settings in C++ also

[Arsen Arsenovic via Gcc-cvs]

https://gcc.gnu.org/g:ebf4f095568e8e4af042f3e5a8cb6558888d9172

commit r15-2457-gebf4f095568e8e4af042f3e5a8cb6558888d9172
Author: Arsen Arsenović <ar...@aarsen.me>
Date:   Wed Jul 31 16:53:35 2024 +0200

    dir-locals: apply our C settings in C++ also
    
    This also works with Emacs 30 Tree-Sitter C and C++ modes, as they are
    submodes.
    
    ChangeLog:
    
            * .dir-locals.el: Change c-mode to a list of C, C++ and ObjC
            modes that Emacs currently provides.

Diff:
---
 .dir-locals.el | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/.dir-locals.el b/.dir-locals.el
index fa031cbded99..2c12b3866633 100644
--- a/.dir-locals.el
+++ b/.dir-locals.el
@@ -18,6 +18,10 @@
              (tcl-continued-indent-level . 4)
              (indent-tabs-mode . t)))
  (nil . ((bug-reference-url-format . "https://gcc.gnu.org/PR%s";)))
+ ;; Please keep C and C++ in sync.
  (c-mode . ((c-file-style . "GNU")
            (indent-tabs-mode . t)
-           (fill-column . 79))))
+           (fill-column . 79)))
+ (c++-mode . ((c-file-style . "GNU")
+             (indent-tabs-mode . t)
+             (fill-column . 79))))