bug#81588: 32.0.50; c-ts-mode is indenting concatenated string literals

Hello

To reproduce this problem, write a c-file with something like the
following code making sure c-ts-mode is NOT enabled, using emacs -Q:

char *lines =
  "line1\n"
  "line2\n";

Observe how hitting TAB on respective line is not changing the
indentation.

Now turn on c-ts-mode and observe how hitting TAB will change the
indentation to this.

char *lines =
  "line1\n"
    "line2\n"

I would typically expect the c-mode behavior.

In bug#68493 I mentioned a diff that fixes this problem for me. I
thought I should present it here in its own bug report to be rejected
or accepted or something else. I attach the diff.

In GNU Emacs 32.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.49, cairo version 1.18.4) of 2026-08-09 built on fliptop2
Repository revision: b157d8e96a26e7509136bf93fad2c7ec49c0ee88
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101016
System Description: Debian GNU/Linux 13 (trixie)

diff --git a/lisp/progmodes/c-ts-mode.el b/lisp/progmodes/c-ts-mode.el
index 5f064716a89..fa09cb21b34 100644
--- a/lisp/progmodes/c-ts-mode.el
+++ b/lisp/progmodes/c-ts-mode.el
@@ -503,7 +503,8 @@ c-ts-mode--simple-indent-rules
                                 "enum_specifier"
                                 "union_specifier"
                                 "function_declarator"
-                                "template_declaration")))
+                                "template_declaration"
+                                "concatenated_string")))
             standalone-parent 0)
            ;; This is for the trailing-star stype:  int *
            ;;                                       func()