Fix c-ts-mode indentation

Mentioned in bug#61893, although not the subject of it.

* lisp/progmodes/c-ts-mode.el:
(c-ts-mode--anchor-prev-sibling): Fix the child index for preproc_else
and preproc_elif case.
* test/lisp/progmodes/c-ts-mode-resources/indent-preproc.erts:
New test.

1 files changed, 16 insertions, 0 deletions

diff --git a/test/lisp/progmodes/c-ts-mode-resources/indent-preproc.erts b/test/lisp/progmodes/c-ts-mode-resources/indent-preproc.erts
index 0f9256ad984..a82596e0010 100644
--- a/test/lisp/progmodes/c-ts-mode-resources/indent-preproc.erts
+++ b/test/lisp/progmodes/c-ts-mode-resources/indent-preproc.erts
@@ -78,3 +78,19 @@ free_glyph_pool (struct glyph_pool *pool)
     }
 }
 =-=-=
+
+Name: Prev-Sibling Plus Preproc
+
+=-=-=
+int main() {
+#ifdef MSDOS
+  f->output_data.tty = &the_only_tty_output;
+  f->output_data.tty->display_info = &the_only_display_info;
+#else
+  if (f->output_method == output_termcap)
+    create_tty_output (f);
+#endif
+  t->display_info.tty->top_frame = selected_frame;
+  change_frame_size ();
+}
+=-=-=