From 00eb21c8979f4e53345fdc021d32307d102afda9 Mon Sep 17 00:00:00 2001
From: Eli Zaretskii <eliz@gnu.org>
Date: Sat, 9 Oct 2021 14:38:06 +0300
Subject: [PATCH] ; * src/dispextern.h (struct glyph_string): Comment on
 NCHARS.  (Bug#51105)

---
 src/dispextern.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/dispextern.h b/src/dispextern.h
index 6aefe43e195..08dac5d4557 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -1326,7 +1326,9 @@ struct glyph_string
   /* The area within row.  */
   enum glyph_row_area area;
 
-  /* Characters to be drawn, and number of characters.  */
+  /* Characters to be drawn, and number of characters.  Note that
+     NCHARS can be zero if this is a composition glyph string, as
+     evidenced by FIRST_GLYPH->type.  */
   unsigned *char2b;
   int nchars;
 
-- 
2.39.2