Fix composition bug caused by off-by-1 typo

* src/xdisp.c (x_produce_glyphs): Fix off-by-one typo when
computing composition glyph (Bug#23938).

diff --git a/src/xdisp.c b/src/xdisp.c
index d5ffb25eb18ab68e320d6e41dba607c494670d18..14d6f8fcf93fdca4c78b85abd0af13fc3bd48118 100644 (file)
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -27369,8 +27369,8 @@ x_produce_glyphs (struct it *it)
 
          eassume (0 < glyph_len); /* See Bug#8512.  */
          do
-           c = COMPOSITION_GLYPH (cmp, --glyph_len);
-         while (c == '\t' && 0 < glyph_len);
+           c = COMPOSITION_GLYPH (cmp, glyph_len - 1);
+         while (c == '\t' && 0 < --glyph_len);
 
          bool right_padded = glyph_len < cmp->glyph_len;
          for (i = 0; i < glyph_len; i++)