(Faset): Adjust the way to check byte-combining

possibility for the new handling of multibyte sequence.

1 files changed, 8 insertions, 7 deletions

diff --git a/src/data.c b/src/data.c
index a7e16c93abb..c1cfb817d6a 100644
--- a/src/data.c
+++ b/src/data.c
@@ -1859,13 +1859,14 @@ IDX starts at 0.")
         error ("Attempt to change byte length of a string");
 
       /* We can't accept a change causing byte combining.  */
-      if ((idxval > 0 && !CHAR_HEAD_P (*str)
-           && (prev_byte = string_char_to_byte (array, idxval - 1),
-               (prev_byte + 1 < idxval_byte
-                || (p[-1] >= 0x80 && p[-1] < 0xA0))))
-          || (idxval < XSTRING (array)->size - 1
-              && (*str >=0x80 && *str < 0xA0)
-              && !CHAR_HEAD_P (p[actual_len])))
+      if (!ASCII_BYTE_P (*str)
+          && ((idxval > 0 && !CHAR_HEAD_P (*str)
+               && (prev_byte = string_char_to_byte (array, idxval - 1),
+                   BYTES_BY_CHAR_HEAD (XSTRING (array)->data[prev_byte])
+                   > idxval_byte - prev_byte))
+              || (idxval < XSTRING (array)->size - 1
+                  && !CHAR_HEAD_P (p[actual_len])
+                  && new_len < BYTES_BY_CHAR_HEAD (*str))))
         error ("Attempt to change char length of a string");
       while (new_len--)
         *p++ = *str++;