(lisp_string_width): Check multibyteness of STRING.

1 files changed, 13 insertions, 2 deletions

diff --git a/src/charset.c b/src/charset.c
index 2c985b14dbc..fb9804c0306 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -1344,6 +1344,10 @@ lisp_string_width (string, precision, nchars, nbytes)
 {
   int len = SCHARS (string);
   int len_byte = SBYTES (string);
+  /* This set multibyte to 0 even if STRING is multibyte when it
+     contains only ascii and eight-bit-graphic, but that's
+     intentional.  */
+  int multibyte = len < len_byte;
   const unsigned char *str = SDATA (string);
   int i = 0, i_byte = 0;
   int width = 0;
@@ -1366,8 +1370,12 @@ lisp_string_width (string, precision, nchars, nbytes)
         }
       else if (dp)
         {
-          int c = STRING_CHAR_AND_LENGTH (str + i_byte, len - i_byte, bytes);
+          int c;
 
+          if (multibyte)
+            c = STRING_CHAR_AND_LENGTH (str + i_byte, len - i_byte, bytes);
+          else
+            c = str[i_byte], bytes = 1;
           chars = 1;
           val = DISP_CHAR_VECTOR (dp, c);
           if (VECTORP (val))
@@ -1378,7 +1386,10 @@ lisp_string_width (string, precision, nchars, nbytes)
       else
         {
           chars = 1;
-          PARSE_MULTIBYTE_SEQ (str + i_byte, len_byte - i_byte, bytes);
+          if (multibyte)
+            PARSE_MULTIBYTE_SEQ (str + i_byte, len_byte - i_byte, bytes);
+          else
+            bytes = 1;
           thiswidth = ONE_BYTE_CHAR_WIDTH (str[i_byte]);
         }