(Fdefine_coding_system_internal): Fix checking of ascii compatibility.

1 files changed, 7 insertions, 4 deletions

diff --git a/src/coding.c b/src/coding.c
index c153ebb1f3a..a7b4a7a4a75 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -8107,7 +8107,6 @@ usage: (define-coding-system-internal ...)  */)
 
   if (EQ (coding_type, Qcharset))
     {
-      Lisp_Object list;
       /* Generate a lisp vector of 256 elements.  Each element is nil,
          integer, or a list of charset IDs.
 
@@ -8119,8 +8118,10 @@ usage: (define-coding-system-internal ...)  */)
 
          If Nth element is a list of charset IDs, N is the first byte
          of one of them.  The list is sorted by dimensions of the
-         charsets.  A charset of smaller dimension comes firtst.
-      */
+         charsets.  A charset of smaller dimension comes firtst. */
+      Lisp_Object list;
+      int maybe_ascii_compatible = 1;
+
       for (list = Qnil, tail = charset_list; CONSP (tail); tail = XCDR (tail))
         {
           struct charset *charset = CHARSET_FROM_ID (XFASTINT (XCAR (tail)));
@@ -8130,6 +8131,7 @@ usage: (define-coding-system-internal ...)  */)
               val = CHARSET_SUPERSET (charset);
               for (; CONSP (val); val = XCDR (val))
                 list = Fcons (XCAR (XCAR (val)), list);
+              maybe_ascii_compatible = 0;
             }
           else
             list = Fcons (XCAR (tail), list);
@@ -8143,7 +8145,8 @@ usage: (define-coding-system-internal ...)  */)
           int dim = CHARSET_DIMENSION (charset);
           int idx = (dim - 1) * 4;
 
-          if (CHARSET_ASCII_COMPATIBLE_P (charset))
+          if (CHARSET_ASCII_COMPATIBLE_P (charset)
+              && maybe_ascii_compatible)
             CODING_ATTR_ASCII_COMPAT (attrs) = Qt;
 
           for (i = charset->code_space[idx];