(Fset_terminal_coding_system_internal): Set

CODING_FLAG_ISO_SAFE in terminal_coding.flags.
(ENCODE_ISO_CHARACTER_DIMENSION1): Check
CODING_SPEC_ISO_EXPECTED_CHARSETS.
(ENCODE_ISO_CHARACTER_DIMENSION2): Likewise.

src/coding.c

@@ -1204,8 +1204,7 @@ decode_coding_iso2022 (coding, source, destination,
 	break;								\
       }									\
     else if (coding->flags & CODING_FLAG_ISO_SAFE			\
-	     && (CODING_SPEC_ISO_REQUESTED_DESIGNATION (coding, charset) \
-		 == CODING_SPEC_ISO_NO_REQUESTED_DESIGNATION))		 \
+	     && !CODING_SPEC_ISO_EXPECTED_CHARSETS (coding)[charset])	\
       {									\
 	/* We should not encode this character, instead produce one or	\
 	   two `?'s.  */						\
@@ -1248,8 +1247,7 @@ decode_coding_iso2022 (coding, source, destination,
 	break;								\
       }									\
     else if (coding->flags & CODING_FLAG_ISO_SAFE			\
-	     && (CODING_SPEC_ISO_REQUESTED_DESIGNATION (coding, charset) \
-		 == CODING_SPEC_ISO_NO_REQUESTED_DESIGNATION))		 \
+	     && !CODING_SPEC_ISO_EXPECTED_CHARSETS (coding)[charset])	\
       {									\
 	/* We should not encode this character, instead produce one or	\
 	   two `?'s.  */						\
@@ -2380,9 +2378,9 @@ setup_coding_system (coding_system, coding)
 	CODING_SPEC_ISO_INVOCATION (coding, 1)
 	  = (coding->flags & CODING_FLAG_ISO_SEVEN_BITS ? -1 : 1);
 	/* Not single shifting at first.  */
-	CODING_SPEC_ISO_SINGLE_SHIFTING(coding) = 0;
+	CODING_SPEC_ISO_SINGLE_SHIFTING (coding) = 0;
 	/* Beginning of buffer should also be regarded as bol. */
-	CODING_SPEC_ISO_BOL(coding) = 1;
+	CODING_SPEC_ISO_BOL (coding) = 1;
 
 	/* Checks FLAGS[REG] (REG = 0, 1, 2 3) and decide designations.
 	   FLAGS[REG] can be one of below:
@@ -2397,6 +2395,7 @@ setup_coding_system (coding_system, coding)
 	for (charset = 0; charset <= MAX_CHARSET; charset++)
 	  CODING_SPEC_ISO_REQUESTED_DESIGNATION (coding, charset)
 	    = CODING_SPEC_ISO_NO_REQUESTED_DESIGNATION;
+	bzero (CODING_SPEC_ISO_EXPECTED_CHARSETS (coding), MAX_CHARSET + 1);
 	for (i = 0; i < 4; i++)
 	  {
 	    if (INTEGERP (flags[i])
@@ -2405,6 +2404,7 @@ setup_coding_system (coding_system, coding)
 	      {
 		CODING_SPEC_ISO_INITIAL_DESIGNATION (coding, i) = charset;
 		CODING_SPEC_ISO_REQUESTED_DESIGNATION (coding, charset) = i;
+		CODING_SPEC_ISO_EXPECTED_CHARSETS (coding)[charset] = 1;
 	      }
 	    else if (EQ (flags[i], Qt))
 	      {
@@ -2422,6 +2422,7 @@ setup_coding_system (coding_system, coding)
 		  {
 		    CODING_SPEC_ISO_INITIAL_DESIGNATION (coding, i) = charset;
 		    CODING_SPEC_ISO_REQUESTED_DESIGNATION (coding, charset) =i;
+		    CODING_SPEC_ISO_EXPECTED_CHARSETS (coding)[charset] = 1;
 		  }
 		else
 		  CODING_SPEC_ISO_INITIAL_DESIGNATION (coding, i) = -1;
@@ -2432,8 +2433,12 @@ setup_coding_system (coding_system, coding)
 			&& (charset = XINT (XCONS (tail)->car),
 			    CHARSET_VALID_P (charset))
 			|| (charset = get_charset_id (XCONS (tail)->car)) >= 0)
+		      {
 			CODING_SPEC_ISO_REQUESTED_DESIGNATION (coding, charset)
 			  = i;
+			CODING_SPEC_ISO_EXPECTED_CHARSETS (coding)[charset]
+			  = 1;
+		      }
 		    else if (EQ (XCONS (tail)->car, Qt))
 		      default_reg_bits |= 1 << i;
 		    tail = XCONS (tail)->cdr;
@@ -2456,7 +2461,6 @@ setup_coding_system (coding_system, coding)
 	      default_reg_bits &= 3;
 	  }
 
-	if (! (coding->flags & CODING_FLAG_ISO_SAFE))
 	for (charset = 0; charset <= MAX_CHARSET; charset++)
 	  if (CHARSET_VALID_P (charset)
 	      && (CODING_SPEC_ISO_REQUESTED_DESIGNATION (coding, charset)
@@ -3585,6 +3589,9 @@ DEFUN ("set-terminal-coding-system-internal",
 {
   CHECK_SYMBOL (coding_system, 0);
   setup_coding_system (Fcheck_coding_system (coding_system), &terminal_coding);
+  /* We had better not send unexpected characters to terminal.  */
+  terminal_coding.flags |= CODING_FLAG_ISO_SAFE;
+
   return Qnil;
 }