GCC char* bug

[Bruce Korb <bkorb at pacbell dot net>]

When the input character is 0xF5 and char is signed,
the following code fails to compare equal:

        1257	static void test_for_changes PARAMS ((int));
 	1258	static void
 	1259	test_for_changes (read_fd)
 	1260	  int read_fd;
-	1261	{
-	1262	  FILE *in_fp = fdopen (read_fd, "r");
-	1263	  FILE *out_fp = (FILE *) NULL;
-	1264	  char *pz_cmp = pz_curr_data;
 	1265	

unsigned char *pz_cmp = (unsigned char*)pz_curr_data;

 	1266	#ifdef DO_STATS
 	1267	  fixed_ct++;
 	1268	#endif
-	1269	  for (;;)
 	1270	    {
-	1271	      int ch;
 	1272	
-	1273	      ch = getc (in_fp);
-	1274	      if (ch == EOF)
-	1275	        break;
 	1276	

ch &= 0xFF; /* bytes will only ever be 8 bits */

 	1277	      /*  IF we are emitting the output
 	1278	          THEN emit this character, too.
 	1279	      */
-	1280	      if (out_fp != (FILE *) NULL)
-	1281	        putc (ch, out_fp);
 	1282	
 	1283	      /*  ELSE if this character does not match the original,
 	1284	          THEN now is the time to start the output.
 	1285	      */
-	1286	      else if (ch != *pz_cmp)
 	1287	        {
	1288	          out_fp = create_file ();

Line 1286 compares "ch"(-10) with "*pz_cmp"(246) and says that they are
not equal.  The workaround is obvious, but by golly chars
are either signed or they are not signed.  If they are not
signed, then the compare should show equal.  On the other
hand, if they *are* signed, then 0xF5 should compare equal
to 0xFFFFFFF5.  You cannot just do it one way sometimes
and another way other times.