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Lua fails to parse hexadecimal numbers under IRIX (6.5.30), 
evidently caused by a buggy strtod implementation. strtod just 
doesn't advance the endpointer exactly if s starts with '0x' 
('0y' or '1x' yield the expected result), so that (endptr == s) 
holds and the conversion fails. 

The modified luaO_str2d, the example program and its output
below illustrate the problem and a potential workaround:

int luaO_str2d (const char *s, lua_Number *result) {
  char *endptr;

  *result = lua_str2number(s, &endptr);
  *result = strtod(s, &endptr);
  printf("result %li\n", *result);
  printf("endptr %s\n", endptr);
  if ((*s == '0') &&
      (*(s+1) == 'x' || *(s+1) == 'X'))  /* maybe an hexadecimal constant? */
    printf("hex    %s\n", endptr);
    *result = cast_num(strtoul(s, &endptr, 16));
  if (endptr == s) return 0;  /* conversion failed */
  if (*endptr == '\0') return 1;  /* most common case */
  while (isspace(cast(unsigned char, *endptr))) endptr++;
  if (*endptr != '\0') return 0;  /* invalid trailing characters? */
  return 1;



result 0
endptr 0xff
hex    0xff
result 0
endptr xff
result 0
endptr xff
./lua: ../../hex.lua:2: malformed number near '1xff'