c-common.c

gcc库的原代码,对编程有很大帮助.

     no work for us to do; prototype checking will catch the problem.  */
  for (arg_num = 1; ; ++arg_num)
    {
      if (params == 0)
	return;
      if (arg_num == info->format_num)
	break;
      params = TREE_CHAIN (params);
    }
  format_tree = TREE_VALUE (params);
  params = TREE_CHAIN (params);
  if (format_tree == 0)
    return;
  /* We can only check the format if it's a string constant.  */
  while (TREE_CODE (format_tree) == NOP_EXPR)
    format_tree = TREE_OPERAND (format_tree, 0); /* strip coercion */
  if (integer_zerop (format_tree))
    {
      warning ("null format string");
      return;
    }
  if (TREE_CODE (format_tree) != ADDR_EXPR)
    return;
  format_tree = TREE_OPERAND (format_tree, 0);
  if (TREE_CODE (format_tree) != STRING_CST)
    return;
  format_chars = TREE_STRING_POINTER (format_tree);
  format_length = TREE_STRING_LENGTH (format_tree);
  if (format_length <= 1)
    warning ("zero-length format string");
  if (format_chars[--format_length] != 0)
    {
      warning ("unterminated format string");
      return;
    }
  /* Skip to first argument to check.  */
  while (arg_num + 1 < info->first_arg_num)
    {
      if (params == 0)
	return;
      params = TREE_CHAIN (params);
      ++arg_num;
    }

  first_fillin_param = params;
  while (1)
    {
      int aflag;
      if (*format_chars == 0)
	{
	  if (format_chars - TREE_STRING_POINTER (format_tree) != format_length)
	    warning ("embedded `\\0' in format");
	  if (info->first_arg_num != 0 && params != 0 && ! has_operand_number)
	    warning ("too many arguments for format");
	  return;
	}
      if (*format_chars++ != '%')
	continue;
      if (*format_chars == 0)
	{
	  warning ("spurious trailing `%%' in format");
	  continue;
	}
      if (*format_chars == '%')
	{
	  ++format_chars;
	  continue;
	}
      flag_chars[0] = 0;
      suppressed = wide = precise = FALSE;
      if (info->is_scan)
	{
	  suppressed = *format_chars == '*';
	  if (suppressed)
	    ++format_chars;
	  while (isdigit (*format_chars))
	    ++format_chars;
	}
      else
	{
	  /* See if we have a number followed by a dollar sign.  If we do,
	     it is an operand number, so set PARAMS to that operand.  */
	  if (*format_chars >= '0' && *format_chars <= '9')
	    {
	      char *p = format_chars;

	      while (*p >= '0' && *p++ <= '9')
		;

	      if (*p == '$')
		{
		  int opnum = atoi (format_chars);

		  params = first_fillin_param;
		  format_chars = p + 1;
		  has_operand_number = 1;

		  for (i = 1; i < opnum && params != 0; i++)
		    params = TREE_CHAIN (params);

		  if (opnum == 0 || params == 0)
		    {
		      warning ("operand number out of range in format");
		      return;
		    }
		}
	    }

	  while (*format_chars != 0 && index (" +#0-", *format_chars) != 0)
	    {
	      if (index (flag_chars, *format_chars) != 0)
		{
		  sprintf (message, "repeated `%c' flag in format",
			   *format_chars);
		  warning (message);
		}
	      i = strlen (flag_chars);
	      flag_chars[i++] = *format_chars++;
	      flag_chars[i] = 0;
	    }
	  /* "If the space and + flags both appear, 
	     the space flag will be ignored."  */
	  if (index (flag_chars, ' ') != 0
	      && index (flag_chars, '+') != 0)
	    warning ("use of both ` ' and `+' flags in format");
	  /* "If the 0 and - flags both appear,
	     the 0 flag will be ignored."  */
	  if (index (flag_chars, '0') != 0
	      && index (flag_chars, '-') != 0)
	    warning ("use of both `0' and `-' flags in format");
	  if (*format_chars == '*')
	    {
	      wide = TRUE;
	      /* "...a field width...may be indicated by an asterisk.
		 In this case, an int argument supplies the field width..."  */
	      ++format_chars;
	      if (params == 0)
		{
		  warning (tfaff);
		  return;
		}
	      if (info->first_arg_num != 0)
		{
		  cur_param = TREE_VALUE (params);
		  params = TREE_CHAIN (params);
		  ++arg_num;
		  /* size_t is generally not valid here.
		     It will work on most machines, because size_t and int
		     have the same mode.  But might as well warn anyway,
		     since it will fail on other machines.  */
		  if ((TYPE_MAIN_VARIANT (TREE_TYPE (cur_param))
		       != integer_type_node)
		      &&
		      (TYPE_MAIN_VARIANT (TREE_TYPE (cur_param))
		       != unsigned_type_node))
		    {
		      sprintf (message,
			       "field width is not type int (arg %d)",
			       arg_num);
		      warning (message);
		    }
		}
	    }
	  else
	    {
	      while (isdigit (*format_chars))
		{
		  wide = TRUE;
		  ++format_chars;
		}
	    }
	  if (*format_chars == '.')
	    {
	      precise = TRUE;
	      ++format_chars;
	      if (*format_chars != '*' && !isdigit (*format_chars))
		warning ("`.' not followed by `*' or digit in format");
	      /* "...a...precision...may be indicated by an asterisk.
		 In this case, an int argument supplies the...precision."  */
	      if (*format_chars == '*')
		{
		  if (info->first_arg_num != 0)
		    {
		      ++format_chars;
		      if (params == 0)
		        {
			  warning (tfaff);
			  return;
			}
		      cur_param = TREE_VALUE (params);
		      params = TREE_CHAIN (params);
		      ++arg_num;
		      if (TYPE_MAIN_VARIANT (TREE_TYPE (cur_param))
			  != integer_type_node)
		        {
		          sprintf (message,
				   "field width is not type int (arg %d)",
				   arg_num);
		          warning (message);
		        }
		    }
		}
	      else
		{
		  while (isdigit (*format_chars))
		    ++format_chars;
		}
	    }
	}
      if (*format_chars == 'h' || *format_chars == 'l' || *format_chars == 'q' ||
	  *format_chars == 'L')
	length_char = *format_chars++;
      else
	length_char = 0;
      if (length_char == 'l' && *format_chars == 'l')
	length_char = 'q', format_chars++;
      aflag = 0;
      if (*format_chars == 'a')
	{
	  aflag = 1;
	  format_chars++;
	}
      if (suppressed && length_char != 0)
	{
	  sprintf (message,
		   "use of `*' and `%c' together in format",
		   length_char);
	  warning (message);
	}
      format_char = *format_chars;
      if (format_char == 0)
	{
	  warning ("conversion lacks type at end of format");
	  continue;
	}
      format_chars++;
      fci = info->is_scan ? scan_char_table : print_char_table;
      while (fci->format_chars != 0
	     && index (fci->format_chars, format_char) == 0)
	  ++fci;
      if (fci->format_chars == 0)
	{
	  if (format_char >= 040 && format_char < 0177)
	    sprintf (message,
		     "unknown conversion type character `%c' in format",
		     format_char);
	  else
	    sprintf (message,
		     "unknown conversion type character 0x%x in format",
		     format_char);
	  warning (message);
	  continue;
	}
      if (wide && index (fci->flag_chars, 'w') == 0)
	{
	  sprintf (message, "width used with `%c' format",
		   format_char);
	  warning (message);
	}
      if (precise && index (fci->flag_chars, 'p') == 0)
	{
	  sprintf (message, "precision used with `%c' format",
		   format_char);
	  warning (message);
	}
      if (aflag && index (fci->flag_chars, 'a') == 0)
	{
	  sprintf (message, "`a' flag used with `%c' format",
		   format_char);
	  warning (message);
	}
      if (info->is_scan && format_char == '[')
	{
	  /* Skip over scan set, in case it happens to have '%' in it.  */
	  if (*format_chars == '^')
	    ++format_chars;
	  /* Find closing bracket; if one is hit immediately, then
	     it's part of the scan set rather than a terminator.  */
	  if (*format_chars == ']')
	    ++format_chars;
	  while (*format_chars && *format_chars != ']')
	    ++format_chars;
	  if (*format_chars != ']')
	      /* The end of the format string was reached.  */
	      warning ("no closing `]' for `%%[' format");
	}
      if (suppressed)
	{
	  if (index (fci->flag_chars, '*') == 0)
	    {
	      sprintf (message,
		       "suppression of `%c' conversion in format",
		       format_char);
	      warning (message);
	    }
	  continue;
	}
      for (i = 0; flag_chars[i] != 0; ++i)
	{
	  if (index (fci->flag_chars, flag_chars[i]) == 0)
	    {
	      sprintf (message, "flag `%c' used with type `%c'",
		       flag_chars[i], format_char);
	      warning (message);
	    }
	}
      if (precise && index (flag_chars, '0') != 0
	  && (format_char == 'd' || format_char == 'i'
	      || format_char == 'o' || format_char == 'u'
	      || format_char == 'x' || format_char == 'x'))
	{
	  sprintf (message,
		   "precision and `0' flag not both allowed with `%c' format",
		   format_char);
	  warning (message);
	}
      switch (length_char)
	{
	default: wanted_type = fci->nolen ? *(fci->nolen) : 0; break;
	case 'h': wanted_type = fci->hlen ? *(fci->hlen) : 0; break;
	case 'l': wanted_type = fci->llen ? *(fci->llen) : 0; break;
	case 'q': wanted_type = fci->qlen ? *(fci->qlen) : 0; break;
	case 'L': wanted_type = fci->bigllen ? *(fci->bigllen) : 0; break;
	}
      if (wanted_type == 0)
	{
	  sprintf (message,
		   "use of `%c' length character with `%c' type character",
		   length_char, format_char);
	  warning (message);
	}

      /*
       ** XXX -- should kvetch about stuff such as
       **	{
       **		const int	i;
       **
       **		scanf ("%d", &i);
       **	}
       */

      /* Finally. . .check type of argument against desired type!  */
      if (info->first_arg_num == 0)
	continue;
      if (fci->pointer_count == 0 && wanted_type == void_type_node)
	/* This specifier takes no argument.  */
	continue;
      if (params == 0)
	{
	  warning (tfaff);
	  return;
	}
      cur_param = TREE_VALUE (params);
      params = TREE_CHAIN (params);
      ++arg_num;
      cur_type = TREE_TYPE (cur_param);

      /* Check the types of any additional pointer arguments
	 that precede the "real" argument.  */
      for (i = 0; i < fci->pointer_count; ++i)
	{
	  if (TREE_CODE (cur_type) == POINTER_TYPE)
	    {
	      cur_type = TREE_TYPE (cur_type);
	      continue;
	    }
	  if (TREE_CODE (cur_type) != ERROR_MARK)
	    {
	      sprintf (message,
		       "format argument is not a %s (arg %d)",
		       ((fci->pointer_count == 1) ? "pointer" : "pointer to a pointer"),
		       arg_num);
	      warning (message);
	    }
	  break;
	}

      /* Check the type of the "real" argument, if there's a type we want.  */
      if (i == fci->pointer_count && wanted_type != 0
	  && TREE_CODE (cur_type) != ERROR_MARK
	  && wanted_type != TYPE_MAIN_VARIANT (cur_type)
	  /* If we want `void *', allow any pointer type.
	     (Anything else would already have got a warning.)  */
	  && ! (wanted_type == void_type_node
		&& fci->pointer_count > 0)
	  /* Don't warn about differences merely in signedness.  */
	  && !(TREE_CODE (wanted_type) == INTEGER_TYPE
	       && TREE_CODE (TYPE_MAIN_VARIANT (cur_type)) == INTEGER_TYPE
	       && (TREE_UNSIGNED (wanted_type)
		   ? wanted_type == (cur_type = unsigned_type (cur_type))
		   : wanted_type == (cur_type = signed_type (cur_type))))
	  /* Likewise, "signed char", "unsigned char" and "char" are
	     equivalent but the above test won't consider them equivalent.  */
	  && ! (wanted_type == char_type_node
		&& (TYPE_MAIN_VARIANT (cur_type) == signed_char_type_node
		    || TYPE_MAIN_VARIANT (cur_type) == unsigned_char_type_node)))
	{
	  register char *this;
	  register char *that;
  
	  this = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (wanted_type)));
	  that = 0;
	  if (TREE_CODE (cur_type) != ERROR_MARK
	      && TYPE_NAME (cur_type) != 0
	      && TREE_CODE (cur_type) != INTEGER_TYPE
	      && !(TREE_CODE (cur_type) == POINTER_TYPE
		   && TREE_CODE (TREE_TYPE (cur_type)) == INTEGER_TYPE))
	    {
	      if (TREE_CODE (TYPE_NAME (cur_type)) == TYPE_DECL
		  && DECL_NAME (TYPE_NAME (cur_type)) != 0)
		that = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (cur_type)));
	      else
		that = IDENTIFIER_POINTER (TYPE_NAME (cur_type));
	    }

	  /* A nameless type can't possibly match what the format wants.
	     So there will be a warning for it.
	     Make up a string to describe vaguely what it is.  */
	  if (that == 0)
	    {
	      if (TREE_CODE (cur_type) == POINTER_TYPE)
		that = "pointer";
	      else
		that = "different type";
	    }

	  /* Make the warning better in case of mismatch of int vs long.  */
	  if (TREE_CODE (cur_type) == INTEGER_TYPE
	      && TREE_CODE (wanted_type) == INTEGER_TYPE
	      && TYPE_PRECISION (cur_type) == TYPE_PRECISION (wanted_type)