Re: c/6547: misleading printf '$' format

["Joseph S. Myers" <jsm28@cam.ac.uk>]

The following reply was made to PR c/6547; it has been noted by GNATS.

From: "Joseph S. Myers" <jsm28@cam.ac.uk>
To: Pierre-Canalsat PETIT <pierrecanalsat.petit.canalsat@canal-plus.com>
Cc: <gcc-bugs@gcc.gnu.org>,  <gcc-gnats@gcc.gnu.org>, 
     <gcc-patches@gcc.gnu.org>,  <peio@blutch.dyndns.org>, 
     <prpetit@canal-plus.com>
Subject: Re: c/6547: misleading printf '$' format
Date: Fri, 3 May 2002 21:19:08 +0100 (BST)

 On Fri, 3 May 2002, Pierre-Canalsat PETIT wrote:
 
 > int main(int argc, char *argv[]) {
 >   printf("Usage: %1$s [-n <option 1>] [-m <option 2>]\n"
 >        "       %3$*2$c [-i <input>] [-o <output>] [-c <nb>] [-t <ms>]\n"
 >        "       %3$*2$c <file.in> <file.out>\n", *argv, strlen(*argv), ' ');
 >   return 0;
 > }
 > 
 > This returns me a "warning: too few arguments for format".
 > But if you remove the second line of the format, it does compile
 > without warning...
 
 Thanks for that bug report.  Patch below applied to mainline only
 (since it's not a regression).  Bootstrapped with no regressions on
 i686-pc-linux-gnu.
 
 2002-05-03  Joseph S. Myers  <jsm28@cam.ac.uk>
 
 	* c-format.c (check_format_info_main): Don't check for presence of
 	parameter for * width until after operand number has been read,
 	and only check for it if format parameters are available.
 	Fixes PR c/6547.
 
 testsuite:
 2002-05-03  Joseph S. Myers  <jsm28@cam.ac.uk>
 
 	* gcc.dg/format/xopen-2.c: New test.
 
 --- c-format.c.orig	2002-04-19 19:10:11.000000000 +0000
 +++ c-format.c	2002-05-03 15:01:13.000000000 +0000
 @@ -1751,11 +1751,6 @@ check_format_info_main (status, res, inf
  	      /* "...a field width...may be indicated by an asterisk.
  		 In this case, an int argument supplies the field width..."  */
  	      ++format_chars;
 -	      if (params == 0)
 -		{
 -		  status_warning (status, "too few arguments for format");
 -		  return;
 -		}
  	      if (has_operand_number != 0)
  		{
  		  int opnum;
 @@ -1775,6 +1770,11 @@ check_format_info_main (status, res, inf
  		}
  	      if (info->first_arg_num != 0)
  		{
 +		  if (params == 0)
 +		    {
 +		      status_warning (status, "too few arguments for format");
 +		      return;
 +		    }
  		  cur_param = TREE_VALUE (params);
  		  if (has_operand_number <= 0)
  		    {
 --- testsuite/gcc.dg/format/xopen-2.c	2001-03-26 23:57:02.000000000 +0000
 +++ testsuite/gcc.dg/format/xopen-2.c	2002-05-03 14:59:20.000000000 +0000
 @@ -0,0 +1,21 @@
 +/* Test for X/Open format extensions, as found in the
 +   Single Unix Specification.  Test for bug reported by
 +   Pierre-Canalsat PETIT <pierrecanalsat.petit.canalsat@canal-plus.com>
 +   in PR c/6547.  The test for absence of a parameter for a * width was done
 +   too early in the case of operand numbers and vprintf formats.
 +*/
 +/* Origin: Joseph Myers <jsm28@cam.ac.uk> */
 +/* { dg-do compile } */
 +/* { dg-options "-std=gnu99 -Wformat" } */
 +
 +#include "format.h"
 +
 +void vbar (va_list, const char *) __attribute__((__format__(__printf__, 2, 0)));
 +
 +void
 +foo (int i, int j, va_list va)
 +{
 +  printf("%2$*1$c", i, j);
 +  printf("%2$*1$c %2$*1$c", i, j); /* { dg-bogus "too few" "bogus too few dollar" } */
 +  vbar(va, "%*s"); /* { dg-bogus "too few" "bogus too few vprintf" } */
 +}
 
 -- 
 Joseph S. Myers
 jsm28@cam.ac.uk