Re: warning for -Wformat and non-literal-string format

[Andreas Jaeger <aj at suse dot de>]

>>>>> Jeffrey A Law writes:

>> ------- Start of forwarded message -------
>> Message-Id: <199910070051.UAA12759@dcl.mit.edu>
>> From: Ken Raeburn <raeburn@MIT.EDU>
>> To: gcc-patches@egcs.cygnus.com
>> 
>> I ran into some problems with code that did lame-o stuff like this:
>> 
>> vsprintf (buf, fmt, ap);
>> ...
>> fprintf (logfile, buf);
>> 
>> when one of the supplied strings included a %s or %n that wound up in
>> "buf".  The following patch is helping me track down such bugs.
>> 
>> Unfortunately, it also complains on variadic routines that themselves
>> accept formats and parameters, and call vfprintf or vsyslog or
>> whatever.  If such calling functions have format attribute
>> declarations too, it may be possible to refine the check somewhat.
>> But I'm just going to check those cases by hand, for now. :-)
>> 
>> That might be a good reason to use a different -W flag for now.  (Yet
>> another one??)  Let me know if you want another patch to do it that
>> way.
>> 
>> Ken
>> 
>> 
>> Wed Oct  6 01:59:29 1999  Ken Raeburn  <raeburn@mit.edu>
>> 
>> * c-common.c (check_format_info): Warn if format string isn't a
>> string literal.
Jeff> Thanks.  Installed.

Jeff> Note I removed the goto usage and just copied the warning/return statements.

Jeff> Depending on how often it triggers we may or may not have to make it a 
Jeff> separate option.  I consider that issue unresolved at this time.

Bootstrapping egcs I got a number of:
In file included from /usr/include/stdio.h:631,
                 from ../../cvs/gcc/gcc/system.h:33,
                 from insn-emit.c:5:
/usr/include/bits/stdio.h: In function `vprintf':
/usr/include/bits/stdio.h:35: warning: format not a string literal, argument types not checked

The warnings come from this piece of code in <bits/stdio.h> (from
glibc 2.1.2):

/* Write formatted output to stdout from argument list ARG.  */
__STDIO_INLINE int
vprintf (__const char *__restrict __fmt, _G_va_list __arg) __THROW
{
  return vfprintf (stdout, __fmt, __arg);
}

Is there a way to stop these warnings?

Andreas
-- 
 Andreas Jaeger   
  SuSE Labs aj@suse.de	
   private aj@arthur.rhein-neckar.de