Re: c/4967: GCC should warn about obvious violations of restrict

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

The following reply was made to PR c/4967; it has been noted by GNATS.

From: "Joseph S. Myers" <jsm28@cam.ac.uk>
To: Andreas Jaeger <aj@suse.de>
Cc: <gcc-gnats@gcc.gnu.org>,  <ma@suse.de>,  <gcc-bugs@gcc.gnu.org>
Subject: Re: c/4967: GCC should warn about obvious violations of restrict
Date: Thu, 29 Nov 2001 12:40:56 +0000 (GMT)

 On Thu, 29 Nov 2001, Andreas Jaeger wrote:
 
 > The compiler should use the restrict keyword of ISO C99 when invoking
 > functions and check that the aliasing rules are not violated on the
 > call side.
 
 Why?  The keyword provides no information whatsoever to the call side,
 since the function needn't access the objects pointed to by its arguments
 at all.
 
 > Compile this program - it should give a warning:
 > int
 > sprintf_restrict (char *restrict s, const char *restrict t)
 > {
 >   return *s!=*t;
 > }
 > 
 > 
 > 
 > int main (void)
 > {
 >   char buf[64];
 > 
 >   sprintf_restrict (buf, buf);
 > 
 >   return 0;
 > }
 
 The program is perfectly valid; while sprintf_restrict could have a const
 on the target type of its first parameter, there's no need for it to have
 one.
 
 -- 
 Joseph S. Myers
 jsm28@cam.ac.uk