[Bug c/34326] New: pointer arithmetic on void pointers does not generate an error

[Bug c/34326] New: pointer arithmetic on void pointers does not generate an error

[jmparker at marvell dot com]

I was surprised that gcc did not find an error in the following example.
My understanding is that assignment to a void pointer is ok, but arithmetic
is _not_ ok. I have tried this code on my arm cross compiler gcc v. 4.1.1 and
my ubuntu system compiler 4.1.3. Gcc treats the void pointer type as char 

gcc --version
        gcc (GCC) 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2)

Example pointer arithmetic on a void pointer that should have caused an error
   #include <stdlib.h>
   int main (int argc, char **argv)
   {
      void *x;
      x = malloc(1025 * sizeof(*x));

      x++;    // i expected an error on this line!

      return 1;
   }


-- 
           Summary: pointer arithmetic on void pointers does not generate an
                    error
           Product: gcc
           Version: 4.1.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jmparker at marvell dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34326

[Bug c/34326] pointer arithmetic on void pointers does not generate an error

[jmparker at marvell dot com]

------- Comment #1 from jmparker at marvell dot com  2007-12-03 16:03 -------
Created an attachment (id=14694)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=14694&action=view)
simple .c example


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34326

[Bug c/34326] pointer arithmetic on void pointers does not generate an error

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2007-12-03 16:24 -------
This is a GCC extension.  Use -pedantic to get a warning, -pedantic-errors to
get an error.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34326

[Bug c/34326] pointer arithmetic on void pointers does not generate an error

[brian at dessent dot net]

------- Comment #3 from brian at dessent dot net  2007-12-03 16:25 -------
Subject: Re:   New: pointer arithmetic on void pointers does not 
 generate an error

This is a GNU C extension, see
<http://gcc.gnu.org/onlinedocs/gcc/Pointer-Arith.html>.  I think you can
disable it with -std=c89 or -std=c99.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34326