[Bug middle-end/68270] [MPX] Common pattern for variable sized data clashes with MPX bound checks

["marxin at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68270

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2017-03-03
                 CC|                            |marxin at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |marxin at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #4 from Martin Liška <marxin at gcc dot gnu.org> ---
The issue is not solved, let's consider:

$ cat /tmp/chkp.ii
typedef struct a *b;
struct a {
  struct {
    int e[1];
  } f;
};
int g(b ptr)
{
  return ptr->f.e[1];
}

$ ./xgcc -B. /tmp/chkp.ii -Werror -c -mmpx -fcheck-pointer-bounds -O1 -Wall
-fchkp-flexible-struct-trailing-arrays 
/tmp/chkp.ii: In function ‘int g.chkp(b,
\xe2\x80\x98pointer_bounds_typ\xe2\x80\x99 not supported by dump_type#<type
error>, void, ...)’:
/tmp/chkp.ii:9:20: error: memory access check always fail [-Werror=chkp]
   return ptr->f.e[1];
                    ^
cc1plus: all warnings being treated as errors

It's wrong and reason is explained in Richi's email:
https://gcc.gnu.org/ml/gcc-patches/2017-01/msg00172.html

I'm testing the patch.