[Bug middle-end/60957] [4.9/4.10 Regression] Bogus error: array subscript is above array bounds [-Werror=array-bounds]

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60957

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
             Status|NEW                         |UNCONFIRMED
     Ever confirmed|1                           |0

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is not fully a bogus warning.  The warning is true if xxx._enabled is
false and bar returns something which is > 8.

Here is a shorter testcase:
extern bool foobar(const unsigned int);
extern void foo (void);
extern void bar2(bool *enabled, unsigned int old_width)
{
  static const unsigned int size_map[] = { 0, 1, 2, 0, 4, 0, 0, 0, 8};
  if(old_width > 8)
    if(*enabled)
      foo ();
  unsigned int size = size_map[old_width];
  if(size == 0)
    if(*enabled)
      foo ();
  if(foobar(size))
    foo ();
}

We are transforming the above into:
extern bool foobar(const unsigned int);
extern void foo (void);
extern void bar2(bool *enabled, unsigned int old_width)
{
  unsigned int size;
  static const unsigned int size_map[] = { 0, 1, 2, 0, 4, 0, 0, 0, 8};
  if(old_width > 8)
  {
    if(*enabled)
      foo ();
    else
      {
        size = size_map[old_width];
        goto t;
      }
  }
  size = size_map[old_width];
  if(size == 0)
    if(*enabled)
      foo ();
t:
  if(foobar(size))
    foo ();
}


Which is correct and we are warning about the access under the else statement.