[Bug middle-end/92378] missing -Warray-bounds warning

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92378

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |msebor at gcc dot gnu.org
          Component|c                           |middle-end
         Resolution|---                         |DUPLICATE
           Assignee|unassigned at gcc dot gnu.org      |msebor at gcc dot gnu.org
   Target Milestone|---                         |10.0

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
The cause of the missing -Warray-bounds warning is that the SRA pass
substitutes an uninitialized scalar variable for a[3].  I'm not sure why
-Wuninitialized doesn't point to the variable, but the fix for pr92341 I'm
about to commit corrects this as well and has GCC output the following:

pr92378.c: In function ‘main’:
pr92378.c:5:5: warning: array subscript 3 is above array bounds of ‘int[1]’
[-Warray-bounds]
    5 |     printf("%d", a[3]);
      |     ^~~~~~~~~~~~~~~~~~
pr92378.c:4:9: note: while referencing ‘a’
    4 |     int a[1]={0};
      |         ^


In GCC, -Warray-bounds only runs with optimization so the bug isn't detected
otherwise even in simple cases.  In a future release (maybe GCC 11) we'd like
to change it so the simple cases can be diagnosed even without optimization.

*** This bug has been marked as a duplicate of bug 92341 ***