https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93848
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |NEW
CC| |msebor at gcc dot gnu.org
Component|c |middle-end
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=93514
Blocks| |56456
Severity|normal |enhancement
--- Comment #5 from Martin Sebor <msebor at gcc dot gnu.org> ---
The warning is emitted for the original test case once it's made clear that
bar_aux dereferences the pointer using the access attribute:
__attribute__ ((access (read_write, 1))) void bar_aux (int *);
But in the absence of any evidence that the past-the-end pointer is
dereferenced, it can't, in general, be diagnosed without causing false
positives such as in calls to functions that take two pointers of compatible
types:
void baz_aux (int *, int *);
The function could be called on a range:
int a[3];
baz_aux (a, a + 3);
as often happens in C++ (many functions in the standard library take two
iterators delineating a range as arguments, and are often called just like the
one above).
But I do think issuing a warning for a subset of these cases would be safe and
helpful. For instance, when passing a past-the-end pointer to a function that
takes just a single pointer would be okay because the function in all
likelihood does dereference it. I recently opened bug 93514 noting this problem
in calls to built-ins (pr93514). There, the past-the-end pointer is certain to
be accessed by the function, but the warning doesn't have the logic to detect
it.
Anyway, let me confirm this report as an enhancement request for a warning
along the lines of the idea in bug 93514 comment 1.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56456
[Bug 56456] [meta-bug] bogus/missing -Warray-bounds
