https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103292
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|INVALID |DUPLICATE
Component|c |middle-end
Blocks| |56456
CC| |jeffreyalaw at gmail dot com
--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
The originally intended purpose of this instance of -Warray-bounds was to warn
for accesses to smaller buffers by larger lvalues, like in this function:
struct A { int i; };
struct B { long j; };
struct B* make_B_from_A (const struct A *p)
{
struct B *q = __builtin_malloc (sizeof *p); // should be sizeof *q
q->j = p->i;
return q;
}
Here a warning should be issued regardless of whether -fstrict-aliasing is in
effect because the access is out of bounds. That the warning also triggers in
instances when the problem isn't one of an out-of-bounds access but rather an
aliasing violation was incidental (i.e., I didn't set out with that as a goal),
but because -Wstrict-aliasing in GCC is very limited, seemed like a bonus.
So an argument could be (and in pr98503 in fact was) made that the instances of
-Warray-bounds where the ultimate access is strictly in bounds should be
replaced by one of -Wstrict-aliasing, which is enabled only when
-fstrict-aliasing is in effect. I agreed and submitted a patch to do that:
https://gcc.gnu.org/pipermail/gcc-patches/2021-January/564483.html
Regrettably, the change was rejected. I CC the reviewer for his comments.
*** This bug has been marked as a duplicate of bug 98503 ***
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56456
[Bug 56456] [meta-bug] bogus/missing -Warray-bounds
