https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117204
Dimitry Andric <dimitry at andric dot com> changed:
What |Removed |Added
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CC| |dimitry at andric dot com
--- Comment #4 from Dimitry Andric <dimitry at andric dot com> ---
(In reply to Jeffrey A. Law from comment #3)
> I think the minimized test is bogus. Note:
>
> struct vector : _Vector_base<_Tp, _Alloc> {
> typedef _Vector_base<_Tp, _Alloc> _Base;
> typedef _Base::pointer iterator;
> using _Base::_M_impl;
> vector();
> vector(vector &) { _M_impl._M_finish = 0; }
> __alloc_traits<typename _Base::_Tp_alloc_type>::reference back() {
> iterator __trans_tmp_5 = _M_impl._M_finish, __trans_tmp_2 =
> __trans_tmp_5;
> return *(__trans_tmp_2 - 1);
> }
> };
>
> Note the assignment to _M_impl._M_finish, which is then assigned to
> __trans_tmp_5 which is then assigned to __trans_tmp_2 and then dereferenced.
>
> That corresponds to this chunk of IL:
>
> last = MEM[(const struct tdr_t &)0B + 18446744073709551592];
>
>
> That's going to trigger the out of bounds access warning, but I think it's
> warranted in this case.
It could be that cvise messed this up while reducing, but the basic code came
straight out of libstdc++. So it's still a possible issue in libstdc++.
In any case, we're ignoring -Warray-bounds now since it gives too many false
positives.
