Re: _LIBCXX_DEBUG value initialized singular iterators assert failures in std algorithms [PR104316]

[Jonathan Wakely <jwakely@redhat.com>]

On Sun, 17 Mar 2024 at 18:14, François Dumont <frs.dumont@gmail.com> wrote:
>
> I was a little bit too confident below. After review of all _M_singular
> usages I found another necessary fix.
>
> After this one for sure we will be able to define
> __cpp_lib_null_iterators even in Debug mode.
>
>      libstdc++: Fix N3344 behavior on _Safe_iterator::_M_can_advance
>
>      We shall be able to advance from a 0 offset a value-initialized
> iterator.
>
>      libstdc++-v3/ChangeLog:
>
>              * include/debug/safe_iterator.tcc
> (_Safe_iterator<>::_M_can_advance):
>              Accept 0 offset advance on value-initialized iterator.
>              * testsuite/23_containers/vector/debug/n3644.cc: New test case.
>
> Ok to commit ?


OK, thanks.


> François
>
>
> On 17/03/2024 17:52, François Dumont wrote:
> >
> >>
> >> OK for trunk, thanks!
> >>
> >> I think this is OK to backport to 13 too.
> >>
> >> Maybe after this we can define the __cpp_lib_null_itetators macro for
> >> debug mode?
> >>
> > After this fix of local_iterator I think we can indeed.
> >
> > In fact the added 11316.cc was already passing for
> > unordered_set<>::local_iterator but simply because we were missing the
> > singular check. Both issues solved with this patch.
> >
> > I found the version.def file to cleanup but no idea how to regenerate
> > version.h from it so I'll let you do it, ok ?
> >
> >     libstdc++: Fix _Safe_local_iterator<>::_M_valid_range
> >
> >     Unordered container local_iterator range shall not contain any
> > singular
> >     iterator unless both iterators are value-initialized.
> >
> >     libstdc++-v3/ChangeLog:
> >
> >             * include/debug/safe_local_iterator.tcc
> >             (_Safe_local_iterator::_M_valid_range): Add
> > _M_value_initialized and
> >             _M_singular checks.
> >             * testsuite/23_containers/unordered_set/debug/114316.cc:
> > New test case.
> >
> >
> > Ok to commit ?
> >
> > François