On Mon, 9 Dec 2024, 06:05 François Dumont, <frs.dum...@gmail.com> wrote:
>
> On 04/12/2024 22:48, Jonathan Wakely wrote:
> > On 04/12/24 19:27 +0100, François Dumont wrote:
> >> Hi
> >>
> >> I've completed the synchronization with your equivalent PR for
> >> std::list so here is the updated patch.
> >>
> >> PR updated a couple of days ago.
> >>
> >> Note that I've started to rework the patch for the same in _Hashtable.
> >
> > Great, thanks.
> >
> >>
> >> #if __cplusplus < 201103L
> >> void
> >> - _M_construct_node(_Link_type __node, const value_type& __x)
> >> + _M_construct_node(_Base_ptr __p, const value_type& __x)
> >
> > And can this be left as _Node_ptr instead of changed to _Base_ptr?
> > Then it wouldn't need the static_cast, and the callers wouldn't need
> > to use _M_base_ptr().
> >
> > Logically, it has to be a _Node_ptr or the cast isn't valid anyway.
> >
> > There seem to be several places like this where we're giving up
> > valuable type information by using _base_ptr instead of _Node_ptr.
> >
> > Is that really necessary? If we have a _Node_ptr we can always get a
> > _Base_ptr easily by calling _M_base_ptr().
> >
> > Is it a constness thing, because _M_begin() const was changed to
> > return _Base_ptr instead of _Const_link_ptr?
> >
> No, just me being lazy and considering that as we store _Base_ptr we can
> also use it everywhere.
>
> In this new version I've preserved _Node_ptr almost everywhere.
>
> But _M_begin() is still returning a _Base_ptr and I've introduced
> _M_begin_node() for rare occasions when a _Node_ptr is needed.
>
> Note that I've hesitated to add a _S_nullptr() to get a _Base_ptr null
> pointer. Is default constructor on fancy pointer type mandatory ?
Yes, but default construction can give a singular value (like an
uninitialized int*) so you want to use value initialization.
So:
pointer p = pointer();
Or in C++11:
pointer p{};
And not just:
pointer p;
I fear
> that only constructor from nullptr is mandatory.
>
Value init is required to work by the Cpp17NullablePointer requirements.
> I've forced push on:
>
> https://forge.sourceware.org/gcc/gcc-TEST/pulls/27
Thanks, I'll take another look.
