From: "François Dumont" <frs.dumont@gmail.com>
To: Jonathan Wakely <jwakely@redhat.com>
Cc: libstdc++ <libstdc++@gcc.gnu.org>, gcc-patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] Replace __gnu_cxx::__ops::__negate with std::not_fn
Date: Wed, 24 May 2023 06:51:52 +0200 [thread overview]
Message-ID: <84a7b527-d2b9-c244-8fde-c141cdce23b7@gmail.com> (raw)
In-Reply-To: <CACb0b4n07jjF0dc6wSPkAsN1P0RkiDYyfd=r15yGcsEhiT239w@mail.gmail.com>
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On 22/05/2023 22:55, Jonathan Wakely wrote:
>
>
> On Mon, 22 May 2023 at 21:51, François Dumont via Libstdc++
> <libstdc++@gcc.gnu.org <mailto:libstdc%2B%2B@gcc.gnu.org>> wrote:
>
> I was thinking that it might be nice to get rid of
> predefined_ops.h content.
>
> So here is a start with __negate. Drawback is that stl_algo.h has to
> include <functional>.
>
>
> We definitely don't want that. std::not_fn could be move to its own
> header.
>
> But I'm not sure this is a good change anyway, as we can't do it
> unconditionally. Pre-C++17 code would still be using the
> predefined_ops.h function objects, so we can't remove that code. And
> we'll get template bloat from instantiating the algos twice, once with
> the old function objects and once with std::not_fn.
True, what do you advise then ? Should I just forget about it ?
Introduce a std::__not_fn for pre-C++17 ?
I am studying this last proposal, let me know if it is just impossible
or a waste of time.
>
> For now I just get rid of stl_algo.h include in
> <functional> to rather use stl_algobase.h. But maybe it would be
> better
> to also isolate std::not_fn in a dedicated header file so that
> stl_algo.h do not have to include all <functional>.
>
> libstdc++: Replace __gnu_cxx::__ops::__negate with std::not_fn
>
> Replace the internal __gnu_cxx::__ops::__negate function and
> associated
> __gnu_cxx::__ops::_Iter_negate by the C++17 std::not_fn.
>
> libstdc++-v3/ChangeLog:
>
> * include/bits/predefined_ops.h: Include <version>.
>
>
> No, please don't include <version> anywhere. If you do that, it means
> <functional> now defines every feature test macro in the entire
> library, which makes it look like you can get smart pointers and
> ranges and constexpr math all from <functional>.
Ok, I wasn't aware about the interest of <version>. I see now, limited
to user code.
I'm testing only the move of std::search to stl_algobase.h to avoid
stl_algo.h include in <functional>. I'll submit it later.
prev parent reply other threads:[~2023-05-24 4:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-22 20:50 François Dumont
2023-05-22 20:55 ` Jonathan Wakely
2023-05-24 4:51 ` François Dumont [this message]
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