From: "Michał Górny" <mgorny@gentoo.org>
To: "Gregory M. Turner" <gmt@be-evil.net>
Cc: gentoo-dev@lists.gentoo.org
Subject: Re: [gentoo-dev] impending c++11 clusterfuck?
Date: Mon, 30 Nov 2015 07:42:35 +0100 [thread overview]
Message-ID: <20151130074235.5a0fec7b.mgorny@gentoo.org> (raw)
In-Reply-To: <4065232.vgWU8t9PnH@moneypit>
[-- Attachment #1: Type: text/plain, Size: 2842 bytes --]
On Sun, 29 Nov 2015 19:56:04 -0800
"Gregory M. Turner" <gmt@be-evil.net> wrote:
> I'm quoting myself from bug #566328 here. These were off-the-cuff
> remarks that got away from me and became a call-to-arms...
>
> (In reply to Michał Górny from comment #7)
> > This is never this simple. C++11 can change the ABI. So the point kinda is,
> > we need to ensure that all C++ libraries in a depgraph use the same C++
> > version.
>
> This is pretty awful when you really think about it. I feel like I'm
> watching a train-wreck in super slow motion.
Well, it's not that bad actually. After some thinking, I figured out
they fixed most 98/11 incompatibilities around gcc 4.8/4.9, and left
only a few 'unlikely' to cause issues.
However, if one dep switches to C++11, it is quite likely to require
C++11 in its revdeps, and that's what happening with libsigc++
and other gtkmm libraries.
Plus, there's of course the classical issue of ABI incompatibility
between libstdc++ bundled with 4.9 and 5.1, and 5.2... so along with
switching g++ version, you soon start to have to rebuild random C++
libraries.
And the issue of supporting alternative C++ standard library
implementations -- like using libcxx with clang. They are of course
incompatible with GNU's ever-changing ABI.
> I'm not sure we're taking this seriously enough -- sooner or later it
> seems destined to become a major clusterfuck if we don't do something
> proactive about it now while the drawing-board is relatively
> uncluttered.
>
> The only thing I can think of that has this kind of two-way depgraph
> magic property are the major "abi" USE_EXPAND values (multilib-build
> and python-r1, in other words).
>
> But those rely on fancy framework-generated USE-flag deps, which seem
> like overkill and likely to incur unjustifiable user-experience-costs.
Yes, it is terrible. You end up introducing a lot of USE flags that
need to be manually switched along with gcc versions. If we start
splitting them between c++98 and c++11, we're quite likely to hit USE
flag conflicts between packages/developers which prefer one over
another.
> Perhaps a solution to this cxx11 clusterfuck can be found that works
> more like perl? By that I mean, pick your poison (respectively, your
> cxx11 ABI of preference or your major perl version of choice), rely on
> inbuilt portage features do the trick most of the time, and, when it
> breaks, run "magically-fix-everything.sh," grab a caffeinated beverage
> or three and fire up your favorite VOD client while the mess gets
> magically cleaned up by robots somehow.
Sadly := can't help here since gcc switches occur independently of
package installs. And AFAIK revdep-rebuild doesn't help either.
--
Best regards,
Michał Górny
<http://dev.gentoo.org/~mgorny/>
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 949 bytes --]
next prev parent reply other threads:[~2015-11-30 6:43 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-30 3:56 [gentoo-dev] impending c++11 clusterfuck? Gregory M. Turner
2015-11-30 4:10 ` C Bergström
2015-11-30 8:52 ` Mikhail Korolev
2015-11-30 6:42 ` Michał Górny [this message]
2015-11-30 8:07 ` Anthony G. Basile
2015-11-30 9:52 ` Michał Górny
2015-11-30 11:17 ` Anthony G. Basile
2015-11-30 11:31 ` Anthony G. Basile
2015-11-30 18:34 ` Greg Turner
2015-11-30 18:37 ` Greg Turner
2015-11-30 22:49 ` C Bergström
2015-12-01 8:59 ` Benda Xu
2015-12-01 9:03 ` Anthony G. Basile
2015-12-01 11:25 ` Michał Górny
2015-12-01 12:18 ` Anthony G. Basile
2015-12-02 2:12 ` Gregory M. Turner
2015-12-02 7:06 ` Michał Górny
2015-12-02 7:38 ` Anthony G. Basile
2015-12-02 12:54 ` Patrick Lauer
2015-12-02 10:00 ` Gregory M. Turner
2015-12-02 12:57 ` Michał Górny
2015-11-30 10:16 ` Greg Turner
2015-11-30 10:42 ` Greg Turner
2015-11-30 9:18 ` Gregory M. Turner
2015-11-30 9:58 ` Michał Górny
2015-11-30 16:48 ` Steven Lembark
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20151130074235.5a0fec7b.mgorny@gentoo.org \
--to=mgorny@gentoo.org \
--cc=gentoo-dev@lists.gentoo.org \
--cc=gmt@be-evil.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox