From: "Anton Wöllert" <a.woellert@gmail.com>
To: Jonathan Wakely <jwakely.gcc@gmail.com>
Cc: "gcc@gcc.gnu.org" <gcc@gcc.gnu.org>
Subject: Re: Relation between gcc version and libstdc++ version
Date: Tue, 30 Aug 2022 18:53:17 +0200 [thread overview]
Message-ID: <0951c3b4584404fab95dd7d92af8b6f301b758c7.camel@gmail.com> (raw)
In-Reply-To: <CAH6eHdQVD3osSpX+v8R=ALQtBJiWAtVKRY+TNssGR8g8GbauHw@mail.gmail.com>
Hi Jonathan,
thank you for your reply!
On Tue, 2022-08-30 at 17:09 +0100, Jonathan Wakely wrote:
>
>
> On Tue, 30 Aug 2022, 15:48 Anton Wöllert via Gcc, <gcc@gcc.gnu.org>
> wrote:
> > If this libstdc++ is
> > newer than the one one the target, I get undefined references
> > (because
> > there are some newer implementation details and things like that).
>
> Then you're not telling the executable how find the new libstdc++.
>
>
https://gcc.gnu.org/onlinedocs/libstdc++/faq.html#faq.how_to_set_paths
>
>
I tried to do that. If I let the toolchain use it's own libstdc++.so,
then I get at runtime unresolved symbols due to the version mismatch
(these GLIBCXX errors). This is clear.
If I force the toolchain to link against the older target libstdc++,
then I get undefined symbols at compile time, because it is still using
it's own shipped headers for the newer libstdc++, which have
implementation details that use newer "functions/symbols" that are not
available in the old libstdc++.
If I furthermore remove the shipped headers and force it to include the
c++ headers from the older libstdc++, then everything works out.
But this whole "patching" seems very hacky.
> > Is
> > it possible to tell G++/GCC to use the libstdc++.so from the target
> > and
> > also to use the C++ headers (like iostream) from the target?
>
> It's possible, but unsupported and probably won't work.
So it seems to be indeed possible, but not intended.
>
> > If not, is there any reason this is hard-coded?
>
> The libstdc++ headers are tightly coupled to the GCC version, so
> headers from a given GCC release might not even compile with a newer
> or older GCC.
I would see an argument if you're trying to compile an newer libstdc++
with an older gcc - but why not the other way around? C++ in general
tries to be very good in backward compatibility.
This essentially means that you can't use newer compilers with more
features/bugfixes to compile software for older targets.
Is there any obvious reason this is not supported? Clang, for example,
also seems to be able to compile/link against different libstdc++
versions. I'm just wondering.
Best,
Anton
next prev parent reply other threads:[~2022-08-30 16:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-30 14:47 Anton Wöllert
2022-08-30 16:09 ` Jonathan Wakely
2022-08-30 16:09 ` Jonathan Wakely
2022-08-30 16:53 ` Anton Wöllert [this message]
2022-08-30 17:20 ` Jonathan Wakely
2022-08-30 17:20 ` Jonathan Wakely
2022-08-30 17:21 ` Jonathan Wakely
2022-08-30 17:21 ` Jonathan Wakely
2022-08-30 18:46 ` Anton Wöllert
2022-08-30 19:24 ` Jonathan Wakely
2022-08-30 19:24 ` Jonathan Wakely
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=0951c3b4584404fab95dd7d92af8b6f301b758c7.camel@gmail.com \
--to=a.woellert@gmail.com \
--cc=gcc@gcc.gnu.org \
--cc=jwakely.gcc@gmail.com \
/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;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).