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Re: Why does -Wabi-tag complain when -std=c++03?
- From: Jonathan Wakely <jwakely dot gcc at gmail dot com>
- To: Jeffrey Walton <noloader at gmail dot com>
- Cc: "gcc-help at gcc dot gnu dot org" <gcc-help at gcc dot gnu dot org>
- Date: Thu, 24 Mar 2016 17:02:53 +0000
- Subject: Re: Why does -Wabi-tag complain when -std=c++03?
- Authentication-results: sourceware.org; auth=none
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On 24 March 2016 at 16:43, Jeffrey Walton wrote:
> There are lots of folks who have experienced the issue; check out
> http://bugs.debian.org/cgi-bin/pkgreport.cgi?tag=libstdc%2B%2B-cxx11;users=debian-gcc@lists.debian.org.
> Debian happened to say "f**k it, we'll just recompile everything under
> the new ABI and be done with it". But they experienced the corner-case
> issues too. I don't know why they did not consult with the GCC folks.
They did. Rebuilding everything is the right choice. For Debian to
modify all their libraries to use a "dual ABI" and ship those modified
versions would take months, probably years, and would require ongoing
maintenance as the modified versions diverge from upstream.
> I'm the type of person who wants to get a definitive or authoritative
> answer so I can make informed decisions. That's why I come here to ask
> the experts.
>
> This step was not obvious to me at all. I don't ever recall having to
> define a library macro for a library:
>
> $ g++ -D_GLIBCXX_USE_CXX11_ABI=0 -c test.cxx -o test-v1.o
> $ g++ -D_GLIBCXX_USE_CXX11_ABI=1 -c test.cxx -o test-v2.o
>
> Naively, because of the blog post on the coexistent implementations, I
> was looking for an option like -dual-abi to do it for me.
Which is a leap that doesn't in any way follow from a literal reading
of the blog post!