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Re: C++ ABI RFC [was Re: C++/libiberty PATCH for many mangling fixes (6057, 48051, 50855, 51322, etc)]
- From: Benjamin Kosnik <bkoz at redhat dot com>
- To: Jason Merrill <jason at redhat dot com>
- Cc: gcc at gcc dot gnu dot org, libstdc++ at gcc dot gnu dot org
- Date: Fri, 13 Jan 2012 09:45:14 -0800
- Subject: Re: C++ ABI RFC [was Re: C++/libiberty PATCH for many mangling fixes (6057, 48051, 50855, 51322, etc)]
- References: <4F0769D4.2070802@redhat.com> <4F0C4BB7.1090009@redhat.com> <20120112111646.42c5fc0c@shotwell> <4F0F49E1.6070802@redhat.com>
> > As it turns out, the mangling changes don't really impact the
> > explicit instantiations compiled in to libstdc++.so. So, it seems
> > possible to say
>
> Right, so people can use -fabi-version=0 and still use the installed
> libstdc++.
>
> > I think a compelling case could be made to ship 4.7 with a
> > configure-time flag that sets the default C++ dialect to C++11.
>
> I don't think so. Maybe 4.8.
Sure. I will bring it up again then.
> I expect more mangling fixes in the future; most notably, we don't
> test for instantiation-dependent expressions, so our mangling
> oversimplifies some symbols. I ought to open a PR for this.
Interesting. Please cc me on this PR.
Note that one of the objectives of this email is to try and get
maintainers from thinking there is going to be "a perfect time" to
switch. Development history tells us there will always be more changes.
We've been sitting on ABI-breaking changes since 2003.
So, the smart thing to do is to plan a transition..... and to allow
testing in an easy and reproducible manner beforehand. The more time
the better.
-benjamin