Re: Using C++11

[Chris Vine <chris cvine freeserve co uk>]

On Tue, 30 Jun 2015 08:32:43 +0200
Murray Cumming <murrayc murrayc com> wrote:
> On Mon, 2015-06-29 at 19:44 +0100, Chris Vine wrote:
> [snip]
> > Fedora 23, which will use gcc-5.1 with the new ABI, will have to
> > recompile all its C++ binaries (libraries and programs)[1], for all
> > versions of C++ those libraries and programs may happen to use.
> [snip]
>
> And would you agree that Ubuntu (for instance) will have to do the
> same thing when C++11 (--std=c++11) becomes the default in g++ 6,
> when they use g++ 6?

No.  Assuming gcc-6 still provides libstdc++ with both ABIs (my guess
is that gcc will do so for a considerable number of releases), then it
would depend on whether ubuntu chooses to use the new ABI instead of
the old one for its C++ binaries.

The overarching point is that this would not depend on -std=c++11
becoming the default, because that determines the default API, not the
ABI.

On a different point, if gcc is to change the default API, then it seems
to me more sensible that the default should be -std=c++14.

Chris