Single ABI: C++11

[Jonathan Wakely]

On 19/01/17 14:58 +0000, Cristian Morales Vega wrote:
>The configure script, because of GLIBCXX_ENABLE_LIBSTDCXX_DUAL_ABI and
>GLIBCXX_DEFAULT_ABI, doesn't let you have a single ABI with it being
>the C++11/new one. Is this on purpose? There is any problem I'm not
>aware of with using only the C++11 ABI?

No, it just isn't possible to configure that way yet. That's a bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65762

>I understand there may be a desire to keep backwards compatibility,
>but I am thinking about the case where you are building it for an
>embedded device where the toolchain I create will be the only one to
>ever be used to create binaries running on it. Since I only need one
>ABI, why not to use the new one? (not that I have any specific problem
>using the old one) What I need is to save space, so the dual ABI is
>also not ideal.

Yes, that's the main reason it should be possible.

I also want to make the explicity-non-backwards-compatible
configuration --enable-symvers=gnu-versioned-namespace use the new ABI
(maybe unconditionally, maybe optionally, I'm not sure yet) and enable
various optimizations that can't be done otherwise without breaking
backwards compatibility, such as:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=24693