C++ ABI RFC [was Re: C++/libiberty PATCH for many mangling fixes (6057, 48051, 50855, 51322, etc)]

[Benjamin Kosnik]

> I like the idea, but not very strongly.  I can live with having to say
> -std=c++11 (which I do via shell functions or scripts)

Well, the actual C++11 compile/runtime environment is going to be more
than just -std=c++11. It's looking something like -std=c++11
-fabi-version=7 + versioned namespaces + other container changes.
 
That's why I'd like to have a configure option.

> My completely unfounded prediction is that many G++ users will move to
> C++11 a lot quicker than the C community moved to C99.

Here's hoping!
 
> As an aside, how do you feel about starting to make those ABI breaking
> changes in the __7 versioned namespace?  There are changes we know we
> need to make for C++11 conformance, but can't without breaking the
> ABI.  If users explicitly select an incompatible ABI via the versioned
> namespace and .so.7 then there's no reason not to give them the best
> possible C++11 support we can, right?

You seem to have answered this in follow-up email. Note that versioned
namespaces impact C++03 and C++11 std components, so switching just for
C++11 is a non-starter. So, we might as well just do this all at once...

-benjamin