On Wed, Aug 06, 2014 at 11:04:14AM +0200, Richard Biener wrote:
> On Wed, Aug 6, 2014 at 10:48 AM, Jakub Jelinek <[email protected]> wrote:
> > - libstdc++ ABI changes (it is a significant user visible change,
> > if you rebuild everything, no extra effort is needed, but otherwise
> > if you want some C++ code built with older compilers work together
> > with code built with newer compilers, it might require source code
> > changes (the abi_tag attribute additions where needed and warning
> > suggest to put those at), at least that is my current understanding
> > of the plans
>
> But that's only with -std=c++11? Which had no compatibility
> guarantees before?
>
> > - likely libgfortran ABI changes (different array descriptors)
>
> Let's wait and see ...
>
> We'll find a good reason to bump the major with every release.
> Like for 4.9 LTO defaults to slim-objects, or C++ rejecting even more
> invalid code, or libstdc++ header re-orgs, or defaulting to dwarf4+
> (or even support for it), or VTA, or ...
>
> Where do we set the barrier? GCC isn't a C++ (or Fortran) compiler
> only.
>
> So if we change to 5.1 (please not .0) then let's switch the default
> optimization level to -O2! _That's_ a user-visible change across
> the board.
I'm planning to move the default C standard from gnu90 to gnu11
(Currently it's blocked on the -Wc90-c99-compat warning).
That's a pretty big user-visible change as well, I suppose.
Marek
