GCC 5 for 14.10 (wily) on July 31

[Dimitri John Ledkov]

On 23 July 2015 at 12:39, David Henningsson
<david.henningsson at canonical.com> wrote:
>
>
> On 2015-07-20 23:44, Matthias Klose wrote:
>>
>> Hi,
>>
>> We are currently preparing the switch to GCC 5 as the default compiler for
>> 14.10
>> (wily).  Unlike earlier updates to newer compiler versions, which only
>> required
>> updating packages to newer language standards, this time we have a partial
>> ABI
>> transition in the standard C++ library (libstdc++6).
>
>
> That sounds scary, but maybe it's not as scary as it sounds. Will this also
> affect everyone outside the main repo distributing binary packages (e g,
> Google Hangout)?
>
> How will the versioning of libstdc++ look like, in order to make sure no
> packages are linking against a libstdc++ they are incompatible with?

So libstdc++ 98 abi is not broken, and old 98abi symbols are still provided.
However the c11 abi was broken (there are small number of packages
that use c11 abi from before 5.x release).
And finally newly compiled libraries against the new libstdc++ will
use c11 abi, not 98abi.
Depending on what those libraries export as an api, they may become
incompatible (e.g. if they wrapped std::string, it will now become a
different one).

Do you have a list of libraries that e.g. google hangouts link
against? if it only links against libstdc++ in 98abi it should
continue to work.

If on the other hand it uses other c++ libraries from the host, ISV
might require to recompile it for willy and up.

-- 
Regards,

Dimitri.