C++11 and librados C++

C++11 and librados C++

[Samuel Just]

It seems like it's about time for us to make the jump to C++11.  This
is probably going to have an impact on users of the librados C++
bindings.  It seems like such users would have to recompile code using
the librados C++ libraries after upgrading the librados library
version.  Is that reasonable?  What do people expect here?
-Sam

Re: C++11 and librados C++

[Wido den Hollander]

On 03-08-15 22:25, Samuel Just wrote:
> It seems like it's about time for us to make the jump to C++11.  This
> is probably going to have an impact on users of the librados C++
> bindings.  It seems like such users would have to recompile code using
> the librados C++ libraries after upgrading the librados library
> version.  Is that reasonable?  What do people expect here?

Well, some people use Qemu build by their distro, but they use librados
/ librbd from ceph.com

So if they suddenly have to rebuild Qemu that would hurt them I think.

Wido

> -Sam
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Re: C++11 and librados C++

[Sage Weil]

On Tue, 4 Aug 2015, Wido den Hollander wrote:
> On 03-08-15 22:25, Samuel Just wrote:
> > It seems like it's about time for us to make the jump to C++11.  This
> > is probably going to have an impact on users of the librados C++
> > bindings.  It seems like such users would have to recompile code using
> > the librados C++ libraries after upgrading the librados library
> > version.  Is that reasonable?  What do people expect here?
> 
> Well, some people use Qemu build by their distro, but they use librados
> / librbd from ceph.com
> 
> So if they suddenly have to rebuild Qemu that would hurt them I think.

Qemu fortunately is using the C bindings, so it would not be affected.  
It is only the C++ ABI (or lack thereof) that is problematic.

What users of the C++ bindings are there out there?

sage

Re: C++11 and librados C++

[Alex Elsayed]

Sage Weil wrote:

> On Tue, 4 Aug 2015, Wido den Hollander wrote:
>> On 03-08-15 22:25, Samuel Just wrote:
>> > It seems like it's about time for us to make the jump to C++11.  This
>> > is probably going to have an impact on users of the librados C++
>> > bindings.  It seems like such users would have to recompile code using
>> > the librados C++ libraries after upgrading the librados library
>> > version.  Is that reasonable?  What do people expect here?
>> 
>> Well, some people use Qemu build by their distro, but they use librados
>> / librbd from ceph.com
>> 
>> So if they suddenly have to rebuild Qemu that would hurt them I think.
> 
> Qemu fortunately is using the C bindings, so it would not be affected.
> It is only the C++ ABI (or lack thereof) that is problematic.
> 
> What users of the C++ bindings are there out there?

One thing I think is worth noting: GCC 5 represents an ABI break for C++11 
http://developerblog.redhat.com/2015/02/05/gcc5-and-the-c11-abi/

Thus, some serious care is needed to avoid compat hazards when using C++11.