[Boost-users] C++11 ABI stability

[Marek Skalický via Boost-users]

Hi,
mongo-cxx-driver notices this:
"Important note about C++11/C++14: The boost libraries do not offer a
stable ABI across different versions of the C++ standard. As a result,
you must ensure that your application, the C++ driver, and boost are
all built with the same language standard. In particular, if you are
building the C++ driver with C++11 enabled, you must also build your
application with C++11 enabled, and link against a C++11 compiled
boost. " [1]

Is it true? What changes with new standard? (or is this only related to
ABI change in gcc introduced by c++11?)

I'm interested mainly in libraries: filesystem, chrono, thread, system
and regex

Thanks,
Marek

[1] http://mongodb.github.io/mongo-cxx-driver/legacy-v1/installation/#s
cons-options-when-compiling-the-c-driver
_______________________________________________
Boost-users mailing list
Boost...@lists.boost.org
https://lists.boost.org/mailman/listinfo.cgi/boost-users

[Steve Lorimer via Boost-users]

They are probably referring to the changes wrt std::string and std::list

Pre-C++11 a lot of standard libraries used copy-on-write strings, which was forbidden in C++11.

std::list now has to have O(1) size, which is another possibly ABI incompatible change.

More details here: https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html

[Matthieu Brucher via Boost-users]

Well, as soon as you have a string, you may have incompatibilities. And lots of Boost libraries do use them.

2017-06-21 16:16 GMT+01:00 Edward Diener via Boost-users <boost...@lists.boost.org>:

On 6/21/2017 2:09 AM, Marek Skalický via Boost-users wrote:

Hi,
mongo-cxx-driver notices this:
"Important note about C++11/C++14: The boost libraries do not offer a
stable ABI across different versions of the C++ standard. As a result,
you must ensure that your application, the C++ driver, and boost are
all built with the same language standard. In particular, if you are
building the C++ driver with C++11 enabled, you must also build your
application with C++11 enabled, and link against a C++11 compiled
boost. " [1]

Is it true? What changes with new standard? (or is this only related to
ABI change in gcc introduced by c++11?)

I'm interested mainly in libraries: filesystem, chrono, thread, system
and regex

I can't speak for the libraries you mention above. But regarding Boost libraries in general many Boost libraries are unaffected in their public interface whether you compile with C++03, C++11, C++14, or C++17 support. If a library is affected in its public interface depending on the level of C++ support it should document this and, needless to say if it is a built library whether static or shared, it should have a distinct library name depending on its differing public interfaces.

Thanks,
Marek

[1] http://mongodb.github.io/mongo-cxx-driver/legacy-v1/installation/#s
cons-options-when-compiling-the-c-driver

_______________________________________________
Boost-users mailing list
Boost...@lists.boost.org
https://lists.boost.org/mailman/listinfo.cgi/boost-users

--

Information System Engineer, Ph.D.
Blog: http://blog.audio-tk.com/
LinkedIn: http://www.linkedin.com/in/matthieubrucher

[Edward Diener via Boost-users]

On 6/21/2017 2:09 AM, Marek Skalický via Boost-users wrote:

> Hi,
> mongo-cxx-driver notices this:
> "Important note about C++11/C++14: The boost libraries do not offer a
> stable ABI across different versions of the C++ standard. As a result,
> you must ensure that your application, the C++ driver, and boost are
> all built with the same language standard. In particular, if you are
> building the C++ driver with C++11 enabled, you must also build your
> application with C++11 enabled, and link against a C++11 compiled
> boost. " [1]
>
> Is it true? What changes with new standard? (or is this only related to
> ABI change in gcc introduced by c++11?)
>
> I'm interested mainly in libraries: filesystem, chrono, thread, system
> and regex

I can't speak for the libraries you mention above. But regarding Boost

libraries in general many Boost libraries are unaffected in their public
interface whether you compile with C++03, C++11, C++14, or C++17
support. If a library is affected in its public interface depending on
the level of C++ support it should document this and, needless to say if
it is a built library whether static or shared, it should have a
distinct library name depending on its differing public interfaces.

>

[Miloslav Marik via Boost-users]

The problem is in ASIO library. S.

[Jonathan Wakely via Boost-users]

On Wed, Jun 21, 2017 at 08:44:53AM -0500, Steve Lorimer via Boost-users wrote:
> They are probably referring to the changes wrt std::string and std::list
>
> Pre-C++11 a lot of standard libraries used copy-on-write strings, which was
> forbidden in C++11.
>
> std::list now has to have O(1) size, which is another possibly ABI
> incompatible change.
>
> More details here:
> https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html

That page explicitly points out that choosing a standard version with
-std does not affect the ABI:

"Although the changes were made for C++11 conformance, the choice of ABI
to use is independent of the -std option used to compile your code, i.e.
for a given GCC build the default value of the _GLIBCXX_USE_CXX11_ABI
macro is the same for all dialects. This ensures that the -std does not
change the ABI, so that it is straightforward to link C++03 and C++11
code together."

[Miloslav Marik via Boost-users]

Hi, 

As far as I can remember, the problem with ABI compatibility was with boost/asio/detail/atomic_count.hpp. You can force ABI compatibility using BOOST_ASIO_DISABLE_STD_ATOMIC definition. I have not detect any other ABI compatibility problem between C++03 and C++11.

Best Regards, 

Slavek 

[Marek Skalický via Boost-users]

Thank you all for your answers.

So generally boost is not affected by -std=c++XY. Asio library is
exception. I hope I get it right.

Probably mongo-cxx-driver upstream was referring to gcc dual ABI
problem and that it can affect Boost too.

Thanks again,
Marek

Miloslav Marik via Boost-users píše v St 21. 06. 2017 v 17:23 +0200:

> The problem is in ASIO library. S.
>

> 2017-06-21 15:44 GMT+02:00 Steve Lorimer via Boost-users <boost-users
> @lists.boost.org>:
> > They are probably referring to the changes wrt std::string and
> > std::list
> >
> > Pre-C++11 a lot of standard libraries used copy-on-write strings,
> > which was forbidden in C++11.
> >
> > std::list now has to have O(1) size, which is another possibly ABI
> > incompatible change.
> >
> > More details here: https://gcc.gnu.org/onlinedocs/libstdc++/manual/
> > using_dual_abi.html
> >

> > On 21 June 2017 at 01:09, Marek Skalický via Boost-users <boost-use