Can I use variadic templates (but none of the other c++0x features) in g++?

The thinking is that since variadic templates are a compile time feature, there will be little ABI impact or runtime behaviour change. Is this possible?

I specifically want the benefit of faster compile times for boost::mpl::vector and boost::mpl::string.

Rephrasing the question...

Is it possible to mix c++03 and c++开发者_如何学Go11 code by separating them into libraries? I.e. we use quite a few 3rd party c++ libraries which are compatible with gcc 4.3 but we are moving on too gcc 4.7 and intend to use c++11 features where possible/makes sense. Or is it impossible to mix c++11 and c++03?

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You should compile and link everything using the same tools running in compatible modes. You can't cherry-pick features like this.

The ABI impact comes in, for example, increased virtual function tables for standard I/O classes. It is not safe to mix things around.

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I cant give a qualified answer, but from what I understood is, that lots of people would be concerned if this kind of backward-compatibility would be broken. As far as I understood there is nothing in the new C++11 that makes it necessary to rebuild everything. Thus, it could only be your specific compiler that would make that necessary. For the GCC I dont't expect it, although, the different libstdc++ versions could create "issues".

My strong guess is, that on a typical (intel-) linuxes you should be able to create two independent libs with different decently new versions of the gcc (maybe >4.x) and use/link them into a final program. You may have some things in there twice, though. I had some minor solvable issues with threads in 4.7.0 and <thread>. I don't know if they would create a good or bad mix with other thread-libs (eg. boost). However, you don't want to use gcc-4.7.0 for your production code, yet. And before a final gcc compiler is out, only a statement from the responsible projects team can give you certainty.