Is it safe to package C++11 software on current Linux distributions?

Question

As a downstream maintainer in a Linux distribution, some of the packages that I usually maintain are starting to use the C++11 features in their code base. All of them depend on different libraries packaged by the Linux distributions.

Problems with the ABI could appear when mixing C++11 code with C++98 and AFAIK, most of the current major Linux Distributions are not enabling the C++11 flag by default when compiling software to generate packages.

The question is: How are the major Linux distributions handling the entry of C++11 code? Is there a decent way of checking or avoiding these problems with the ABI when using system libraries?

Thanks.

Answer 1

The issue has nothing to do with C++11 vs C++98 except that C++11 can motivate binary changes. There is nothing special about binary changes motivated by C++11. They are just as breaking or non-breaking as regular binary changes. Furthermore, they are only changed if the library maintainer specifically chooses to change his binary interface.

In other words, this has nothing to do with the Standard version and everything to do with the library, unless the library explicitly chooses to offer two different binary interfaces to different Standard versions (which is still a library choice). Excepting this case, you are just as broken in C++98 as you are in C++11. Itanium is backwards compatible between the C++11-supporting versions and the C++98-supporting versions, so the compiler ABIs are not broken.

From memory, unless you're using 4.7.0 which they broke for fun and then unbroke, you're pretty much safe with libstdc++- they are storing up ABI breakage for a future release when they can make one big break.

In other words, whilst the transition period to C++11 can introduce additional motivation to break ABI and therefore additional risk, actually using C++11 itself does not introduce any additional risk.