On Tue, Oct 10, 2017 at 9:05 AM, Julien Cristau <jcris...@debian.org> wrote: > On Tue, Oct 10, 2017 at 08:45:49 +0200, Mathieu Malaterre wrote: > >> Dear all, >> >> Since the GCC 6 release [1], the default mode for C++ is now >> -std=gnu++14 instead of -std=gnu++98. What this means is that upon >> (re)compilation a library written for c++98 will be recompiled using a >> different c++ standard (c++14 in this case), unless of course the >> upstream package explicitly set the -std= flags with the appropriate >> c++ version. >> >> The ISO committee generally describe the change in between different >> standards [2] and in some case, one can find examples of subtle change >> in behaviors [3] and [4]. >> >> With this mind I'd like to make mandatory the -std=c++XY flags when >> compiling either a c++ library or a stand-alone c++ program: >> >> 1. Either upstream define the explicit -std=c++XY flags by mean of its >> build system, >> 2. Or the package maintainers needs to explicit change the CXXFLAGS to >> pass the appropriate version of the c++ standard. In which case this >> should be documented in the README.Debian file. >> 3. As a fallback, dh should initialize the CXXFLAGS with -std=gnu++98 >> > It might be useful to explain what problem you think that would fix. > The above sounds to me like a step backwards.
You removed the links. But I assumed you saw there were removed and deprecated features. Which means using this explicit mechanism a Debian package will not FTBFS -say- whenever the next GCC release jump from -std=gnu++14 to -std=gnu++17. This also clearly defines the ABI of the shared libraries which IMHO is also a good things (with regards to symbols). And to a lesser extend the subttle difference in between c++98 / c++11 and C++14 are clearly avoided (while I admit no sane person will provide a c++ project using an examples from the provided SO links I sent). >> If there is a consensus on the following change, I'll go ahead and >> also file a bug for lintian to scan the compilation logs in search for >> missing -std=c++ expression when g++ command line are issued. >> > lintian doesn't scan build logs, it scans source and binary packages. Right. I always forgot that. What is the mechanism used for shlib-calls-exit, does it rely on source parsing ?
