Re: [boost] ABI issues with -std

Subject: Re: [boost] ABI issues with -std
From: Edward Diener (eldiener_at_[hidden])
Date: 2018-08-19 19:56:15

On 8/19/2018 11:17 AM, Peter Dimov via Boost wrote:
> At some point, we'll need to acknowledge the problem which results from 
> building Boost with one -std and user code with another, and deal with 
> it somehow, if just by documenting.
> 
> Most of our libraries don't suffer from it at the moment but 
> Boost.System does, because of my changes; its ABI changes between 
> 03/11/14. So I'm going to take the initial hit. :-)
> 
> POSIX platforms have long been able to ignore ABI issues so we don't 
> mangle the library names there at all, but now whether one builds Boost 
> for C++03, C++11 or C++14 matters, and there's nothing to prevent 
> linking C++xx to C++yy. Even with --layout=versioned, the cxxstd level 
> is not encoded.
> 
> The fact that the default C++ standard differs between g++ and clang++ 
> doesn't help; when following the instructions of doing "b2 install", 
> with g++6 and above you get C++14, but with g++5 or clang++ you get 
> C++03. The latter is very rarely what one wants today.

Are not ABI changes a compiler issue ? I do not see that there is any 
inherent reason why building code with some -std, and using it with code 
built to another -std, should cause ABI issues when the compiler remains 
the same. I admit I do not know whether ABI compatibility is addressed 
by the C++ standard itself, although I expect not.