Re: [boost] Are some of the trunk regression tests running in C++0x mode when they shouldn't be?

Subject: Re: [boost] Are some of the trunk regression tests running in C++0x mode when they shouldn't be?
From: Christopher Jefferson (chris_at_[hidden])
Date: 2011-11-10 18:37:46

On 10 Nov 2011, at 23:30, Gennadiy Rozental wrote:

> Vicente J. Botet Escriba <vicente.botet <at> wanadoo.fr> writes:
> 
>> 
>> Le 10/11/11 21:13, Gennadiy Rozental a écrit :
>>> Steven Watanabe<watanabesj<at>  gmail.com>  writes:
>>>>> Looks like -std=c++0x is being specified when it shouldn't for some reason?
>>>>> Is something broken, or am i imagining it?
>>>>> 
>>>> This is a problem in Boost.Test as of r75372.
>>> How should I specify in Jamfile that I want to require c++11 support from gcc
>>> starting with version a.b.c?
>>> 
>> You should not require this. Even if using a given version of gcc, users 
>> could been to preserve a C++03 behavior.
> 
> What is the problem with enabling C++11 features if possible? We do not expect
> backward compatibility issues, don't we?
> 
> What about MSVC? It has C++11 enabled by default. 
> 
> Some of the new features of Boost.Test require c++11 support. I want to be able
> to test it and I want users to be able to use it.

There are two problems with enabling C++11 unconditionally in gcc:

1) It breaks binary compatability of some stl containers
2) Different versions of gcc support different amounts of C++11. In particular, there are at least 2 (maybe 3?) different semantics for rvalue references floating around. In general, I would advise only trying to use boost in C++11 mode in g++ 4.5 at least. I don't think it's worth the effort to make boost work with each of the early partial implementations floating around in the various compilers.

Chris