Re: [Boost-build] threading=multi and msvc

From: Johan Nilsson (r.johan.nilsson_at_[hidden])
Date: 2006-11-14 03:46:26

David Abrahams wrote:
> "Johan Nilsson" <r.johan.nilsson_at_[hidden]> writes:
>
>> Roland Schwarz wrote:
>>> Johan Nilsson wrote:
>>>> +1 for generating an error.
>>>
>>> Sure?
>>
>> Yes.
>>
>>> Consider:
>>>
>>> The author has the intent to
>>> <threading>single <runtime-link>shared
>>>
>>> She specifies this in a platform independent manner.
>>>
>>> Now on platform A this might indeed work.
>>>
>>> But on platform B (e.g. windows) it won't.
>>
>> Isn't this more of a compiler-specific issue than O/S specific? I
>> get your point though.
>>
>>>
>>> Would you expect, only platform B generating an
>>> error, or fall-back B to a safe emulation?
>>
>> I'd prefer only platform B generating an error. If I explicitly
>> request a shared runtime library I'd like to either get it, or fail.
>
> I think we need to distinguish "requires a shared runtime" from
> "I prefer a shared runtime if one is available."

Good point. Would it be possible to make that distinction stand out better 
in some way?

>
> I was under the impression that we made that distinguish by putting
> <runtime>shared either in requirements or in a default build request.

So, in the case of requirements, either via command-line options or through 
the Jamfiles, the above example should fail.

In the case of a default build request, a graceful fallback to either a 
"safe emulation" or simply not to build that variant would be ok.

I've read the earlier discussion in the "Building Boost and impossible 
features" thread and I think this is similar to what the conclusions were 
there.

/ Johan