Re: [Boost-build] ** Need input on alternative selection **

From: David Abrahams (dave_at_[hidden])
Date: 2007-04-18 06:01:27

on Wed Apr 18 2007, "Konstantin Litvinenko" <Konstantin.Litvinenko-AT-malva.ua> wrote:

>     Ok. Lets take slightly modified example 3 from your proposal
>
> lib a : a.cpp ;                                           # 1st alternative
> lib a : a-dbg.cpp : <threading>multi <debug-symbols>on ;  # 2nd alternative
> exe test : test.cpp a ;
>
> bjam invocation will be
>
> bjam debug-symbols=on
>
> With your proposal 'test' target will be build against single threaded 
> runtime, but 'a' will be build against multi threaded runtime. For VC 7.1 
> its fatal mistake.

This particular mistake is easy -- even trivial -- to make today even
without target alternatives.

       lib a : a.cpp : <threading>multi ;
       exe test : test.cpp a ;

  and

       bjam test

We need to decide if <threading>single with <threading>multi is a link
incompatibility on this platform, and we need to decide if we want to
enforce that they not be combined.  If so, we need a feature separate
from the algorithm used for alternative selection for dealing with
that problem.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com
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