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

From: Konstantin Litvinenko (Konstantin.Litvinenko_at_[hidden])
Date: 2007-04-19 01:23:32

Hello, David!
You wrote  on Wed, 18 Apr 2007 11:01:27 +0100:

 ??>>     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.

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

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

 DA>   and

 DA>        bjam test

    That is because we have buggy behaviour when only one alternative 
exists. Above will fail if we fix it. In past when we had link incopability 
features above can't be executed.

 DA> We need to decide if <threading>single with <threading>multi is a link
 DA> incompatibility on this platform, and we need to decide if we want to
 DA> enforce that they not be combined.

    Here you are right.

With best regards, Konstantin Litvinenko.