Re: [Boost-build] CVS: boost/tools/build/new feature.jam,1.41,1.42

From: Vladimir Prus (ghost_at_[hidden])
Date: 2003-05-14 08:25:47

David Abrahams

[side note: Dave, is it possible to set Reply-To header for boost-build 
mainling list to jamboost_at_... list? I think it's better to keep all 
discussion there, even if it originates from commit email].

> > +# Note: if there's there's ordinary feature F1 and composite feature
> > +# F2, which includes some value for F1, and both feature have default
> > values, +# then the default value of F1 will be added, not the value in
> > F2. This might +# not be right idea: consider
> > +#
> > +# feature variant : debug ... ;
> > +# <variant>debug : .... <runtime-debugging>on
> > +# feature <runtime-debugging> : off on ;
> > +#
> > +# Here, when adding default for an empty property set, we'll get
> > +#
> > +# <variant>debug <runtime_debugging>off
> > +#
> > +# and that's kind of strange.
>
> Hi Volodya,
>
> What are the consequences of this possibly-not-right idea? 

I think they are apparent. If I add <runtime-debugging>on to debug variant and 
debug variant is the default one, I expect that by default I'll be buidling 
with debug runtime. But if default value of <runtime-debugging> is off, I'll 
be building with release runtime!

> When does this rule get called?

It's called from property-set.add-defaults which is called from 
main-target.generate. When you don't specify anything on command line, the 
property set will be empty, which leads to behaviour I describe above.

- Volodya