Re: [Boost-build] Enforcing missing properties to cause warning or error messages

From: Vladimir Prus (ghost_at_[hidden])
Date: 2008-04-06 05:59:27

On Sun, 6 Apr 2008 11:45:06 +0200
"Peter Schueller" <schueller.p_at_[hidden]> wrote:

> On Sun, Apr 6, 2008 at 6:56 AM, Vladimir Prus <ghost_at_[hidden]> wrote:
> >  2. If you know for sure that CPP files created with different
> > value of the feature are identical, and always will be, you have to
> > remove the feature from the property set associate with the CPP
> > file.
> >
> >  The example generator has this code:
> >
> >                 # Produce one output, using just copy.
> >                 local a = [ new action $(sources[1])
> >                   : common.copy : $(property-set) ] ;
> >                 local t = [ new file-target $(name) : CPP :
> > $(project) : $(a) ] ;
> >
> >  which can be modifier as follows:
> >
> >         local raw = [ $(property-set).raw ] ;
> >         local stripped = [ property.change $(raw) :
> > <gsoap.usage> ] ; local a = [ new actions $(sources[1]) :
> > common.copy : [ property-set.create $(stripped) ] ;
> >         local t = [ new file-target $(name) : CPP : $(project)
> >                   : $(a) ] ;
> >
> >
> >  In this case, the gsoap.usage property won't be associated with the
> >  target and the call to virtual-target.register will no longer
> > complain that two different targets are associated with the same
> > filename.
> >
> >  Note: the above is untested, so some *details* might be wrong. It
> > should work overall.
> 
> I only use the property to pass some information to the generator so
> that the generator can decide which CPP files from the action are
> passed to the target, i.e. which CPP files get linked into the final
> LIB or EXE. Therefore I could use the method from above.
> 
> But this does not work, and I think the reason is the following fact
> stated in property-set.jam:
> 
>  13 # - there's 1<->1 correspondence between identity and value. No
> two instances of
>  14 #   the class are equal. To maintain this property, the
> 'property-set.create'
>  15 #   rule should be used to create new instances. Instances are
> immutable.
> 
> With your method I create two content-wise equal property-sets but
> virtual-target still gets no instance equality

This should not happen. property-set.create is exactly the method that
ensured the 1-1 correspondence between identity and value.

> and complains about a
> duplicate target (see attached output.txt)
> 
> This seems similar to this problem
> http://lists.boost.org/boost-build/2005/11/12089.php which was fixed
> in http://svn.boost.org/trac/boost/changeset/31830 but I do not
> understand how this changeset fixed it and if it applies to my
> problem.

Just in case -- are you sure all targets you create get passed via
virtual-target.register?

If yes, then please send me a minimal complete project that reproduces
the problem, and I will take a look.

Thanks,
Volodya