Re: [jamboost] Duplicate name of target and SEARCHED_LIB

From: Vladimir Prus (ghost_at_[hidden])
Date: 2003-03-28 02:26:09

Hi Andre,
> Problem:
> link against libraries with different names under different toolsets
>
> My solution:
> project a ;
> lib b : : <name>libb <toolset>gcc ;
> lib b : : <name>b <toolset>msvc ;
> lib a : main.cpp b : <link>static ;
> # somehow the problem goest away with <link>shared
>
> The error:
> error: Duplicate name of actual target: <.>b
> previous virtual target { b.SEARCHED_LIB }
> another virtual target { b.SEARCHED_LIB }

Nice! Our safeguards get into the way. If we did not check for duplicate 
names, we'd work just fine.

> I hacked virtual-target.jam to allow two searched-libs with the same name
> but I'm afraid that is not the rigth solution. Anyone cares to shed some
> light on this? 

The problem is that 'searched-lib-target' is not associated with build 
properties. There's lengthy comment in 'searched-lib-generator.run'
(around line 407 of builtin.jam/CVS version), explaining why this is OK.

Alas, two different searched-lib-targets get the same Jam name and the
error above. Moreover, it's not possible to get properties from 
searched-lib-target. Ali hit this problem already --- he can't find out what 
other libraries searched-lib-target depends on, which is needed to compute
correct order of libraries on gcc's command line.

> Obviously, one can (sometimes) rename the libraries or use
> an 'if' clause (not very elegant).

Yes, this should not be required. I think we need to attach properties to 
searched-lib-target instances. The plan is simple:

- remove the long comment in searched-lib-generator.run
- create a 'null-action' instance. That class is used when we only 
need to assign properties to targets. 
- assign this action instance to searched-lib-target instance, something like:

t = [ new searched-lib-target ... ] 
a = [ new null-action $(t) : $(property-set) ] ;
$(t).action $(a) ;
return $(t)

Do you have the inclination to try pushing this outline into a finished patch? 
I'll write a regression test, in the meantime.

- Volodya