Re: [Boost-build] Need Help with generators

From: Reece Dunn (msclrhd_at_[hidden])
Date: 2005-11-08 02:48:27

Schnyder Franz wrote:
>> What you want is CPP -> LST -> OBJ and C -> LST -> OBJ, correct? When 
>> compiling a C file with VxWorks, I'm assuming you don't need to "munch" 
>> it. If so, why don't you have C -> OBJ as normal, and
> 
> No not exactly, sorry I did explain ist very precise in my fist mail. 
> 
> So I created the the composing list rule 'OBJ -> LST' which collects all 
> Objects and since muching doesn't care if there are also Objects from C 
> files in the list I just added all objects. Then created the munch rule 
>     'LST -> C'. I compiled the resulting file and then linked all the 
> objects from the lst file and the additional object from the munching 
> into an "executable".

Ok. I think I understand now. With what you have above, you are going to 
run into problems because you have:

    CPP -> LST -> OBJ
    C ---/     \-> C -> OBJ
                   ^^^^^^^^ ambiguity here

So, now IIUC VxWorks needs to compile a C++ program into C code and C 
code can be compiled into object form, so you have:

    generators.register-standard vxworks.compile.c++
       : CPP : C : <toolset>vxworks ; # C++ -> C
    generators.register-standard vxworks.compile.c++
       : C : OBJ : <toolset>vxworks ; # C -> OBJ

Now you have a set of object files that need munching. You can use a 
standard link generator/rule, but instead of...

action link
{
    linker <object-files> output
}

...you will have...

action link
{
    @($(STDOUT):E=$(nl)"$(>)") > "$(<[1]).lst"
    munch "$(<[1]).lst" "$(<[1])_munched.c"
    compile "$(<[1])_munched.c"
    link "$(>)" "$(<[1])_munched.obj"
}

where line:
1 -- generate the list file from the object file inputs;
2 -- munch that list into a C file;
3 -- compile the munch file;
4 -- link in the object files with the munchable file.

This way, you break the ambiguity, but still do the munching.

HTH,
- Reece