Side targets, stage, and --clean

From: Vladimir Prus (ghost_at_[hidden])
Date: 2003-12-18 02:40:01

For a few last days, I was pondering about a problem I faced with Boost.Build, 
and still don't know the right solution. I'd appreciate fresh look on it.

Suppose I have

lib a : a.cpp ;

Simple, right? Now, via some fancy logic in generators.jam, when building 'a', 
only targets of type 'LIB' are returned. For example, on windows, response 
files are not returned.

However, I have a custom toolset which has to return not only LIB, but also 
additional target of type STATIC_DATA -- since that target will be processed 
later.

One obvious solution is to extend the <include-type> feature to work in this 
case:

lib a : a.cpp : <include-type>STATIC_DATA ;

that's probably enough for me, but it is not nice, since I'd have to put this 
extra requirement on all lib targets.

Another solution is to remove the fancy logic which eliminates some targets. 
This will work for me, and simplify code. Also, this is also needed to fix 
the --clean option. It was requested that --clean does not remove targets in 
other project, or at least in other project roots. Now it removes everything 
bjam sees and that's not nice. But to implement right semantic, all virtual 
targets must be seen and processed by top-level code.

So, this looks like an excellent approach, except for 'stage'.

exe a : a.cpp ;
stage dist : a ;

If 'a' returns all targets, then 'stage' will start to copy response files and 
what not. Is it a problem? I think it's not that nice, but OTOH it won't 
break anything. For real uses, it's easy to add <include-type> features to 
stage only EXES (after I commit recent Pedro's patch). 

Comments?

- Volodya