Re: propagation of usage-requirements

From: David Abrahams (dave_at_[hidden])
Date: 2004-12-16 10:52:00

Vladimir Prus wrote:
> Toon Knapen wrote:
> 
>>> OTOH, I can't see any case where propagating usage requirements all the
>>> way up will hurt, so maybe it's time to revise the behaviour. Opinions?
>> 
>> 
>> I definitly think it would be better to not only propagate
>> usage-requirements to the direct dependents but also to the indirect
>> dependents (i.e. dependents of dependents and so forth).
> 
> Done -- change and a test are committed. (Patch attached for reference).
> Let's see what comes of it.

I have a lot of sympathy for the idea that mysterious unneeded #include
and library search paths shouldn't show up in a target's build command
just because of some long dependency chain. People will eventually (for
debugging purposes at least) want to know what concrete command was used
to build their software and it will be confusing and probably
distressing if there's a bunch of unneccessary garbage in the
command-line. That's one reason I feel strongly about eliminating the
../../../../back/to/my/directory chains. If nothing else they induce a
lack of confidence in the build system.

There ought to be a way to say "these are propagated only to direct
dependents." In fact, I think that maybe ought to be the normal case.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com