Re: how to override precious variables for subdirs

[Ralf Wildenhues]

Hello Chris,

* Chris Frey wrote on Fri, Apr 22, 2011 at 10:53:29PM CEST:
> I have a software package (Barry) that contains a number of subdirectories,
> using the AC_CONFIG_SUBDIRS feature.
> 
> These subdirectories depend on the library that is built in the main tree.

Interesting.  Most subpackage setups I've come across work depth-first,
i.e., upper level packages depend on stuff built in sub packages.

> Normally, I just export PKG_CONFIG_PATH to include the main tree, so
> that the subdirectories' configure scripts can find the library.
> 
> Recently, PKG_CONFIG_PATH has become precious.  This means that when the
> subdirectory configures are run, then PKG_CONFIG_PATH is set on the
> command line, if it was set for the main directory.
> 
> So far, I have been unable to find any way to override this precious state
> for subdirectories.
> 
> Is there a way to override this?  Is there a better way to achieve the
> same ends?

I don't think it's possible to override precious-ness at configure time.
It may be hackable from within configure.ac, but that strategy doesn't
seem advisable.

It is possible to amend or modify $ac_configure_args from within the
toplevel configure (watch out with quoting, its contents are to be
eval'ed later), but that might mean you'd have to turn off config.cache.

Incidentally, a patch has been proposed quite recently to add extra
arguments to (some) sub package configure invocations.  It is still
pending copyright assignment clearance before review, but definitely
interesting.  It might help you.  However, given the preciousness it
might also mean that an eventual config.cache file cannot be shared
between the different configure scripts.

Hope that helps.

Cheers,
Ralf