Re: Splitting dependency_libs in *.la?

[Axel Thimm]

Hi,

On Mon, Oct 02, 2006 at 09:00:36PM +0200, Kurt Roeckx wrote:
> On Mon, Oct 02, 2006 at 01:51:58PM +0200, Axel Thimm wrote:
> > dependency_libs contains the linker switches/arguments that this
> > library was built with including the dependent libs, both directly
> > references as well as indirectly references through intermediate libs.
> > 
> > For static linking one needs the whole dependency_libs information,
> > but for building against shared libs you only need a subset. This
> > leads to having more build dependencies than neccessary in a
> > shared-libs only build. As a consequence some distributions decided to
> > remove all *.la files to keep build dependencies down. This is of
> > course not really a solution.
> 
> There is nothing you can do to reduce the number of build dependencies.
> If you can reduce it, there is a bug somewhere.

Let me clarify: I didn't mean the build dependencies for this library,
but for projects building on this library.

> However, you can reduce the number of depends of the package itself
> when linking shared.

That's what I meant.

> But recursivly, you'll still have the same dependencies.

Yes, but this only then applies for the runtime, e.g. when installing
the project depending on a lib, then all recursively dependent libs
are needed, but not for the build of the project itself.

> > Can this be somehow dealt with within libtool? It would need to
> > fork the semantics of dependency_libs into static vs shared libs
> > or something similar. I guess the difficult part is identifying
> > what parts of dependency_libs are needed for a shared build
> > against this library.
> 
> Debian has a patch that sets link_all_deplibs to no.  This basicly
> doesn't use dependency_libs for shared linking.

Hm, I had a quick look at that patch, looks very promising!

> Note that this causes various problems for which there are open bugs
> in the Debian bug tracking system.
> 
> Because of this, Debian is more and more moving from .la files to
> using pkg-config's .pc files, which contains the info we need, and
> also has cflags (-Is) in it.
> 
> If you need more info about this, please let me know.

Yes, please, especially what drawback this patch has, and why it isn't
accepted upstream.
-- 
Axel.Thimm at ATrpms.net

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