Re: [gentoo-dev] Reminder on dependencies.

[Thomas de Grenier de Latour <degrenier@easyconnect.fr>]

On Mon, 24 Oct 2005 21:37:03 -0700
Donnie Berkholz <spyderous@gentoo.org> wrote:

> The consequences of the two sides are like this, from what I can
> see:
>
> 1) Headers are run-time and build-time deps
> 2) Headers are build-time deps only

Imho, that case fall under the concept of "exported deps" i had
proposed some time ago, here:
http://thread.gmane.org/gmane.linux.gentoo.portage.devel/750

Quickly summarized, the idea (for RDEPEND) was, for instance, the
following:
- pkgA installs libA.so, and depending on USE flag "flagB", it's
libA.la file may contain "-lB".
- thus, a pkgC linked to libA may also be linked to libB, but that
depends on USE flags of pkgA, which can't be taken into account in
pkgC's RDEPEND. In such cases, one simply can't write correct
RDEPEND for pkgC.
- the proposed solution was that pkgA.ebuild declares a
EXPORTED_RDEPEND="flagB? ( pkgB )" variable. Evaluation of this
variable ("pkgB" or empty, depending on whether flagB was set at
pkgA compile time) would be stored in pkgA vardb metadatas, and
packages RDEPENDing on pkgA would also automatically include this
result in there RDEPENDs. Thus, pkgC would get correct RDEPENDs,
depending how pkgA was compiled.

Sure, the idea also applies for DEPEND (didn't talk about it in my
initial RFC, but that's required anyway for the above example with
libs explicitly linked through .la files). In the case of "headers
including other headers", it would be as follow:
 - pkgA installs headerA.h, which has an "#include <headerB.h>"
 - since pkgA's binaries/libs don't need pkgB at runtime, it doesn't
have an RDEPEND on this pkgB. But it should EXPORT_DEPEND="pkgB".
 - pkgC, which has a DEPEND="pkgA", would then automatically import
a DEPEND on pkgB.

Now, that's just a vague idea of portage improvement. Not sure how
good/bad it is, but anyway it's not something that would be
available anytime soon. And until something like that is possible,
i tend to agree Spider that cluttering RDEPENDs is the less worst
one can do to make things work.

--
TGL.

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