[OE-core] RDEPENDS_${PN} and virtclass-native

[Chris Larson]

On Wed, May 25, 2011 at 5:00 PM, Richard Purdie
<richard.purdie at linuxfoundation.org> wrote:
> On Thu, 2011-05-26 at 00:02 +0100, Richard Purdie wrote:
>> I think we need to fix native.bbclass. I dread to think what this is
>> doing to the dependency tree at present. We did remove most references
>> to RDEPENDS directly so I think that makes this a high priority to fix.
>>
>> I'd note that the rewriting code is fraught with ordering/expansion
>> issues which is why that code plays games with the variables like it
>> does.
>>
>> DEPENDS is horrible and it looks like we needed to do something similar
>> for RDEPENDS. Better solutions to the ordering problems would be very
>> welcome. It problem was the use of DEPENDS_prepend in places iirc.
>
> I just reminded myself of the problem with DEPENDS.
>
> Imagine the recipe says:
>
> DEPENDS = "foo"
> inherit autotools
>
> Behind the scenes, autotools (amongst other thinsg) does a:
>
> DEPENDS_prepend = "autoconf-native"
>
> The trouble comes when you try:
>
> DEPENDS_virtclass-native = ""
>
> since you want to drop the foo dependency. The dependencies being added
> by autotools.bbclass are still wanted but they get overwritten. At this
> point I had to remember bitbake's finalize ordering. It does:
>
> finalize()
> <call anonymous python>
> finalize()
>
> The first call to finalize() expands the _prepend/_append before we see
> them. We then lose the ability to see what was added though the classes
> vs. what was in the recipe. The second finalize can then only clobber
> the data.
>
> If we could get our function called before the first finalize(), we
> would remove the need to play the games we do which is looking very very
> attractive.
>
> I suspect its time to extend the anonymous python to indicate more
> specifically when it would like to be run...

Just need to add another event at the appropriate place. I wonder
where RecipeParsed fits into that ordering.
-- 
Christopher Larson
clarson at kergoth dot com
Founder - BitBake, OpenEmbedded, OpenZaurus
Maintainer - Tslib
Senior Software Engineer, Mentor Graphics