Re: [PATCH 1/1] curl: fix native dependency

[Qing He <qing.he@intel.com>]

On Mon, 2010-11-29 at 20:25 +0800, Richard Purdie wrote:
> On Sun, 2010-11-28 at 22:53 -0700, Chris Larson wrote:
> > On Sun, Nov 28, 2010 at 10:26 PM, Tian, Kevin <kevin.tian@intel.com> wrote:
> > > This also confuses me a bit. When virtclass-native is expanded, EXTRA_OECONF_append
> > > is simply a variable. In that case the expanded value should override the 1st assignment
> > > of EXTRA_OECONF_append, and then we should get:
> > >
> > > EXTRA_OECONF_append = " --without-gnutls "
> > >
> > > and then that's what we expect.
> > >
> > > I guess I may still overlook something here, and really appreciate your explanation
> > > on the whole flow which is helpful. :-)
> > 
> > No, EXTRA_OECONF_append is never a variable.  _append/_prepend are
> > operations, not part of the name.  The value gets set aside in a list
> > of appends for that variable.  One _append cannot override/replace
> > another on the same variable, its always cumulative.
> 
> Right.
> 
> Interestingly though, if I add this to curl*.bb:
> 
> FOO = "A"
> FOO_append = "B"
> FOO_append_virtclass-native = "C"
> 
> and then "bitbake curl-native -e | grep FOO" (he recipe has a
> BBCLASSEXTEND native) what should I see?
> 
> I see FOO = "AB" which is not what I thought it would do...

This is very interesting, I didn't see "AC" when preparing the patch
so went the other way. After seeing your experiment, I also tried this:

FOO = "A"
FOO_virtclass-native = "B"
FOO_virtclass-native_append = "C"

Then for curl-native, FOO = "BC", and there is an explicit variable
FOO_virtclass-native = "BC", this does not exist in RP's test.
So it's more clear to me now what "*_append is never a variable" means.


However, the gut feeling is that this construct introduces some
inconsistency. If "_append" is never a variable, but "_virtclass-native"
is, how is bitbake supposed to handle FOO_append_virtclass-native and
translate it into a FOO_virtclass-native variable?

To be more specific, if append is to be handled earlier than virtclass,
FOO may not be able to be evaluated at the time when append/prepend is
processed, as the following test case:

FOO = "A"
FOO_virtclass-native = "B"
FOO_append = "C"
FOO_append_virtclass-nativesdk = "D"

How should it be handled?

Thanks,
Qing