[Buildroot] [PATCH] core/pkg-infra: really build all dependencies of foo with foo-depends

[Yann E. MORIN <yann.morin.1998@free.fr>]

Arnout, All,

On 2019-07-03 23:28 +0200, Arnout Vandecappelle spake thusly:
> On 02/07/2019 22:12, Yann E. MORIN wrote:
> > Currently, foo-depends only builds build dependencies. This means that
> > download and extract dependencies are not built.
>  But also patch dependencies.
> 
>  Patch dependencies are special, because when used normally, they cause the
> following chain (I'm simplifying, obviously):
> 
> FOO_PATCH_DEPENDENCIES = bar
> foo-patch: bar-patch
> 
> while for all other types of dependencies it would be:
> 
> FOO_EXTRACT_DEPENDENCIES = bar
> foo-extract: bar
> 
>  So, this patch can lead to circular dependencies, because bar could in turn
> depend on foo (that's precisely why this construct was introduced).

Ah, but no, the _PATCH_DEPENDENCIES were not introduced _precisely_ to
allow the inverse _DEPENDENCIES.

_PATCH_DEPENDENCIES were introduced to ensure a package is extracted
before another is patched.

That it allowed for inverted _DEPENDENCIES is totally happenstance. And
I think it was a mistake to not forbid that situation.

>  However, it turns out that we only use this _PATCH_DEPENDENCIES for Linux
> extensions.

And linux-tools.

> In addition, most of them don't even depend back on linux. The only
> one in that situation is RTAI. And even for that case, it's not really a
> circular dependency. Instead, you have:
> 
> linux-depends: rtai <other linux deps>
> rtai: ... linux ...
> linux: linux-install
> linux-install: linux-build
> linux-build: linux-configure
> linux-configure: linux-patch <other linux deps>
> linux-patch: linux-extract rtai-patch
> linux-extract: linux-source
> 
> So, not an actual circular dependency, because 'linux-depends' is not a target
> that is used internally.
> 
>  Therefore, I've applied to master, thanks.
> 
>  I probably should have added the above explanation to the commit message :-(

Well, thanks for the heads-up on this. I was not even expecting it to be
applied so fast, in fact, given the potential for breakage! ;-)

Regards,
Yann E. MORIN.

>  Regards,
>  Arnout
> 
> 
> > First, but a minor point, this is inconsistent with foo-show-depends,
> > which does display all dependencies:
> > 
> >     $ make host-gzip-show-depends
> >     host-skeleton host-tar
> >     $ make host-gzip-depends
> >         # Only host-skeleton is built and installed
> > 
> > Second, and more important, it makes it more difficult to preapre a
> > debug build, like so:
> > 
> >     $ make foo-depends
> >     $ tar cf output.tar output
> >     $ make foo
> >         # bummer, broken
> >         # edit foo.mk to try and fix it
> >     $ rm -rf output; tar xf output.tar
> >         # rince and repeat
> > 
> > Change foo-depends so that it really builds all the dependencies for
> > foo, bringing it on-par with foo-show-depends.
> > 
> > Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
> > Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> > ---
> >  package/pkg-generic.mk | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/package/pkg-generic.mk b/package/pkg-generic.mk
> > index b00967c648..9620dec524 100644
> > --- a/package/pkg-generic.mk
> > +++ b/package/pkg-generic.mk
> > @@ -801,7 +801,7 @@ $(1)-extract:			$$($(2)_TARGET_EXTRACT)
> >  $$($(2)_TARGET_EXTRACT):	$$($(2)_TARGET_SOURCE)
> >  $$($(2)_TARGET_EXTRACT): | $$($(2)_FINAL_EXTRACT_DEPENDENCIES)
> >  
> > -$(1)-depends:		$$($(2)_FINAL_DEPENDENCIES)
> > +$(1)-depends:		$$($(2)_FINAL_ALL_DEPENDENCIES)
> >  
> >  $(1)-source:		$$($(2)_TARGET_SOURCE)
> >  $$($(2)_TARGET_SOURCE): | $$($(2)_FINAL_DOWNLOAD_DEPENDENCIES)
> > 

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