Re: [gentoo-dev] crossdev: installing _host_ build dependencies not automatic?

[James Le Cuirot <chewi@gentoo.org>]

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On Wed, 3 May 2017 17:56:43 +0200
Alexis Ballier <aballier@gentoo.org> wrote:

> On Wed, 3 May 2017 12:05:48 +0200
> "Paweł Hajdan, Jr." <phajdan.jr@gentoo.org> wrote:
> 
> > I encountered <https://bugs.gentoo.org/show_bug.cgi?id=617276> while
> > working on some cross-compiling project.
> > 
> > Admittedly, it may not be that easy to handle host package
> > dependencies fully automatically.
> > 
> > I'm wondering - is it documented what portage guarantees, and what I'm
> > expected to just manually handle to provide host build dependencies?
> > 
> > Any other advice about properly using crossdev would also be
> > appreciated. I'd be happy to test and help improve things.  
> 
> 
> From man emerge:
> 
> 
>        --root-deps[=rdeps]
>               If  no argument is given then build-time dependencies of
>        packages for ROOT are installed to ROOT instead of /.  If the
>        rdeps argument is given then discard all build-time dependencies
>        of packages for ROOT.  This option is only meaningful when used
>        together with ROOT and it should not be enabled under normal
>        circumstances!
> 
>               Does not affect EAPIs that support HDEPEND.  Experimental
>               EAPI 5-hdepend provides HDEPEND as a new means to adjust
>               installation into "/" and ROOT.  If ebuilds using EAPIs
>               which do not support HDEPEND are built  in  the same
>               emerge run as those using EAPIs which do support HDEPEND,
>               this option affects only the former.
> 
> 
> crossdev wrappers set --root-deps=rdeps (read cross-emerge, this can be
> overriden), but be careful: If you only care about getting all the deps
> and maybe more then removing --root-deps might help you. However, when
> cross compiling you will likely run into broken deps since / and ROOT
> will not use the same keyword visibility.

I was going to point to crossdev's use of --root-deps=rdeps too. I did
wonder why on earth this was even added. I overrode it for quite a
while and didn't have any issue. History showed that it was added by
solar without much of an explanation. He's no longer around to ask. It
wasn't until I tried to build a brand new ppc64le system recently that
I finally found a reason for it, though I'm not sure it was the
original reason. The multilib ABI USE flags start conflicting horribly
in cross situations and this option seems to be the only way around it
at present.

I doubt keyword visibility is an issue. Portage uses a different
configuration between / and ROOT when cross-compiling. I don't think it
tries to force the same package versions beyond what is specified in
the ebuild. For pure build-time dependencies, the package will only be
installed to / anyway (i.e. you don't need cmake in ROOT) so there is
nothing to enforce here.

-- 
James Le Cuirot (chewi)
Gentoo Linux Developer

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