Re: [gentoo-dev] Needs ideas: Upcoming circular dependency: expat <> CMake

[Rich Freeman <rich0@gentoo.org>]

On Fri, Dec 20, 2019 at 8:41 AM Gerion Entrup <gerion.entrup@flump.de> wrote:
>
> Am Donnerstag, 19. Dezember 2019, 19:43:37 CET schrieb Sebastian Pipping:
> > On 19.12.19 18:37, Michał Górny wrote:
> > > We have a better alternative that lets us limit the impact on the users.
> > > Why not use it?
> >
> > Which one?  The CMake bootstrap copy?  The adding to stage3 one?
>
> If an error message can be shown, maybe this is enough as a hint:
> "expat and cmake have circular dependencies. Emerge it the first time with:
> USE=bundled-cmake emerge -1 cmake expat
> and then just don't care anymore about this use flag."
>

Not sure about custom error messages but in any case when using that
bundled-cmake USE flag it would probably make sense to do an ewarn
that the bundling took place and is only intended for temporary use,
and that the package should be re-merged without the flag once expat
is working.  That would also cover users who inadvertently set the
flag.

I think that bundled-cmake also might make more sense than
system-cmake, even though the latter is more established.  We have a
lot of users who set USE=-* and that means they're going to end up
with lots of stuff bundled that doesn't need to be.  I'm no fan of
USE=-* in general but it seems like we should try to avoid making not
setting a USE flag the less secure option since it does happen a lot.

I'm just commenting on the USE-based solution.  The compat package
solution obviously bypasses this particular problem entirely.

-- 
Rich