Re: [gentoo-dev] RFC: GTK USE flag situation (gtk, gtk2, gtk3; relevant to bug #420493)

[Gilles Dartiguelongue]

Thanks for attaching link to team's policy which tries to lift any kind
of ambiguities people may have for what concerns gnome team's packages,
I hope it proved useful in your discussions.


Le mercredi 12 février 2014 à 00:39 +0200, Alex Alexander a écrit :
> Hello fellow developers,
>
> In the first meeting of the new QA team, we discussed the state of the
> gtk{,2,3} USE flags in the main tree. [0]
>
> In its current state, USE="gtk" means gtk2. The Gnome team is trying to change
> this into "the most recent gtk version" (it is a work in progress).

Wrong, gtk USE flag means "enable gtk support", whether this is gtk 1, 2
or 3 depends on what the package (presumably library) supports and
whether is can be slotted or not and whether current gentoo maintainer
decides what can be reasonably supported.

> Unfortunately, the concurrent nature of gtk2/gtk3 has resulted in packages that
> may support either or both the toolkits. To handle this, a few developers have
> introduced the "gtk3" useflag, that prefers gtk3 over gtk2 when both toolkit
> versions are supported. At this point, the Gnome team highly recommends
> prefering gtk3 if possible, skipping the useflag altogether. [1]

Wrong, as is written in policy whether to prefer gtk2 or 3 is up to the
maintainer of the package. We point people to the fact that upstream
says gtk2 is a dead end and support will stop (if not in fact already
stopped) in the near future.

We also recommend to have maintainers support slots for their libs where
possible considering man-power and to only choose one toolkit for
applications considering where upstream development is going and
maturity of the port, and again, this is up to package maintainers.

> Some developers choose to follow the Gnome team's highlights, while others
> choose to go their own way. The QA team would like to establish a guideline
> that solves this problem in the best way possible.
>
> During our discussion, it was pointed out that keeping a generic USE="gtk" is
> sub-optimal. The non-straightforward nature of new toolkit versions makes
> transitioning from one to the other a slow, tedius process and we think that a
> non-versioned USE flag makes things even worse.
>
> A few of our members recommended a move away from the unversioned USE="gtk" to
> versioned-only USE flags. Qt managed to do this quite successfully when they
> transitioned from the unversioned USE="qt" (that actually meant qt3) to
> USE="qt4". The benefits can be seen now that qt5 is around the corner.
> USE="qt5" is straightforward, does not mess with qt4 packages and was
> introduced to the tree without messing with current packages too much - other
> than adding a new use flag where appropriate. There is also no need for
> USE="qt" anymore.
>
> To achieve this, version 3 of gtk should always be enabled by USE="gtk3". At
> some point in the future, when gtk2 consumers reach zero, we will retire "gtk"
> for good. Then, if some day gtk4 comes around, we will be able to introduce
> support for it in the tree by simply adding USE="gtk4", without having to
> re-structure half the tree.
>
> We are reaching out to the developer community to hear your thoughts and ideas
> on the matter. We would like to reach a decision that could possibly affect and
> direct the state of whole tree. This decision could then be turned into a
> policy, improving Gentoo's consistency across the tree.

Imho the whole discussion stems for packages maintainers which, as you
have written, did not follow our recommendation and tried to provided
application with both gtk2 and gtk3 support.

I agree that "Gentoo is about choice..." however as a maintainer of a
lot of packages, it is unreasonable to try to support two configuration
where one is dying slowly due to upstream (gtk)  maintainer focus being
elsewhere, hence why we wanted maintainers to choose. Instead, it occurs
that some decided not to choose or to stop users from annoying them with
100 of duplicate bugs about not providing the alternative.

Looking at the situation from a gnome team member perspective when Gnome
3 was introduced to the tree, only three packages (providing libs)
needed exception to the rule to avoid unreasonable maintenance overhead:
spice, gtk-vnc and avahi. All of them had proper USE-dependencies in
relevant ebuilds so no confusion would be possible.

Right now, I don't really get the point of this discussion given all the
precedent threads about this, be it 2 years ago and 8-10 years ago.

Anyway, if QA would provide with a list of "offenders" (this could have
been done on bugzilla btw), we could walk-through the list and verify
what/if/how packages would need extra USE flags or not and not just for
our self-written policy's sake that is.

> Cheers
>
> [0] https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Meeting_Summaries#Summary_of_Wednesday_January_29.2C_2014
> [1] https://wiki.gentoo.org/wiki/Gnome_Team_Policies#gtk3

-- 
Gilles Dartiguelongue <eva@g.o>
Gentoo