Re: [gentoo-dev] [RFC] gtk/gtk2/gtk3 USE flag situation

[Mart Raudsepp]

Ühel kenal päeval, R, 27.05.2016 kell 13:14, kirjutas Anthony G.
Basile:
> On 5/27/16 12:59 PM, rindeal wrote:
> > On 27 May 2016 at 18:54, landis blackwell <blackwelllandis@×××××.co
> > m> wrote:
> > > I stopped reading after you reminded me it was 2016
> >
> > Good to know, thanks for stopping by.
> >
>
> Yeah the "its <current> year" meme has been making its rounds of the
> internet.
>
> anyhow, my 2017 question is about avahi.  right now i have USE=gtk
> and
> gtk3, where gtk really means gtk2.  i'm not going to change that
> because
> it fits QA's specs.  but i could remove it altogether and just drop
> gtk2
> support for the next release.  good idea?  bad idea?  i guess i'm
> asking
> whats the status of gtk2 in gentoo seeing as its dead upstream.

I don't see a strong reason to have gtk2 support if there are no gtk2
consumers remaining in the tree. I somehow doubt that's the case for
avahi, though?
If gtk2 support is removed though, then per gnome policy gtk3 component
should come with USE=gtk and per QA policy USE=gtk3.

The QA policy is not finalized and completely contradicts our side of
things, hence discussions are needed, but did not conclude.
This is a thread to continue this discussion, I suppose.

I wouldn't change anything till then really, especially for libraries,
where it's mostly handled by USE depends anyway.

One thing is USE flag naming for gtk2 and gtk3, another thing is if
apps should provide support on building against either.
I strongly disagree with using the same flag names for "provide gtk2
linking higher level library" and "Build this GUI application against
gtk version 2". QA proposed policy has this regression.
Also for libraries it is a "either or both" situation, for apps it's a
"one or the other" situation. This gets awful very quick if any
application maintainer decides to express it with a
REQUIRED_USE="^^ ( gtk2 gtk3 )", combined with the libraries in tree
that then would have REQUIRED_USE="|| ( gtk2 gtk3 )" + libraries in
tree where gtk component is optional, and if available both gtk2 and
gtk3 versions are available with
REQUIRED_USE="gtk? ( || ( gtk2 gtk3 ))".

This would be clean with only libraries using gtk2/gtk3 as is GNOME
teams current policy. Then the natural thing would be to have a
different USE flag to mean to prefer gtk2 for user facing applications
when possible instead of gtk3 (USE="force-gtk2" being suggested here
for that)
With this approach we can cleanly handle any upcoming gtk4 as well,
while naturally moving users who don't care into using the latest
version.

I also strongly believe that USE flags should be first and foremost
about features, not an expression of the name of an external
dependency.

Gilles did a huge start of work on mapping gtk* use flag usages in a
spreadsheet, but given the volume, got distracted before finished.
I pointed this out to the QA team to look at, but have not heard
anything back.
The point of the exercise was, that it turns out half of the tree seem
to mis-use USE=gtk in some way, and QA should really concentrate on
helping with that first. Then the situation would be much clearer, as
there wouldn't be all that many USE=gtk's remaining.
Anyhow, this is where the discussions stalled last time around.

I think we should first figure out about the USE flag usages (naming +
library only or not).
We can bikeshed if gtk2 version for applications should be provided
more liberally in addition to gtk3 as a one or the other choice later
on. I don't feel too strongly about making that hard if it doesn't step
on our library USE flag namespace.


Mart