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

[landis blackwell]

I stopped reading after you reminded me it was 2016
On May 27, 2016 9:21 AM, "Mart Raudsepp" <leio@g.o> wrote:

> Hello,
>
> Despite it being 2016 and gtk2 pretty much dead, buried and forgotten
> upstream, many applications still support only gtk2, have subtle issues
> with their gtk3 port, or support both, with some of our userbase
> clinging to gtk2 for dubious political or aesthetical reasons.
>
> For the latter cases, despite GNOME teams policy and strong preference
> on not providing a choice and just choosing gtk2 or gtk3 (gtk3 if it's
> working as good as gtk2), some cases exist where the maintainers want
> to provide such choice. In some cases it is understandable for a short
> while during transition, e.g firefox. In other cases, it is purely for
> the sake of providing the choice of working with a deprecated toolkit,
> apparently.
>
> My highly biased essay aside, we need to finally globally agree on what
> we do in this situation. If we allow this choice at all, only for
> special cases, or widespread. And if this choice is provided, how do we
> name the USE flag.
>
> Historically, for very good reasons in past and present GNOME team
> members opinion, USE=gtk has always meant to mean to provide support
> for gtk in general, not any particular version. This is opposite to
> what the Qt team has been doing.
> In our opinion, in a perfect world, only USE=gtk would exist, and no
> USE=gtk2 or USE=gtk3 would be necessary. But as we don't live in a
> perfect world, we have made use of USE=gtk3 for providing gtk3 support
> from library packages to mean to build gtk3 support. Sadly that
> overloads USE=gtk in many cases to then mean to build gtk2 support.
> This would ideally not be needed, as the package would instead be
> slotted and parallel installable for gtk2 and gtk3, which should be
> theoretically possible in all cases, because gtk2 and gtk3 may not live
> in the same process, so not the same library either.
> Due to some packages needing too much manpower effort to do such a
> split, USE flags are used in such a case.
> Good examples of such slot splits existing are for example the
> libappindicator stack. This used to be the case with almost all GNOME
> libraries as well, but most of them only provide gtk3 now, as gtk2 is,
> well, dead.
> Bad examples would be e.g avahi and gtk-vnc, which deemed too hard to
> split up into separate SLOTs. In some cases it might have been meant as
> a transitional thing, until all consumers are ported to gtk3, but it
> has been lingering on due to consumer apps not being ported or we
> haven't yet noticed to remove the gtk2 support in the library package.
>
> Now these are libraries, and despite some USE flag confusion, it's not
> a huge issue, because consumers are USE depending on what is required.
> This all is written out in
> https://wiki.gentoo.org/wiki/Project:GNOME/Gnome_Team_Ebuild_Policies#gtk3
> since the GNOME project pages moving to wiki, and also long before that
> in GuideXML era, and we've pointed people towards that.
>
> And then we have applications that support building against either gtk2
> or gtk3.
> In most cases, any requests to provide the choice to have an
> application use gtk2 instead of gtk3 gets instantly marked as duplicate
> of https://bugs.gentoo.org/374057 but in some cases the maintainer has
> chosen to provide this choice for now, and here is the problem - we
> don't really have a good agreed on way to name such a choice in USE
> flags, if we should provide such a choice at all.
>
> USE=gtk2 is not good, due to the confusion issues with USE=gtk3 and
> USE=gtk and it being problematic. The GNOME team shall probably veto
> such USE flag usage if we are deemed to have such an authority as gtk+
> maintainers, unless we rework it all in expectations of gtk2 corpse
> being carried around for a decade as well... I have quite a few bugs
> against packages to file already for this, afair.
>
> I kind of like what firefox did there, going in the spirit of the
> force-openrc flag we have for avoiding systemd dependency, even if it
> currently means worse user experience. So if we provide such a choice
> for apps at all, I might agree to USE=force-gtk2 for this for apps. And
> we would like to eventually (or immediately) p.use.mask this and once
> it's 2017 and gtk2 truly dead and buried and full of known security
> holes, get rid of it again.
> But this highlighted the inconsistency we are having, ending up with QA
> initiated bug https://bugs.gentoo.org/581662
>
> tl;dr and my proposal would be the following:
>
> * USE=gtk means providing support for GTK+; because we don't have a
> USE=gui, this also means "provide a GUI version built on top of gtk+"
> for packages where a GUI is optional.
>
> * USE=gtk3 may be used only for controlling extra libraries to be
> shipped for gtk3 support (the extra library file will link to gtk3),
> _in addition_ to gtk2 version. This is a temporarily measure until gtk2
> support can be dropped and it will only ship gtk3 version of the
> library. This gives a flag to be able to USE depend on by gtk3 apps.
> This leaves the question about the opposite open, however. This is why
> USE=gtk2 would be bad for apps, maybe we need to use it for this
> library case, when gtk3 version is primary and we just have 1 app
> remaining that needs the gtk2 version or something.
> The concept of library is broad here, covering also gtk theme engines
> (x11-themes/gtk-engine-*, but they shouldn't be hard to split) and
> modules (e.g caribou, libcanberra)
>
> * Applications may only use a gtk2 based stack or gtk3 based stack in a
> given version/revision. gtk3 is strongly preferred when it is deemed to
> not have any regressions compared to gtk2 build, but the choice is
> ultimately with the maintainer. Once the application converts to using
> gtk3 in our distribution, it should try hard to stay that way in
> upcoming versions as well.
>
> * Some exceptions to the above may exist under heavy consideration,
> especially in cases where the toolkit usage is complex and may have
> some issues for some, but in general gtk3 support is deemed good by
> upstream. Most notable here would be browsers like firefox and
> chromium, which are using gtk dependency more for emulating the theme
> it uses, rather than using it as its real toolkit. If such exceptions
> are allowed, the USE flag naming here must be consistent amongst the
> exceptions. My proposal would be USE=force-gtk2 then, as I have no
> better ideas without stomping on the USE=gtk{2,3} historical meaning.
>
>
> When arguing in favor of supporting gtk2 builds more for apps, please
> do keep in mind that gtk2 really is pretty much dead. And no, MATE,
> XFCE and others are NOT continuing its support; they are just slow in
> fully converting to gtk3, but they are doing so and I expect both of
> those to be fully done this year, around autumn.
> If the issue is political or just a general gnome3 or gtk3 hate, then I
> would ask you to keep your political opinions or hate outside this
> thread and go contemplate on more important life issues.
> If the issue is lack of themes, then I would like you to help package
> more gtk3 themes. gtk3.20 now has a stable CSS based theme API and
> themes shouldn't be breaking anymore beyond this point, theoretically.
> And gtk3 theme packages should pretty much just be CSS files and some
> metadata. Though we have yet to get over that bumpy thing yet (a main
> reason gtk3.20 isn't in main tree yet).
>
> Thoughts? Agreements? Suggestions?
> I'm particularly interested in QA opinion here. I believe WilliamH
> wanted to spearhead this from their side.
>
>
> Regards,
> Mart Raudsepp
> Gentoo developer, GNOME team
>
>