Bug#976603: Droping fcitx4/5 coexistence (Was: Bug#976603: Icon themes in breeze and papirus are not supported)

[Boyuan Yang <byang@debian.org>]

Hi,

在 2021-11-23星期二的 00:15 +0100，Gunnar Hjalmarsson写道：
> Hi!
> 
> >      + debian/control: Let fcitx5 conflicts with:
> >        - fcitx (<< 1:5)
> >        - fcitx-data (<< 1:5)
> >        - fcitx-bin (<< 1:5)
> 
> That may become a bit problematic with respect to package upgrades for 
> users who have both fcitx and fcitx5 installed. I suppose that fcitx5 
> upgrades will be held back if you just do "apt upgrade".
> 
> Ubuntu Kylin 21.10 includes both fcitx and fcitx5 by default. The 21.10 
> -> 22.04 release upgrade is not so far away.
> 
> Not sure what to suggest. To start with I wonder if you have considered 
> situations like the one I mentioned.

This is tough decision with no ideal solution. From fcitx upstream's
perspective, the upstream has no intention to support coexisted fcitx4/fcitx5
from the very beginning, and co-installation provides little (if not zero)
benefit. Besides, fcitx5 will likely eventually replace fcitx4.

>From distribution's perspective, Debian included Debian-specific patch to
allow coexistence in the initial fcitx5 packaging. This introduced inherent
bug on icon handling, which I would like to solve recently. Now, I wouldn't
say trading co-installation possibility for bug-free icon handling is always
beneficial, but it shouldn't bother users with reasonable setup.

>From packaging perspective, versioned conflicts are indeed a little bit too
aggressive. I was indeed not aware of Ubuntu Kylin's condition of installing
both fcitx and fcitx5 by default. This is a weird decision with no benefit: th
e out-of-box experience won't benefit from co-installation.

Anyway, the correctness of default co-installation decision is out of current
discussion scope. Personally (as packager of fcitx) I do not wish to keep
carrying debian-specific coexistence patch forever, but I would be happy to
work with any team from Ubuntu on securing a solid Ubuntu 22.04 LTS.

The path forward really depends on which fcitx does Ubuntu(-any-flavor) plan
to ship by default: fcitx4 or fcitx5. I would be surprised if they still wish
to install both by default in future, but please let me know if this would be
their decision.

For distribution upgrade: I remember that Ubuntu handles it with do-release-
upgrade. Even for Debian, we do not instruct users to only run "apt upgrade"
across major version upgrades: users always invoke "apt full-upgrade/apt dist-
upgrade", so this shouldn't be a problem. Just make sure that the metapackage
for default Ubuntu desktop depends on correct fcitx (4 or 5, depending on
final decision for 22.04 release).

I may postpone the removal of conexistence patch (with buggy icon handling)
till after Ubuntu 22.04 freeze, but this will happen sonner or later. Please
let me know if there are more information available.

Thanks,
Boyuan Yang