[LyX/ next] Prepare the removal of Python 2 support

[Pavel Sanda]

On Fri, May 31, 2024 at 01:51:31AM +0100, José Matos wrote:
> On Fri, 2024-05-31 at 00:02 +0200, Pavel Sanda wrote:
> > The research which should be done is to pair aprox. versions
> > of Qt, gcc & python in some still alive oold LTS ubuntu/redhat + 2.5
> > years.
> > It does not make sense to invest time for supporting old gcc when
> > the rest won't work anyway.
> > 
> > I did not do this research yet, but the quick check on my terminal
> > showed 3.9.2 and I'm not even running old LTS, so my first guess is
> > that you are trying to bump too much...
> > 
> > Pavel
> 
> The current Ubuntu LTS é 24.04, the previous one is Ubuntu 22.04 LTS
> jammy. In the oldest version the Python version that comes with the
> system is 3.10.4.

By *old* LTS I meant something like 16.04/18.04.

> In October of 2026 Python 3.10 will no longer be supported even in
> terms of security releases:

Sure, but LTS distros tend to have independent stream of important security
patches even when upstream stopped the support.

> On the other hand if you want to build for older systems it is possible
> to use new tools to build and run.

I am hesitant to push users for tinkering with python installs just to run lyx.


Anyway, my breakdown would be:

LyX 2.4 requires GCC 4.9, Python 2.7/3.5, Qt 5.4 (>=5.6 suggested)

This is what I see wrt ubuntu:
focal/20.04 (sec support till 2030): GCC 9.3, Qt 5.12, Python 3.8.2
Older do not ship python 3 / Qt 5, end of story.

Redhat world:
RHEL 7 is dead, Searching RHEL 8 (sec support till 2029) packages seems
behind redhats login wall but when I look on pkgs.org (sorry if I mess up,
not expert in redhats ecosystem) I see GCC 8.5, Qt 5.15, I don't see python3 
packages, but when login on nearby rocky 8.9 machine I see:
$ python3 --version
Python 3.6.8


The lower intersection gives GCC 8.5, Qt 5.12, Python 3.6, if, as you say,
is easy to update python3 in rhel, maybe 3.8 then.

All in all, if we have incentive, we could bump some deps for master
right away, kill python 2.7, but python 3.10 seems premature for 
lyx 2.5 in my opinion.

As said it will break even on machine I am still using for active
development and that system did not even switch to LTS (yet :).
Not a good sign...

Pavel