RFC: Switching to min Qt version 5.14 for KF on December 14th

[Friedrich W. H. Kossebau]

Am Donnerstag, 17. Dezember 2020, 21:06:23 CET schrieb David Faure:
> In general I might have asked for a more conservative approach; but
> currently anything we do to help with preparing the Qt 6 migration is a
> good thing, and having one less Qt version to support helps with that.
> 
> So, in those exceptional circumstances, I'm in favour, go for it.

Okay :) And it are those exceptional circumstances also which made me push for 
the bump here, otherwise I would have rather tried to have us get Qt 5.13 back 
onto KDE CI.

Albert, commit data tells me did the last bump. Could you go and do the bump 
to Qt 5.14 as well now, given you seem to have some setup for that?

I already adapted the respective policy like this now, based on the discussion 
(please fix any issues directly on the page, linked below):
"
With Qt6 this changes a little bit again. We interpolate "as if" more Qt 5 
versions would be released:
* Qt 5.13 will be the minimum required version 6 months after Qt 5.15, i.e. on 
26 Nov 2020,
* Qt 5.14 would be the minimum required version 12 months after Qt 5.15, i.e. 
on 26 May 2021. With no-one known to stick with Qt 5.13 at the time, the date 
was moved to earlier mid-December 2020 (see discussion<link to ML thread>)
* Qt 5.15 LTS will be the minimum required version 18 months after its 
release, i.e. on 26 Nov 2021

The bumping of the minimum required version in the code is done at the begin 
of the release cycle of the next KF version affected, right after the release 
of the previous one.
"
* https://community.kde.org/Frameworks/Policies#Frameworks_Qt_requirements 

Going to Qt 5.14 also means a bump in supported compilers, see
    https://doc.qt.io/archives/qt-5.13/supported-platforms.html
vs.
    https://doc.qt.io/qt-5.14/supported-platforms.html

So at least GCC 4.8 -> GCC 5, MSVC 2015 as before.
Can anyone tell what the supported clang version of Qt 5.14 is? 


Volker, leaving the stage now for you and the considerations to update the 
plan for when Qt 5.15 should become the minimum dependency :)

Cheers
Friedrich