Would distributions have an issue if KF 5.77+ would require Qt >= 5.14 (instead of >= 5.13 as of now)?

[Aleix Pol]

On Tue, Dec 1, 2020 at 1:30 PM Jonathan Riddell <jr at jriddell.org> wrote:
>
> Not from KDE neon of course, we're on 5.15.  And not from the KDE snaps build either.  But I suppose there's more than just Linux distros to consider as we ship apps using KDE frameworks on Flatpak, Android, Windows, even Mac to ponder too.
>
> Jonathan
>
>
> On Tue, 1 Dec 2020 at 12:14, Friedrich W. H. Kossebau <kossebau at kde.org> wrote:
>>
>> Hi,
>>
>> last week KDE Frameworks master saw a bump in the required/expected minimal Qt
>> version to Qt 5.13, following rules once agreed and noted here:
>> https://community.kde.org/Frameworks/Policies#Frameworks_Qt_requirements
>>
>> I would like to challenge that former decision though and propose to instead
>> go straight to Qt 5.14 as minimum requirement now.
>>
>>
>> QUESTION:
>> Would any of the distributions have an issue with requiring Qt 5.14 instead of
>> Qt 5.13?
>>
>>
>> From some quick checks using https://repology.org/ it seems that any
>> distribution versions which currently use Qt 5.13 have also settled on some
>> older KF version, so will not update to just KF 5.77 and thus be screwed.
>>
>> Motivation:
>> * KDE CI not setup ATM to cover builds with Qt 5.13 (no build, no unit tests)
>> * Qt 5.14 added some new API, chance to miss out when using that in new code
>> * C++: no need to write #if QT_VERSION < QT_VERSION_CHECK(5, 14, 0) variants
>> * QML: no need to do hard-to-read generation tricks to support < Qt 5.14
>> * Qt 5.13 went out-of-support in June
>> * App bundle builders would rather use some recent Qt 5.14/5.15
>>
>> So by restraining to Qt 5.13 as minimum version IMHO we would make/keep life
>> complicated for KF contributors without adding any value for anyone.
>>
>> With most of KDE Frameworks in my local checkout:
>>     grep "QT_VERSION_CHECK(5, 14, 0)"  frameworks/*/src -r 2>/dev/null | \
>>         grep "QT_VERSION " | wc -l
>> gives me "92", so there are quite some code variants which need support in
>> current code.
>>
>> From the emails at least in https://mail.kde.org/pipermail/kde-frameworks-devel/2020-July/112712.html I could not see a discussion whether Qt 5.13 makes
>> sense at all now, seems mainly the algorithm was applied. I propose to match
>> the result to known real world needs now. Or teach me what I have missed here
>> :)
>>
>> Cheers
>> Friedrich

For Flatpak it's not a problem either, We've had 5.15 for a while.

Any distro shipping 5.13 right now (and 5.14 in 9 days) is doing a
disservice to its users anyway, since upstream isn't supporting it
either.
https://en.wikipedia.org/wiki/Qt_version_history#Qt_5

Aleix