[QGIS-Developer] How to handle upstream Qt fixes

[Jürgen E. Fischer]

Hi Nyall,

On Fri, 03. Sep 2021 at 08:46:21 +1000, Nyall Dawson wrote:
> - KDE and other open source projects forked Qt 5.15 at
> https://invent.kde.org/qt/qt/qtbase/-/commits/dev/, and are actively
> backporting fixes from Qt6 to that branch. Fedora recently started
> using the KDE branch for Qt 5 library builds, so users of that
> platform once again are getting bug fixes deployed [1]. I'm unaware if
> other distributions or builds of Qt are using this currently.
> - Similarly, there's a KDE fork of Qt 3d at
>   https://invent.kde.org/qt/qt/qt3d/-/commits/kde/5.15/

I asked on #debian-qt-kde on OFTC and they are apparently not planning to apply
the patch collection blindly, but probably would apply individual patches (of
the currently 222 qtbase and 33 in qt3d patches) that we need.

> Right now, there's a number of very frustrating issues that Qt 5.15.2
> has which impact our users. An example is #44876, which results in
> very large PDF exports from QGIS with broken hairline line rendering
> [2].

Do you know whether the PDF issue is already addressed in the patch collection?


> - Are we free to change the Windows builds to use the KDE backports
> fork of 5.15 instead of the official 5.15.2 releases? (Or does that
> change lots of osgeo4w packaging things?). Similarly, are we free to
> move the MacOS builds to the KDE branch too?
> - Could we also move the Windows/MacOS builds of Qt 3d to use the KDE fork?

I suppose so - I would probably just apply them all in OSGeo4W and hope for the
best ;)


> - Does anyone know if Debian have plans to migrate to the KDE
>   backports fork? (Last I heard, the debian Qt maintainers stepped down
>   and the package is currently lacking a maintainer!)

see above.


> - If we can get the majority of our users onto builds which use the
>   KDE backports branch (i.e. Windows/mac users)

Do we know that there are significantly more users on Mac than on free
platforms?


>  , could we re-start the relationship with KDAB and contract them for bug
>  fixes again for 3.22?  (with the arrangement explicitly requiring them to
>  backport fixes to Qt 5 via KDE's fork).

I'd say yes.


Jürgen

-- 
Jürgen E. Fischer           norBIT GmbH             Tel. +49-4931-918175-31
Dipl.-Inf. (FH)             Rheinstraße 13          Fax. +49-4931-918175-50
Software Engineer           D-26506 Norden            https://www.norbit.de
QGIS release manager (PSC)  Germany                 IRC: jef on Libera|OFTC
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