[QGIS-Developer] FYI: Qt LTS Releases To Be Restricted To Commercial Customers

[Even Rouault]

On lundi 27 janvier 2020 17:35:22 CET Paolo Cavallini wrote:
> Thanks Even. As I read it, this essentially means we are more or less
> forced to use the latest version, not the LTS (or to stick to an older
> one). This could mean more bugs.

QGIS sources aren't bound to a particular QT version. Currently the requirement is just >= 5.9
So pretty much depends on what binary distributions actually ship.

I've tried to follow the discussion on the thread announcing it at
https://lists.qt-project.org/pipermail/development/2020-January/thread.html#38316
but it is still unclear if QT Company will publish the source of their LTS branches or not.
At the very least, bugfixes that apply to the latest -dev branch, and older branches,
will be available, so people can *potentially* backport them (pending extra burden for
FOSS QT, typically Linux ones, distribution maintainers to scrutanize what must be
backported, which according to [1] would be very hard to do). If they don't publish the
source of the LTS branches, and a bug only affects a LTS branch and not the latest -dev branch, then
non-commercial customers will not benefit from it.

A lot of speculations in the above thoughts, and from a outsider of the working of the QT
project. If QT Company has the ultimate say to which branches are maintained or not,
or if other companies might jump in to bring back public LTS support...

Anyway, somewhat related to the above considerations, it looks like as far as OSGeo4W is
concerned, there's a QT 5.11.3 release with security fixes (cf [2]) whereas 5.11.2 is shipped now.
But as the 5.11 branch is no maintained anymore, it is
well possible that 5.11.3 contains know issues, including security related ones,
fixed in later versions.
The 5.12 series is (should we say "was" now ?) announced as the LTS one with support until
5.12.2021 according to [3], so could be (have been?) a good candidate to track.
Perhaps some upgrade policy should be defined (only makes sense if there's manpower to
implement it of course)

Even

[1] https://lists.qt-project.org/pipermail/development/2020-January/038388.html
[2] https://www.qt.io/blog/2018/12/04/qt-5-11-3-released-important-security-updates
[3] https://en.wikipedia.org/wiki/Qt_version_history

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