Can Plasma 5.9 depend on Qt 5.7

[Martin Graesslin]

On Tuesday, October 25, 2016 12:50:56 PM CEST Richard Brown wrote:
> Hi Martin,
> 
> The initial openSUSE view is as follows:
> 
> For openSUSE Leap, this decision will likely mean that we will have to
> remain with Qt 5.6 and Plasma 5.8 for the life of Leap 42.3 in order
> to preserve our stability expectations of our users.

Right. Using Qt 5.7 optionally would also not help you there as that would 
mean that features we advertised would not be available on openSUSE which 
would be bad from a communication point of view for both openSUSE and KDE.

> 
> As we discussed with you at oSC, Qt version jumps seem to bring a very
> high risk of breakages across a very broad scope, and I expect it
> would probably be too much of a risk to take in Leap 42.3.

understandable

> 
> Leap 42.3's release is currently expected Q3/4 2017

So in about a year. So that's two or three Plasma releases from now. I guess 
we would have the same discussion with every release then.

> 
> The expected lifecycle of Leap 42.3 would mean I'd expect it to be
> supported for ~18 months from that point.
> 
> This means in one way or another we'll have to find a way to support
> Plasma 5.8 until the middle of 2019
> 
> This is of course much longer than the currently announced lifecycle
> of Plasma 5.8, which I understand will end about the middle of 2018.
> 
> A 'year in the wilderness' is quite an uncomfortable situation for us
> to consider.

So about half a year more than currently planed. I guess that's doable. I 
assume that at that time all that matters are security fixes which we probably 
would do anyway for older releases (the last fix I backported even to 5.0). And 
you would have an updated frameworks and thus all the fixes coming from that.

> 
> We'd need to have a lot of discussions between our Release Team and
> KDE maintainers to figure out if we even have a feasible solution for
> coping with such a situation.

sure! Actually I don't see much difference on whether we depend on Qt 5.7 or 
not. I assume that even if we would  not raise Qt dependency Plasma 5.11 would 
not be useful for you as it would be not as long supported as Plasma 5.8.

So overall for openSUSE Leap the important question seems to be how to get 
Plasma 5.8 maintained half a year longer as currently planned upstream. I just 
assume that will be doable :-)

> 
> For openSUSE Tumbleweed, I imagine this presents no problem as we're
> already using Qt 5.7 there

yep.

> 
> Hope this helps,

Thanks for your feedback. Much appreciated that you communicate needs for your 
next year release that early.

Cheers
Martin

> 
> Richard
> 
> On 25 October 2016 at 08:16, Martin Graesslin <mgraesslin at kde.org> wrote:
> > Hi distributions,
> > 
> > the Plasma team would like to depend on Qt 5.7 for the next Plasma release
> > (5.9). Reasons are among others, that we would like to use:
> > * appmenu support
> > * QtVirtualKeyboard support
> > * QtQuickControls 2
> > 
> > Which are all new in Qt 5.7.
> > 
> > We would like to know whether that would cause a problem for any
> > distribution. Please remember that Plasma 5.8 is an LTS and will stay on
> > Qt 5.6.
> > 
> > Cheers
> > Martin

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