Bug 619722 – [qt overlay] plasmashell 5.9.5 / 5.9.95 / git master crashes with Qt 5.9

• Product: Gentoo Linux
• Status: RESOLVED UPSTREAM

[Description Matthias Dahl 2017-05-26 07:48:25 UTC]

Created attachment 474350 [details]
plasmashell crash backtrace

Starting with Qt 5.9, plasmashell 5.9.5 / 5.9.95 / git master crashes. I am not yet convinced this is a Qt and/or KDE issue, so it could also be related to the Gentoo split builds somehow.

Nevertheless, I opened a bug upstream, since I am somewhat at my wit's end:
https://bugs.kde.org/show_bug.cgi?id=380219

I will attach a backtrace of my crash as well as the mandatory "emerge --info".

[Comment 1 Matthias Dahl 2017-05-26 07:50:07 UTC]

Created attachment 474352 [details]
emerge --info

[Comment 2 Andreas Sturmlechner 2017-05-26 15:00:59 UTC]

I'm not surprised to see issues with work-in-progress Qt-5.9, but let's see where this goes.

[Comment 3 Davide Pesavento (RETIRED) 2017-05-26 15:10:37 UTC]

From package.mask:

# Michael Palimaka <[e-mail]> (25 Jan 2017)
# Untested work in progress.
# Guaranteed to break your system horribly or your money back.

What part of the above warning you didn't understand? Filing upstream bugs given the current state of gentoo packaging is a waste of time for everyone.

[Comment 4 Matthias Dahl 2017-05-30 07:46:13 UTC]

Since this is indeed a Qt 5.9 last-minute behaviour change that is crashing Plasma (see the associated Qt bug), I have gone ahead and confirmed this bug again, added the upstream bug url and will update the bug again, once a resolution is found -- whatever that may be. Currently it seems like this could get reverted for Qt 5.9 and scheduled for Qt 5.10 ... but let's see.

I think this _is_ important as it will affect all Gentoo users when Qt 5.9 enters the tree -- even though this particular change is currently en route for Qt 5.9.1.

I hope this is okay.

@pesa: I sent you a mail over the weekend explaining things... so I hope everything is fine now.

[Comment 5 Matthias Dahl 2017-06-02 13:53:31 UTC]

Fixed upstream on the 5.9 branch of qtdeclarative:

From ac02a71a9cb8e80014218ba7de46f4f914b6e00c Mon Sep 17 00:00:00 2001
From: Mitch Curtis <[e-mail]>
Date: Tue, 30 May 2017 09:11:28 +0200
Subject: [PATCH] Revert "QQuickWindow::createTextureFromImage(): return
 nullptr for null images"

This reverts commit e6acf80136db9f667d0d4664f6c68065355d6811.

This breaks behavioral compatibility.

Task-number: QTBUG-61083
Change-Id: I0161d536502bab31aaf4ebc38f91e6c8842f72b0
Reviewed-by: Laszlo Agocs <[e-mail]>

[Comment 6 Michael Palimaka (kensington) 2017-06-03 12:12:07 UTC]

Thanks for the investigation and followup, always much appreciated.

[Comment 7 Davide Pesavento (RETIRED) 2017-06-04 20:08:54 UTC]

(In reply to Matthias Dahl from comment #4)
> Since this is indeed a Qt 5.9 last-minute behaviour change that is crashing
> Plasma (see the associated Qt bug), I have gone ahead and confirmed this bug
> again, added the upstream bug url and will update the bug again, once a
> resolution is found -- whatever that may be. Currently it seems like this
> could get reverted for Qt 5.9 and scheduled for Qt 5.10 ... but let's see.

So 5.9.0 final is _not_ affected, correct?

> 
> I think this _is_ important as it will affect all Gentoo users when Qt 5.9
> enters the tree -- even though this particular change is currently en route
> for Qt 5.9.1.
> 
> I hope this is okay.

Absolutely, my apologies. And thanks for investigating the issue and discovering that it was indeed an upstream bug.

[Comment 8 Matthias Dahl 2017-06-06 13:18:29 UTC]

(In reply to Michael Palimaka (kensington) from comment #6)
> Thanks for the investigation and followup, always much appreciated.

You are welcome, always happy to somehow contribute back and help!(In reply to 

Davide Pesavento from comment #7)
> So 5.9.0 final is _not_ affected, correct?

Correct. That particular change was not part of the 5.9.0 final release but scheduled for 5.9.1 (it was on the 5.9 branch).

[Comment 9 Mike Lothian 2017-06-13 11:38:53 UTC]

I seem to be getting crashed in plamsashell with Qt 5.9 & Plamsa 5.10 but only since upgrading to Frameworks 5.35, everything seemed to be fine with 5.34

Is there a way to check if this is the same bug?

[Comment 10 Michael Palimaka (kensington) 2017-06-13 11:40:21 UTC]

(In reply to Mike Lothian from comment #9)
> I seem to be getting crashed in plamsashell with Qt 5.9 & Plamsa 5.10 but
> only since upgrading to Frameworks 5.35, everything seemed to be fine with
> 5.34
> 
> Is there a way to check if this is the same bug?

You could compare your backtrace with the one in comment #0.

[Comment 11 Matthias Dahl 2017-06-13 12:53:58 UTC]

(In reply to Mike Lothian from comment #9)
> I seem to be getting crashed in plamsashell with Qt 5.9 & Plamsa 5.10 but
> only since upgrading to Frameworks 5.35, everything seemed to be fine with
> 5.34
> 
> Is there a way to check if this is the same bug?

If you are using the released Qt 5.9.0, this is most definitely not the same bug. I am running Frameworks 5.35.0 here with Qt 5.9 (latest git) without a hitch.

What you might consider: Try deleting any and all qml caches that are in your home directory. At one point, that caused sddm to crash with the breeze theme. Maybe this is causing a bigger headache in your case.

You can easily spot the caches with: "find ~ -iname "qmlcache" -type d".

If that does not work for you, have you downgraded to 5.34.0 to see if the crashes persist? Maybe you have inadvertently changed/upgraded something else along the way.

Otherwise, a backtrace would be helpful along with more information... but not in this bug report since it is definitely not the same bug if you are on Qt 5.9.0 final. :-)