Telegram crash when switching video to Picture-in-Picture on KDE

[mokazemi]

Steps to reproduce

1. Play a video
2. Click on Picture-in-Picture icon
3. It crashes!

Expected behaviour

It should play video without any problem. It used to work before.

Actual behaviour

It just crashes for a few seconds and then telegram closes.

Operating system

Arch Linux

telegram-desktop from Arch linux repos.
Desktop: KDE Plasma 5.26.3, X11

Version of Telegram Desktop

4.3.4

Installation source

Other (unofficial) source

Logs

When running telegram-desktop in terminal:

.
.
.
qt.svg: Error while inflating gzip file: SVG format check failed
qt.svg: Error while inflating gzip file: SVG format check failed
qt.svg: Error while inflating gzip file: SVG format check failed
QTextCursor::setPosition: Position '8388607' out of range
QTextCursor::setPosition: Position '8388607' out of range
Segmentation fault (core dumped)

[ilya-fedin]

There's a regression in Qt 6.4.1, switch to one of the official builds (from https://desktop.telegram.org), they have a fix

[svenstaro]

@ilya-fedin could you post the upstream ticket in Qt for that? We might be able to patch our Qt.

[ilya-fedin]

@svenstaro they have a rule that one has to write a minimal reproducible example when filing a ticket. Sadly, I don't know tdesktop's GL code that good to write one and the person who knows (@john-preston) is unlikely to have spare time to write it and file a ticket.

The affecting commit is qt/qtbase@81252ea (I found it by just diffing src/opengl between v6.4.0 and v6.4.1) and the patch in tdesktop patchset is https://github.com/desktop-app/patches/blob/master/qtbase_6_4_1/0035-Revert-Do-not-use-client-side-data-pointers-in-qopen.patch.

[svenstaro]

Are you generally interested in upstreaming your Qt patches by the way? It would seem to me to be quite the hassle to maintain a patch stack as large as tdesktop's indefinitely.

[ilya-fedin]

I think you need only that patch? No, I don't think I will upstream this patch, last time I tried to fix a crash started happening with v6.4.0 (https://codereview.qt-project.org/c/qt/qtbase/+/434562), they required me to provide a minimum reproducible example and sadly I can't create one, so I abandoned my change, but fortunately by that time @john-preston already made another fix in tdesktop code. If this won't happen that time and no one else would report/fix the bug, the patch is likely to stay indefinitely.

[ilya-fedin]

That may sound ridiculously, but we sadly just don't have enough manpower to conform to Qt's reporting rules. We even have an issue with a list of issues happening due to Qt bugs, so maybe someone from the community would spend time on writing a minimum reproducible example (#25126), but no issue was fixed during this experiment.