Crash due to attempting to restore incompatible window state

[sss123next]

Description

crash on startup

Steps to reproduce

run mumble binary.

Mumble version

0a033af

Mumble component

Client

OS

Linux

Reproducible?

Yes

Additional information

No response

Relevant log output

<W>2024-09-29 23:09:48.940 Theme: "Mumble"
<W>2024-09-29 23:09:48.940 Style: "Dark"
<W>2024-09-29 23:09:48.940 --> qss: ":themes/Default/Dark.qss"
<W>2024-09-29 23:09:48.941 Locale is "ru_RU" (System: "ru_RU")
<W>2024-09-29 23:09:48.978 Database SQLite: "3.46.0"
<W>2024-09-29 23:09:49.901 Updating application palette
[New Thread 0x7fffd3ef66c0 (LWP 246671)]
[New Thread 0x7fffd14f66c0 (LWP 246672)]
[New Thread 0x7fffceaf66c0 (LWP 246673)]
[New Thread 0x7fffc7ef66c0 (LWP 246674)]
[New Thread 0x7fffbbef66c0 (LWP 246675)]
<W>2024-09-29 23:09:49.920 GlobalShortcutX: Using XI2 2.4
<W>2024-09-29 23:09:49.952 QMetaObject::connectSlotsByName: No matching signal for on_qtvUsers_customContextMenuRequested(QPoint,bool)
<W>2024-09-29 23:09:49.952 QMetaObject::connectSlotsByName: No matching signal for on_muteCuePopup_triggered()

Thread 1 ".mumble-wrapped" received signal SIGSEGV, Segmentation fault.
0x00007ffff65c96cc in removeWidgetRecursively(QLayoutItem*, QObject*) () from /nix/store/fa7acm2risfzsqvx90myqavn3bq8fkrw-qtbase-6.7.2/lib/libQt6Widgets.so.6
(gdb) where
#0  0x00007ffff65c96cc in removeWidgetRecursively(QLayoutItem*, QObject*) () from /nix/store/fa7acm2risfzsqvx90myqavn3bq8fkrw-qtbase-6.7.2/lib/libQt6Widgets.so.6
#1  0x00007ffff65c9819 in QLayout::addChildWidget(QWidget*) () from /nix/store/fa7acm2risfzsqvx90myqavn3bq8fkrw-qtbase-6.7.2/lib/libQt6Widgets.so.6
#2  0x00007ffff6742b31 in QMainWindowLayout::splitDockWidget(QDockWidget*, QDockWidget*, Qt::Orientation) ()
   from /nix/store/fa7acm2risfzsqvx90myqavn3bq8fkrw-qtbase-6.7.2/lib/libQt6Widgets.so.6
#3  0x000000000061eaf6 in MainWindow::setupView(bool) ()
#4  0x00000000004a64af in MainWindow::setupGui() ()
#5  0x00000000004de0bd in MainWindow::MainWindow(QWidget*) [clone .constprop.0] ()
#6  0x00000000004e7284 in main ()

### Screenshots

_No response_

[sss123next]

interesting, if i remove ~/.config/Mumble, mumble start successfully (with all settings lost of course)

[Hartmnt]

This reads like the layout of the Mumble client elements might have causing the crash. Have you used a custom layout when it was crashing? If so, do you remember how you had the elements placed?

[Hartmnt]

Do you have - by any chance - kept a copy of the folder when Mumble was crashing?

[sss123next]

it was very old config, maybe i changed something during last 10 years ....

interesting what removing ~/.config/Mumble/Mumble.conf and/or ~/.config/Mumble/Mumble/mumble_settings.json does not resolve problem...

[sss123next]

ok, it seems what problem is in [ui] block, and if configs removed - backups is used.

[sss123next]

ok, found it.

[ui]
░state=@ByteArray(\0\0\0\xff\0\0\0\0\xfd\0\0\0\x1\0\0\0\0\0\0\x2%\0\0\x4R\xfc\x2\0\0\0\x2\xfb\0\0\0\f\0q\0\x64\0w\0L\0o\0g\x1\0\0\0H\0\0\x4)\0\0\0\x82\x1\0\0\a\xfb\0\0\0\xe\0q\0\x64\0w\0\x43\0h\0\x61\0t\x1\0\0\x4u\0\0\0%\0\0\0%\0\0\0%\0\0\x5W\0\0\x4R\0\0\0\x4\0\0\0\x4\0\0\0\b\0\0\0\b\xfc\0\0\0\x1\0\0\0\x2\0\0\0\x1\0\0\0\x1a\0q\0t\0I\0\x63\0o\0n\0T\0o\0o\0l\0\x62\0\x61\0r\x1\0\0\0\0\xff\xff\xff\xff\0\0\0\0\0\0\0\0)⇩  

causing crash

[sss123next]

it's probably wise to implement some validation for whose who update on existing configs

[davidebeatrici]

Thank you for investigating the cause!

The state is loaded and saved in Qt's own format:

mumble/src/mumble/Settings.h

Line 402 in 0a033af

QByteArray qbaMainWindowState = {};

mumble/src/mumble/Settings.cpp

Line 962 in 0a033af

LOAD(qbaMainWindowState, "ui/state");

mumble/src/mumble/MainWindow.cpp

Line 550 in 0a033af

restoreState(Global::get().s.qbaMainWindowState);

mumble/src/mumble/OverlayClient.cpp

Line 223 in 0a033af

Global::get().s.qbaMainWindowState = Global::get().mw->saveState();

This could be considered an upstream bug that we should report...

But yeah, we should probably ignore the window state if Qt's major version doesn't match, in order to prevent potential glitches.

[Krzmbrzl]

@davidebeatrici there exists a version parameter in restoreState for that exact purpose. We probably only have to make use of it:
https://doc.qt.io/qt-6/qmainwindow.html#restoreState