TabWidget segfaults on the Qt backend with the Breeze visual style (Linux)

[griffi-gh]

Bug Description

simply adding this:

TabWidget {
            Tab {
                title: "First";
            }

            Tab {
                title: "Second";
            }
        }

Causes a segfault on linux if the Qt6 backend is used:

Thread 1 "kimchi" received signal SIGSEGV, Segmentation fault.

gdb traceback:

(gdb) where
#0  QTabWidget::documentMode (this=0x0) at /build/qtbase-everywhere-src-6.8.2/src/widgets/widgets/qtabwidget.cpp:1364
#1  0x00007fffe8390237 in Breeze::Style::tabWidgetTabBarRect (this=0x5555576bfaa0, option=0x7ffffffccda0, widget=0x0)
    at /build/breeze-6.3.0/kstyle/breezestyle.cpp:2509
#2  Breeze::Style::tabWidgetTabBarRect (this=0x5555576bfaa0, option=0x7ffffffccda0, widget=0x0)
    at /build/breeze-6.3.0/kstyle/breezestyle.cpp:2500
#3  0x0000555556be3955 in __cpp_closure_5367423239582594642_impl (horizontal=@0x7ffffffcd087: false, size=..., tabbar_size=...)
    at qt_widgets/tabwidget.rs:138
#4  0x0000555556be372d in __cpp_closure_5367423239582594642 (horizontal=@0x7ffffffcd087: false, size=..., tabbar_size=..., 
    __result=0x7ffffffcd088) at qt_widgets/tabwidget.rs:148
#5  0x0000555556bd57ea in i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::{closure#0} (
    orientation=i_slint_core::items::Orientation::Vertical) at qt_widgets/tabwidget.rs:126
#6  0x0000555556bd5931 in i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::{closure#2} () at qt_widgets/tabwidget.rs:153
#7  0x0000555556bd3caa in i_slint_core::properties::{impl#5}::evaluate<i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::TabWidgetMetrics, i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::{closure_env#2}> (self=0x555557710d70, _value=0x555557710ae0)
    at /home/user/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/i-slint-core-1.9.2/properties.rs:745
#8  0x0000555556b8b0a3 in i_slint_core::properties::{impl#8}::set_binding::{closure#0}<i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::TabWidgetMetrics, i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::{closure_env#2}> (val=0x555557710ae0)
    at /home/user/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/i-slint-core-1.9.2/properties.rs:938
#9  0x0000555556b92e8a in i_slint_core::properties::{impl#0}::evaluate<i_slint_core::properties::{impl#8}::set_binding::{closure_env#0}<i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::TabWidgetMetrics, i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::{closure_env#2}>> (self=..., value=0x555557710ae0)
    at /home/user/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/i-slint-core-1.9.2/properties.rs:329
#10 0x0000555556b90f28 in i_slint_core::properties::alloc_binding_holder::evaluate::{closure#0}<i_slint_core::properties::{impl#8}::set_binding::{closure_env#0}<i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::TabWidgetMetrics, i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::{closure_env#2}>> () at /home/user/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/i-slint-core-1.9.2/properties.rs:432
#11 0x0000555556b8dcad in i_slint_core::properties::CURRENT_BINDING::set<i_slint_core::properties::alloc_binding_holder::evaluate::{closure_env#0}<i_slint_core::properties::{impl#8}::set_binding::{closure_env#0}<i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::TabWidgetMetrics, i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::{closure_env#2}>>, i_slint_core::properties::BindingResult> (
    self=0x55555749e738 <i_slint_core::properties::CURRENT_BINDING>, t=..., f=...)
    at /home/user/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/scoped-tls-hkt-0.1.5/src/lib.rs:258
#12 0x0000555556b90a1f in i_slint_core::properties::alloc_binding_holder::evaluate<i_slint_core::properties::{impl#8}::set_binding::{closure_env#0}<i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::TabWidgetMetrics, i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::{closure_env#2}>> (_self=0x555557710d50, value=0x555557710ae0)
    at /home/user/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/i-slint-core-1.9.2/properties.rs:431
#13 0x0000555556b8a809 in i_slint_core::properties::{impl#3}::update::{closure#0}<i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::TabWidgetMetrics> (binding=...) at /home/user/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/i-slint-core-1.9.2/properties.rs:628
#14 0x0000555556b898a2 in i_slint_core::properties::PropertyHandle::access<bool, i_slint_core::properties::{impl#3}::update::{closure_env#0}<i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::TabWidgetMetrics>> (self=0x555557710ad8, f=...)
    at /home/user/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/i-slint-core-1.9.2/properties.rs:533
#15 0x0000555556b8a54e in i_slint_core::properties::PropertyHandle::update<i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::TabWidgetMetrics> (self=0x555557710ad8, value=0x555557710ae0)
    at /home/user/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/i-slint-core-1.9.2/properties.rs:623
#16 0x0000555556b8c093 in i_slint_core::properties::Property<i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::TabWidgetMetrics>::get<i_slint_backend_qt::qt_widgets::tabwidget::{impl#0}::init::TabWidgetMetrics> (self=...)
    at /home/user/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/i-slint-core-1.9.2/properties.rs:829

Reproducible Code (if applicable)

export component AppWindow inherits Window {
    VerticalBox {
        TabWidget {
            Tab {
                title: "First";
            }
            Tab {
                title: "Second";
            }
        }
    }
}

Environment Details

• Slint Version: 1.8
• Platform/OS: Linux (NixOS-unstable) KDE 6.3.0
• Programming Language: Rust
• Backend/Renderer: Qt

Product Impact

No response

[griffi-gh]

RE:
likely an upstream KDE bug

I'll try upgrading Plasma/related packages to 6.3.1 and see if that fixes it
https://invent.kde.org/plasma/breeze/-/commit/f7a14d6d170c17a2c17c386a4c88bfb020e29ff1

[griffi-gh]

Nvm, still happens on KDE 6.3.2, so probably not related to that?

It does only happen with the Breeze visual style though, other styles seem to work fine...
(it crashes as soon i switch back to the Breeze style)

[griffi-gh]

Also tried updating to Slint 1.9 (the default generated by the vscode extension was 1.8)

[ogoffart]

looks like there are more bug in the KDE's breeze style.
We don't have a QWidget to pass to the style function, and the style function should be able to handle that.