Live preview crashes with PopupWindow

[petiaccja]

Bug Description

Live preview crashes with PopupWindow:

thread 'main' panicked at internal\interpreter\eval.rs:1842:71:
called `Option::unwrap()` on a `None` value
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
[Info  - 9:00:33 PM] Connection to server got closed. Server will restart.
true
The Slint Language Server crashed. This is a bug. Please open an issue on https://github.com/slint-ui/slint/issues
[Error - 9:00:33 PM] Server process exited with code 3221226505.

Steps to reproduce (see code below):

1. Launch LivePreviewTest in live preview using VSCode's inline actions
2. Click "Show warning" on the live preview window
3. Click either "Continue" or "Cancel"
4. Panic

Unfortunately I don't have the stacktrace as I'm not sure how to get it with the live preview. I haven't had the chance yet to test the Slint code by running the Rust application itself. I'm also unsure if the rest of the Slint code affects the live preview for these two files, but I would guess not.

Reproducible Code (if applicable)

// File "prototype_popup.slint"
import { Palette } from "std-widgets.slint";

export component PrototypePopup inherits PopupWindow {
    Rectangle {
        background: Palette.background;
        border-radius: 16px;
        drop-shadow-color: #00000080;
        drop-shadow-blur: 12px;
        drop-shadow-offset-x: 2px;
        drop-shadow-offset-y: 2px;
        opacity: 95%;
    }

    Rectangle {
        background: Palette.control-background;
        border-radius: 16px;
        opacity: 95%;
    }
}

// File "warning_popup.slint"
import { PrototypePopup } from "prototype_popup.slint";
import { Button } from "std-widgets.slint";

export component WarningPopup inherits PrototypePopup {
    width: 400px;
    height: self.min-height;
    in property <bool> continue-enabled: true;
    in property <bool> cancel-enabled: true;
    in property <string> continue-text: "Continue";
    in property <string> cancel-text: "Cancel";
    callback continued();
    callback cancelled();
    content := VerticalLayout {
        spacing: 12px;
        padding: 12px;
        HorizontalLayout {
            alignment: center;
            spacing: 6px;
            VerticalLayout {
                alignment: center;
                // Redacted (does not change behavior)
            }

            @children
        }

        HorizontalLayout {
            alignment: end;
            spacing: 6px;
            if root.continue-enabled: Button {
                text: root.continue-text;
                width: 96px;
                clicked => {
                    root.close();
                    root.continued();
                }
            }
            if root.cancel-enabled: Button {
                text: root.cancel-text;
                width: 96px;
                clicked => {
                    root.close();
                    root.cancelled();
                }
            }
        }
    }
}

export component LivePreviewTest {
    warning := WarningPopup {
        x: (root.width - self.width) / 2;
        y: (root.height - self.height) / 2;
        Text {
            text: "Bad things might happen!";
        }
    }

    Button {
        text: "Show warning";
        clicked => {
            warning.show();
        }
    }
}

Environment Details

• Slint Version: 1.9.2
• Platform/OS: Windows 11
• Programming Language: Slint (live preview)
• Backend/Renderer: live preview default
• VSCode Extension Version: 1.10.0

Product Impact

No response

[petiaccja]

It may be useful info:

• removing the callbacks from the clicked handlers does not panic
• factoring out the clicked handler into a separate self-level function that calls both continued and close fixes the issue

[petiaccja]

There is another related issue:

export component WarningPopup [...] {
    function continue() {
        root.close(); // << Problem here
        self.continued();
    }
}

export component LivePreviewTest {
    warning := WarningPopup {
        // ...
        continued => {} // << Problem here
    }

    // ...
}

If root.close() is present in WarningPopup's factored out click handler, then adding any callback handler for continue in a parent component will panic:

thread 'main' panicked at internal\interpreter\dynamic_item_tree.rs:1449:43:
called `Option::unwrap()` on a `None` value
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
[Info  - 11:04:17 AM] Connection to server got closed. Server will restart.
true
The Slint Language Server crashed. This is a bug. Please open an issue on https://github.com/slint-ui/slint/issues
[Error - 11:04:17 AM] Server process exited with code 3221226505.

[ogoffart]

Thanks for the Bug report.

Here is a shorter testcase:

import {  Button } from "std-widgets.slint";
export component LivePreviewTest {
    in property <bool> cancel-enabled: true;
    callback cancelled();
    warning := PopupWindow {
        Rectangle {
            background: gray;
        }
        content := VerticalLayout {
            alignment: end;
            spacing: 6px;
            if root.cancel-enabled: Button {
                text: "Close Popup";
                width: 96px;
                clicked => {
                    warning.close();
                    root.cancelled();
                }
            }
        }
    }

    Button {
        text: "Show warning";
        clicked => {
            warning.show();
        }
    }
}

The problem is again that we access property of parent item. So this is a duplicate of #6426

I'm going to close it as duplicate, but thanks for reporting the bug anyway.