Qt.callLater() and invalid context

Kai Nickel

With Qt 6.10 I get an error when using Qt.callLater() in an object that gets destroyed before the delayed call can actually be executed.

Example:

import QtQuick

Window {
    id: root

    Component {
        id: testComp
        QtObject {
            function hello(): void {
                console.log("Hello");
            }
            Component.onCompleted: {
                Qt.callLater(() => hello());
            }
        }
    }

    Loader {
        id: loader
        active: true
        sourceComponent: testComp
    }

    Component.onCompleted: {
        loader.active = false;
    }
}

"Hello" is not printed (which is fine), but then this error comes up:

QQmlVMEMetaObject: Internal error - attempted to evaluate a function in an invalid context
qrc:/IssueTest/Main.qml:13: TypeError: Property 'hello' of object QObject_QML_1(0xe41e9a0) is not a function (exception occurred during delayed function evaluation)

My questions are:

How to use Qt.callLater() safely?
Why did the behavior change? (there was no error in previous Qt versions)
Do you consider this a bug?

SGaist

Hi,

Intuitively, I would say you are using it correctly
Likely an unintended consequence
I would think so
You should check the bug report system to see if this is something known. If not please open a new ticket containing a complete minimal buildable example showing this.