Loading...

XML

Word

Printable

Details

Type: Bug
Resolution: Done
Priority: P1: Critical
Fix Version/s: 5.9.2
Affects Version/s: 5.6.2, 5.7.1
Component/s: QML: Declarative and Javascript Engine
Labels:
- Reported_by_support_premium

Description

Consider the following QML singleton declared in module "constants":

Sing.qml

pragma Singleton

import QtQuick 2.4

QtObject {
    readonly property string song: "Highway to Hell"
}

We have a QML component that returns 2 callbacks:

Page.qml

import QtQuick 2.5

import constants 1.0

Item {
    id: root

    function crash() {
        return function() {
            return Sing.song;
        }
    }

    function work() {
        var s = Sing;
        return function() {
            return s.song;
        }
    }
}

These callbacks can also be properties, with the same result.

Page.qml is loaded from Test.qml as follows:

Test.qml

import QtQuick 2.5

import constants 1.0

Rectangle {
    color: "white"
    width: 400
    height: 400

    Timer {
        id: _timer
        interval: 1000
        repeat: true
        triggeredOnStart: true
    }

    Loader {
        id: ldr
        source: "Page.qml"
        active: false
        onLoaded: {
            var item = ldr.item;
//            var work = item.work();
            var crash = item.crash();
            _timer.triggered.connect(function() {
//                console.warn("work:  ", item, work());
                console.warn("crash: ", item, crash());
                ldr.active = false;
            });
            _timer.start();
        }
    }

    Component.onCompleted: {
        console.warn(Sing.song);
        ldr.active = true;
    }
}

This code causes the application to crash with segmentation fault on the second invocation of the callback, when the Page is destroyed:

% qmlscene -I . Test.qml

qml: Highway to Hell
qml: crash:  Page_QMLTYPE_1(0x1795750) Highway to Hell
zsh: segmentation fault qmlscene -I . Test.qml

If I uncomment "work" callback and comment "crash", the application works and the output is this:

% qmlscene -I . Test.qml

qml: Highway to Hell
qml: work:    Page_QMLTYPE_1(0x2e99bb0) Highway to Hell
qml: work:    TypeError: Type error Highway to Hell
qml: work:    TypeError: Type error Highway to Hell
qml: work:    TypeError: Type error Highway to Hell
...

I have 5.6.2 compiled from sources, this is the backtrace:

#0  0x00007ffff701e700 in QV4::ExecutionEngine::qmlSingletonWrapper (this=0x7e4430, name=0x7fffe2d38450) at /home/ABusenius/qtdeclarative/src/qml/jsruntime/qv4engine.cpp:721
#1  0x00007ffff70fc4e6 in QV4::Runtime::getQmlSingleton (engine=0x7e4430, nameIndex=6) at /home/ABusenius/qtdeclarative/src/qml/jsruntime/qv4runtime.cpp:1471
#2  0x00007ffff7fc9992 in ?? ()
#3  0x00007ffff7ecfe70 in ?? ()
#4  0x00007ffff7ecfe70 in ?? ()
#5  0x00007fffe2d383e8 in ?? ()
#6  0xd1e1af7c21137e00 in ?? ()
#7  0x00007fffffffcb50 in ?? ()
#8  0x00007ffff7025526 in QV4::FunctionObject::function (this=0x7fffe2d383e8) at /home/ABusenius/qtdeclarative/src/qml/jsruntime/qv4functionobject_p.h:134
#9  0x00007ffff70671fc in QV4::SimpleScriptFunction::call (that=0x7ffff7e2e080, callData=0x7fffe2d383a8) at /home/ABusenius/qtdeclarative/src/qml/jsruntime/qv4functionobject.cpp:576
#10 0x00007ffff6f99b34 in QV4::Object::call (this=0x7ffff7e2e080, d=0x7fffe2d383a8) at ../../include/QtQml/5.6.2/QtQml/private/../../../../../../qtdeclarative/src/qml/jsruntime/qv4object_p.h:326
#11 0x00007ffff70fa697 in QV4::Runtime::callValue (engine=0x7e4430, func=..., callData=0x7fffe2d383a8) at /home/ABusenius/qtdeclarative/src/qml/jsruntime/qv4runtime.cpp:1034
#12 0x00007ffff7fc96d7 in ?? ()
#13 0x00007ffff7ecfed0 in ?? ()
#14 0x00007ffff7ecfed0 in ?? ()
#15 0x00007fffe2d38360 in ?? ()
#16 0xd1e1af7c21137e00 in ?? ()
#17 0x00007fffffffcd60 in ?? ()
#18 0x00007ffff7025526 in QV4::FunctionObject::function (this=0xa348f0) at /home/ABusenius/qtdeclarative/src/qml/jsruntime/qv4functionobject_p.h:134
#19 0x00007ffff70671fc in QV4::SimpleScriptFunction::call (that=0x7fffe2d38318, callData=0x7fffe2d38320) at /home/ABusenius/qtdeclarative/src/qml/jsruntime/qv4functionobject.cpp:576
#20 0x00007ffff6f99b34 in QV4::Object::call (this=0x7fffe2d38318, d=0x7fffe2d38320) at ../../include/QtQml/5.6.2/QtQml/private/../../../../../../qtdeclarative/src/qml/jsruntime/qv4object_p.h:326
#21 0x00007ffff70dbbd9 in QV4::QObjectSlotDispatcher::impl (which=1, this_=0xa348f0, r=0x966b60, metaArgs=0x7fffffffd080, ret=0x0) at /home/ABusenius/qtdeclarative/src/qml/jsruntime/qv4qobjectwrapper.cpp:813
#22 0x00007ffff559cbfe in QMetaObject::activate(QObject*, int, int, void**) () from /home/abusenius/qt/5.6/gcc_64/bin/../lib/libQt5Core.so.5
#23 0x00007ffff724876d in QQmlTimer::triggered (this=0x966b60) at .moc/moc_qqmltimer_p.cpp:260