I have a QML app with linkage (via properties, Q_INVOKABLE, etc) into C++ code. I can launch the QML app without most of the C++ framework using qmlscene, and there are no obvious problems (other than the missing data and functionality that's supposed to be provided from the C++ side).
However, when I build and deploy the code, I get a segfault inside the Qt framework during theQQmlApplicationEngine::load() call.
I've created a simplified "dummy" app that appears to trigger the exact same issue.
C++ App:
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include "SigCatcher.hpp" // Proprietary code
int main(
int argc,
char *argv[])
{
SigCatcher sig_catcher; // Just catches signals & prints stacktrace
QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
engine.load(
QUrl(QStringLiteral("qrc:/main.qml")));
return 0;
}
Note that without the SigCather, I still get a segfault, I just don't get a stack-trace. This example is therefore reproducible if you comment out the SigCatcher import and declaration.
main.qml:
import QtQuick 2.5
import QtQuick.Controls 1.3
import QtCharts 2.0
ApplicationWindow {
id: winRoot
visible: true
width: 1024 - 24
height: 768 - 80
minimumWidth: width
minimumHeight: height
maximumHeight: minimumHeight
maximumWidth: minimumWidth
ChartView {
id: sparkline
anchors.top: parent.top
anchors.right: parent.right
anchors.left: parent.left
}
}
There's almost nothing here, which leads me to believe that the ChartView type itself might have a bug.
What might be going on? I don't even really know how to debug this; as far as I know, there's not even a way to use console.log during engine::load() before calling QGuiApplication::exec().
EDIT: Clarified that the app works correctly with qmlscene (which I didn't know about when I first wrote the question).
EDIT 2: Replaced previous example, which was composed of carefully selected snippets taken from proprietary code, with a complete non-proprietary example that shows the same issue (and has a slightly shorter stacktrace).
Platform info: Qt 5.5.1 running on 64-bit Debian 8; my app is compiled with GCC 5.1, but I see the same error with 4.9.2 and a pre-release version of Clang 3.7.0 that's now about 6 months old. I've also tried using Qt 5.4.0 (which requires importing QtQuick 2.4 instead of 2.5).
Stacktrace:
../obj/X64_ATOM/debug/GUI/AucLocalGui2(_ZN22TracePrinterImpl_Linux16Print_stackTraceEv+0x42)[0x401e54]
../obj/X64_ATOM/debug/GUI/AucLocalGui2(_ZN12TracePrinter16Print_stackTraceEv+0x9)[0x401e7d]
../obj/X64_ATOM/debug/GUI/AucLocalGui2(_ZN20SigCatcherImpl_Linux15OnCatch_signal_Ei+0x68)[0x4022c6]
/lib/x86_64-linux-gnu/libc.so.6(+0x35180)[0x7fe0a2234180]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Widgets.so.5(_ZN18QWidgetTextControl14setCursorWidthEi+0x55)[0x7fe0a527fb15]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Widgets.so.5(_ZN18QWidgetTextControlC1EP7QObject+0x5d)[0x7fe0a527fced]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Widgets.so.5(+0x443047)[0x7fe0a53a6047]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Widgets.so.5(_ZNK17QGraphicsTextItem8documentEv+0xd)[0x7fe0a53a633d]
/opt/Qt/5.5.1/5.5/gcc_64/qml/QtCharts/../../lib/libQt5Charts.so.2(+0x63821)[0x7fe098d74821]
/opt/Qt/5.5.1/5.5/gcc_64/qml/QtCharts/../../lib/libQt5Charts.so.2(+0x56cd3)[0x7fe098d67cd3]
/opt/Qt/5.5.1/5.5/gcc_64/qml/QtCharts/../../lib/libQt5Charts.so.2(+0x5727d)[0x7fe098d6827d]
/opt/Qt/5.5.1/5.5/gcc_64/qml/QtCharts/../../lib/libQt5Charts.so.2(+0x597d6)[0x7fe098d6a7d6]
/opt/Qt/5.5.1/5.5/gcc_64/qml/QtCharts/../../lib/libQt5Charts.so.2(+0x5bb7c)[0x7fe098d6cb7c]
/opt/Qt/5.5.1/5.5/gcc_64/qml/QtCharts/../../lib/libQt5Charts.so.2(+0x5fb8f)[0x7fe098d70b8f]
/opt/Qt/5.5.1/5.5/gcc_64/qml/QtCharts/libqtchartsqml2.so(+0x2f044)[0x7fe099072044]
/opt/Qt/5.5.1/5.5/gcc_64/qml/QtCharts/libqtchartsqml2.so(+0x16680)[0x7fe099059680]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Qml.so.5(_ZNK8QQmlType6createEv+0x3b)[0x7fe0a436e07b]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Qml.so.5(+0x2cf472)[0x7fe0a43cf472]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Qml.so.5(+0x2cc85d)[0x7fe0a43cc85d]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Qml.so.5(+0x2cd45e)[0x7fe0a43cd45e]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Qml.so.5(+0x2cde8e)[0x7fe0a43cde8e]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Qml.so.5(+0x2cea8b)[0x7fe0a43cea8b]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Qml.so.5(+0x2cfcef)[0x7fe0a43cfcef]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Qml.so.5(_ZN20QQmlComponentPrivate11beginCreateEP15QQmlContextData+0x145)[0x7fe0a43592e5]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Qml.so.5(_ZN13QQmlComponent6createEP11QQmlContext+0x68)[0x7fe0a4359728]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Qml.so.5(_ZN28QQmlApplicationEnginePrivate13_q_finishLoadEP7QObject+0x262)[0x7fe0a43c0de2]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Qml.so.5(_ZN28QQmlApplicationEnginePrivate9startLoadERK4QUrlRK10QByteArrayb+0xd2)[0x7fe0a43c1082]
/opt/Qt/5.5.1/5.5/gcc_64/lib/libQt5Qml.so.5(_ZN21QQmlApplicationEngine4loadERK4QUrl+0x1d)[0x7fe0a43c10bd]
../obj/X64_ATOM/debug/GUI/AucLocalGui2(main+0x84)[0x401ae4]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5)[0x7fe0a2220b45]
../obj/X64_ATOM/debug/GUI/AucLocalGui2[0x401959]
setCursorWidth(-1)which then causes a crash inwidth = QApplication::style()->pixelMetric(QStyle::PM_TextCursorWidth);ord->doc->documentLayout()->setProperty("cursorWidth", width);– e.g. when no style or layout is set. Could you add the main function loading all this QML? – Simon Wartaqmlfile directly loaded byQQmlApplicationEngine::load()? I've pared it down to a simpleApplicationWindowcontaining nothing other than a singleSparklineChartelement, but I can post it if you'd like. – Kyle Strand