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  1. Qt
  2. QTBUG-62007

Crash after instantiating Q_GADGET ctor in QJSEngine

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    • 23cca59848087875ae3486f61d1cd4fe0d90fe7c

    Description

      When instantiating a Q_GADGET using a constructor in some Javascript using QJSEngine, there is a segfault in libQt5Qml.

      Attached sample program causing crash, backtrace and valgrind output.  You can see in the backtrace output that both class constructors are successfully called, but that the program crashes after the call to the Gadget ctor.

      backtrace
      piggz@linux-f1uu ~/projects/build-gadget_crash-Desktop_Qt_5_8_0_GCC_64bit-Debug $ gdb ./gadget_crash 
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Reading symbols from ./gadget_crash...done.
(gdb) r
Starting program: /home/piggz/projects/build-gadget_crash-Desktop_Qt_5_8_0_GCC_64bit-Debug/gadget_crash 
<snip missing symbols>
Created object
Created gadget

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff72518ad in ?? () from /home/piggz/sdks/Qt5.8.0/5.8/gcc_64/lib/libQt5Qml.so.5
(gdb) bt
#0  0x00007ffff72518ad in ?? () from /home/piggz/sdks/Qt5.8.0/5.8/gcc_64/lib/libQt5Qml.so.5
#1  0x00007ffff7252741 in ?? () from /home/piggz/sdks/Qt5.8.0/5.8/gcc_64/lib/libQt5Qml.so.5
#2  0x00007ffff72531ef in ?? () from /home/piggz/sdks/Qt5.8.0/5.8/gcc_64/lib/libQt5Qml.so.5
#3  0x00007ffff72533da in QV4::QMetaObjectWrapper::callConstructor(QQmlPropertyData const&, QV4::ExecutionEngine*, QV4::CallData*) const () from /home/piggz/sdks/Qt5.8.0/5.8/gcc_64/lib/libQt5Qml.so.5
#4  0x00007ffff7253c12 in QV4::QMetaObjectWrapper::constructInternal(QV4::CallData*) const () from /home/piggz/sdks/Qt5.8.0/5.8/gcc_64/lib/libQt5Qml.so.5
#5  0x00007ffff7253c7c in QV4::QMetaObjectWrapper::construct(QV4::Managed const*, QV4::Scope&, QV4::CallData*) () from /home/piggz/sdks/Qt5.8.0/5.8/gcc_64/lib/libQt5Qml.so.5
#6  0x00007ffff726a44c in QV4::Runtime::method_constructActivationProperty(QV4::ExecutionEngine*, int, QV4::CallData*) () from /home/piggz/sdks/Qt5.8.0/5.8/gcc_64/lib/libQt5Qml.so.5
#7  0x00007ffff7e0609c in ?? ()
#8  0x0000000000000000 in ?? ()

      Attachments

        1. backtrace
          2 kB
        2. main.cpp
          1 kB
        3. valgrind
          10 kB
        For Gerrit Dashboard: QTBUG-62007
        # Subject Branch Project Status CR V
        218446,3 Document that Q_GADGET classes cannot be used with newQMetaObject() 5.9 qt/qtdeclarative Status: MERGED +2 0
        218456,1 newQMetaObject(): warn when argument is a Q_GADGET and return null 5.9 qt/qtdeclarative Status: DEFERRED 0 0

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            yulong.bai Bai Yulong
            piggz Adam Pigg
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            Dates

              Created:
              Updated:
              Resolved:

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