Crash in custom widget example

[zing0000]

I built customwidgetplugin using Qt Creator.

I created a minimum Qt Application (testwidget.vcproj) in VS2008 using the VS2008 add-in.

I opened testwidget.ui in Qt Designer and added the Widget, - object name is analogClock.

Back to VS2008.

• I copy analogclock.h into the project directory.
• I copy customwidgetplugin dll, lib and pdb into .\Debug directory.

The project builds with no errors or warnings.

I launch testwidget.exe and it finds and loads the plug-in.
But then it crashes at the constructor.

void setupUi(QMainWindow *testwidgetClass)
{
    if (testwidgetClass->objectName().isEmpty())
        testwidgetClass->setObjectName(QString::fromUtf8("testwidgetClass"));
    testwidgetClass->resize(450, 316);
    centralWidget = new QWidget(testwidgetClass);
    centralWidget->setObjectName(QString::fromUtf8("centralWidget"));
    analogClock = new AnalogClock(centralWidget);

I have not modified or added a single line of code, but clearly I am misusing the tools in some way.

Here is the VS2008 output
'testwidget.exe': Loaded 'D:\Smartience2AV\MeeGo\testwidget\Debug\testwidget.exe', Symbols loaded.
'testwidget.exe': Loaded 'C:\Windows\System32\ntdll.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\kernel32.dll'
'testwidget.exe': Loaded 'D:\NokiaQt\Qt4.7.1\bin\QtCored4.dll', Symbols loaded.
'testwidget.exe': Loaded 'C:\Windows\System32\user32.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\gdi32.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\advapi32.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\rpcrt4.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\ole32.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\msvcrt.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\ws2_32.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\nsi.dll'
'testwidget.exe': Loaded 'C:\Windows\winsxs\x86_microsoft.vc90.debugcrt_1fc8b3b9a1e18e3b_9.0.30729.4148_none_2a4cbfc25558bcd3\msvcp90d.dll', Symbols loaded.
'testwidget.exe': Loaded 'C:\Windows\winsxs\x86_microsoft.vc90.debugcrt_1fc8b3b9a1e18e3b_9.0.30729.4148_none_2a4cbfc25558bcd3\msvcr90d.dll', Symbols loaded.
'testwidget.exe': Loaded 'D:\NokiaQt\Qt4.7.1\bin\QtGuid4.dll', Symbols loaded.
'testwidget.exe': Loaded 'C:\Windows\System32\comdlg32.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\shlwapi.dll'
'testwidget.exe': Loaded 'C:\Windows\winsxs\x86_microsoft.windows.common-controls_6595b64144ccf1df_5.82.6001.18523_none_886c608850a2f36f\comctl32.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\shell32.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\oleaut32.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\imm32.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\msctf.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\winmm.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\oleacc.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\winspool.drv'
'testwidget.exe': Loaded 'D:\Smartience2AV\MeeGo\testwidget\Debug\customwidgetplugin.dll', Binary was not built with debug information.
'testwidget.exe': Loaded 'D:\NokiaQt\Qt4.7.1\bin\QtGui4.dll', Binary was not built with debug information.
'testwidget.exe': Loaded 'D:\NokiaQt\Qt4.7.1\bin\QtCore4.dll', Binary was not built with debug information.
'testwidget.exe': Loaded 'C:\Windows\winsxs\x86_microsoft.vc90.crt_1fc8b3b9a1e18e3b_9.0.30729.4148_none_5090ab56bcba71c2\msvcp90.dll', Symbols loaded.
'testwidget.exe': Loaded 'C:\Windows\winsxs\x86_microsoft.vc90.crt_1fc8b3b9a1e18e3b_9.0.30729.4148_none_5090ab56bcba71c2\msvcr90.dll', Symbols loaded.
'testwidget.exe': Loaded 'C:\Windows\System32\lpk.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\usp10.dll'
'testwidget.exe': Loaded 'C:\Windows\winsxs\x86_microsoft.windows.common-controls_6595b64144ccf1df_6.0.6001.18523_none_5cdd65e20837faf2\comctl32.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\uxtheme.dll'
'testwidget.exe': Loaded 'C:\Program Files\SetPoint\lgscroll.dll', Binary was not built with debug information.
'testwidget.exe': Loaded 'C:\Windows\winsxs\x86_microsoft.vc80.crt_1fc8b3b9a1e18e3b_8.0.50727.4053_none_d08d7da0442a985d\msvcr80.dll'
'testwidget.exe': Loaded 'C:\Windows\winsxs\x86_microsoft.vc80.crt_1fc8b3b9a1e18e3b_8.0.50727.4053_none_d08d7da0442a985d\msvcp80.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\ntmarta.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\Wldap32.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\psapi.dll'
'testwidget.exe': Loaded 'C:\Windows\System32\samlib.dll'
The program '[7424] testwidget.exe: Native' has exited with code 1 (0x1).

Everything looks good until it dies in the constructor. Dependency Walker shows the entry point is there...

[IrQX]

Have you included "widget.h, widget.cpp and widget.ui" files to your project?

[zing0000]

Yes, they are. And as the entry point is visible with Dependency Walker, it would appear that everything built correctly.

The problem is that I cannot debug into the DLL because it was not built in VS2008. Can anyone recommend a way forward (or make a divine guess as to the cause of the problem in the first place!)

[giesbert]

Did you change QtCreator to use the MSVC compiler? Or do you use creator with gcc? If you use it with gcc, it will not work together with a MSVC project.
And as far as I know, plug-ins must be located inside a subdirectory plugins, don't they?

[goetz]

[quote author="zing0000" date="1290662221"]The problem is that I cannot debug into the DLL because it was not built in VS2008. Can anyone recommend a way forward (or make a divine guess as to the cause of the problem in the first place!)
[/quote]

You cannot mix C++ libs compiled with different versions of Visual Studio. All C++ code must be compiled with VS2008, including the Qt libs (there are prebuild binaries on the "downloads page":http://qt.nokia.com/downloads).

[giesbert]

You can't mix if the libs are not memory clean (which means the memory that is allocated inside the lib is also freed in the lib). If it's memory clean, it is possible. But with using Qt classes, it's not....

[goetz]

Even if they are memory clean, it's not advisable, because they depend on different major versions of the C++ standard libs (MSVCPxx.DLL). This may cause different behaviour on method/function calls due to different implementations or default values.

[giesbert]

That is true, but in general it works (we have such stuff here, even I don't like that). But it only works, if the libs are memory clean. By the way, I didn't say that I like that :-)

[goetz]

We all do like the DLL hell together with the new manifest fiasco, don't we? :-)

[zing0000]

Success!

In Qt Creator, Projects tab, Build settings - I was correctly using the Microsoft Visual C++ tool chain BUT I had not selected the Release build.

The docs clearly state you must use a release build in VS2008.

Now it works, and I can debug into the DLL from VS2008.