Vcpkg: Building simple Qt application after installation failed

[usernameiwantedwasalreadytaken]

I've installed the qt5 module and I'm trying to build a simple project with just one file:

#include <QtWidgets/QApplication.h>
#include <QtWidgets/QMainWindow.h>

int main(int argc, char** argv) {
    QApplication app { argc, argv };
    QMainWindow mainWindow;

    mainWindow.show();
    return app.exec();
}

Visual Studio can compile fine, but gives me the following error when linking:

1>------ Build started: Project: Basic, Configuration: Release Win32 ------
1>main.cpp
1>Qt5AxServer.lib(qaxserver.obj) : error LNK2001: unresolved external symbol "class QAxFactory * __cdecl qax_instantiate(void)" (?qax_instantiate@@YAPAVQAxFactory@@XZ)
1>C:\Tests\Qt\QtSamples\Release\Basic.exe : fatal error LNK1120: 1 unresolved externals
1>Done building project "Basic.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Any ideas how I might solve this?

P.S.: With a Debug build I've got many more linking errors...

I'm using Visual Studio 2017 Community.

Thanks in advance.

[usernameiwantedwasalreadytaken]

So, if I manually delete Qt5AxServer.lib and Qt5AxServerd.lib from <vcpkg>\installed\*\lib and <vcpkg>\installed\*\debug\lib everything works.

[ShinNoNoir]

I'd like to add that for the Debug configuration, <vcpkg>\installed\*\debug\lib\Qt5Bootstrap.lib should also be deleted. Qt5Bootstrap.lib is linked with MD_DynamicRelease and is only meant for Release builds.

[ShinNoNoir]

Reading a bit more about Qt, it seems that depending on your use case, you either:

• Link qtmain.lib (rel) or qtmaind.lib (dbg);
• Or link Qt5AxServer.lib (rel) or Qt5AxServerd.lib (dbg).

Source: http://doc.qt.io/qt-5/activeqt-server.html

Does vcpkg offer any way of selecting which libs will be included in the linking process?

[ShinNoNoir]

Does vcpkg offer any way of selecting which libs will be included in the linking process?

Okay, after browsing through some source files and other portfile.cmakes, I think the following probably should happen:

• debug\lib\Qt5Bootstrap.lib must be deleted;
• Qt5AxServer.lib should be moved from lib to lib\manual-link;
• Qt5AxServerd.lib should be moved from debug\lib to debug\lib\manual-link;
• qtmain.lib should be moved from lib to lib\manual-link;
• qtmaind.lib should be moved from debug\lib to debug\lib\manual-link;

Users need to:

• Explicitly add qtmain.lib/qtmaind.lib as a dependency for Qt desktop applications for release/debug configurations.
• Explicitly add Qt5AxServer.lib/Qt5AxServerd.lib as a dependency for Qt ActiveX server applications for release/debug configurations.

[JackBoosY]

Hi @usernameiwantedwasalreadytaken, thanks for reporting this issue.
Since qt5 has been upgraded to 5.12.5, this issue may be fixed.
So please update vcpkg and rebuild qt5.

Thanks.

[JackBoosY]

@Neumann-A I think this issue is resolved in some PRs, is it correct?

[Neumann-A]

@JackBoosY: I think this:

Qt5AxServer.lib should be moved from lib to lib\manual-link;
Qt5AxServerd.lib should be moved from debug\lib to debug\lib\manual-link;

still needs to be resolved