connection not found with mingw and cmake

msauer75

Hi,

I converted my Qt project from qmake to cmake with out any problems. With linux (xubuntu) I can sucessful compile my programme and it works fine.
If I switch to windows 10 (Qt 5.15 with mingw 8.1 64bit) I will get a lot of

QObject::connect: signal not found in lib::datad::EnumeratorDecorator
QObject::connect: signal not found in lib::datad::EnumeratorDecorator
QObject::connect: signal not found in lib::datad::EnumeratorDecorator
QObject::connect: signal not found in lib::datad::EnumeratorDecorator
QObject::connect: signal not found in lib::datad::KoordinatenDecorator

and my application doesn't work.

Do you have a solution for this problem?
Thank you for your help.
BR
martin

Christian Ehrlicher

@msauer75 said in connection not found with mingw and cmake:

target_compile_definitions(${LIB} PUBLIC ${LIBDEF})

This is wrong since LIBGC_LIBRARY must only be defined when compiling the library, not when using it. See the cmake documentation --> replace PUBLIC with PRIVATE

Christian Ehrlicher

This has nothing to do with qmake or cmake. You have to export the classes you use from a library on windows: https://doc.qt.io/qt-5/sharedlibrary.html

msauer75

Ok.

My CMakeLists.txt

set(LIBDEF "LIBGC_LIBRARY")
target_compile_definitions(${LIB} PUBLIC ${LIBDEF})

In my libraries I have the following include:

#ifndef LIBGC_GLOBAL_H
#define LIBGC_GLOBAL_H

#include <QtCore/qglobal.h>

#if defined(LIBGC_LIBRARY)
#  define LIBGCSHARED_EXPORT Q_DECL_EXPORT
#else
#  define LIBGCSHARED_EXPORT Q_DECL_IMPORT
#endif

#endif // LIBGC_GLOBAL_H

The class definition:

class LIBGCSHARED_EXPORT Cache : public QObject
{
    Q_OBJECT
    Q_PROPERTY(lib::datad::IntDecorator                             *ui_anzgc           READ GetAnz                 CONSTANT)
    Q_PROPERTY(lib::datad::IntDecorator                             *ui_pos             READ GetPos                 CONSTANT)

 [...]
};

This is the same, which I did in the qmake project.

BR
martin

Christian Ehrlicher

@msauer75 said in connection not found with mingw and cmake:

target_compile_definitions(${LIB} PUBLIC ${LIBDEF})

This is wrong since LIBGC_LIBRARY must only be defined when compiling the library, not when using it. See the cmake documentation --> replace PUBLIC with PRIVATE

msauer75

Ok. That is. Now it works
Thank you

BR
martin