Qt5 and MacOS X - qt

Question

I've installed Qt5 on my Mac OS X Yosemite from MacPorts.
If I compile this simple file
#include <QtGui>
#include <QtWidgets/QApplication>
#include <QtWidgets/QLabel>
int main(int argc, char **argv)
{
QApplication app(argc, argv);
QLabel lbl("Hello World!");
lbl.show();
return app.exec();
}
I'll get error
Undefined symbols for architecture x86_64:
"QApplication::exec()", referenced from:
_main in main.o
"QApplication::QApplication(int&, char**, int)", referenced from:
_main in main.o
"QApplication::~QApplication()", referenced from:
_main in main.o
"QLabel::QLabel(QString const&, QWidget*, QFlags<Qt::WindowType>)", referenced from:
_main in main.o
"QLabel::~QLabel()", referenced from:
_main in main.o
"QWidget::show()", referenced from:
_main in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [123.app/Contents/MacOS/123] Error 1
I've change QMAKE_MACOSX_DEPLOYMENT_TARGET = 10.6
to QMAKE_MACOSX_DEPLOYMENT_TARGET = 10.9
or QMAKE_MACOSX_DEPLOYMENT_TARGET = 10.10
in file /opt/local/share/qt5/mkspecs/macx-clang/qmake.conf
but it has no result.

Answer 1

Hard to know exactly without more information, but check that you are adding in widgets in your .pro file:
QT += gui core
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
You may have to run qmake explicitly if you aren't using qtcreator. Also, wouldn't you be showing a main window instead of a QLabel? I haven't checked if that's legit doable code, but maybe you should start showing a main window and verify that works first. QTCreator has a project template for a new Qt Widgets Application. Also check to see that macports is installing the latest qt5 version in the event it's a bad path or config on their part.