C++ Qt: undefined reference to `_imp___ZN12QApplicationC1ERiPPci'

Question

I am trying to remind myself some C++, and also learn about Qt.

I am working on Windows. I have installed Qt (5.1.0), MinGW (g++ 4.6.2), Gnu Make (3.81).

I am trying to compile a simple Qt app. The most basic case is this:

#include <QtWidgets>
#include <QtGui>

int main (int argc, char* argv[]) {               
    QApplication app(argc, argv);                  
    QTextStream cout(stdout);                               
    return EXIT_SUCCESS;
}

The project file is:

TEMPLATE = app
TARGET = example1
INCLUDEPATH += .

# Input
SOURCES += fac1.cpp
QT += gui widgets core

When I run

qmake

it generates the Makefile.

But then with make I get this:

C:\src\early-examples\example1>make
make -f Makefile.Release
make[1]: Entering directory `C:/src/early-examples/example1'
g++ -Wl,-s -Wl,-subsystem,console -mthreads -o release\example1.exe release/fac1.o  -LC:\Qt\Qt5.1.0\\5.1.0\msvc2012_64\lib -lQt5Widgets -lQt5Gui -lQt5Core -llibEGL -llibGLESv2 -lgdi32 -luser32
release/fac1.o:fac1.cpp:(.text.startup+0x2e): undefined reference to `_imp___ZN12QApplicationC1ERiPPci'
release/fac1.o:fac1.cpp:(.text.startup+0x37): undefined reference to `_imp___ZN12QApplicationD1Ev'
collect2: ld returned 1 exit status
make[1]: *** [release\example1.exe] Error 1
make[1]: Leaving directory `C:/src/early-examples/example1'
make: *** [release] Error 2

Can you tell me what is wrong?

Answer 1

The problem here is you appear to be using Visual Studio 2012 libraries for your mingw builds. You need to link to the mingw compiled Qt instead.