Getting two "LNK2019: unresolved external symbol" using libqrencode

[Emile P]

I made a program on Qt Creator on OSX, but I'm having some issues opening the project on Windows to compile it over there. My program uses the qrencode library (http://fukuchi.org/works/qrencode/), which worked flawlessly on OSX, but I'm having trouble getting it to work here on Windows.
After having a lot of trouble actually installing the library and getting my Qt project to find it, I'm now getting the two LNK2019 errors below:

mainwindow.obj:-1: error: LNK2019: unresolved external symbol _QRcode_free referenced in function "private: void __thiscall MainWindow::updateQRImage(class QString)" (?updateQRImage@MainWindow@@AAEXVQString@@@Z)

mainwindow.obj:-1: error: LNK2019: unresolved external symbol _QRcode_encodeString referenced in function "private: void __thiscall MainWindow::updateQRImage(class QString)" (?updateQRImage@MainWindow@@AAEXVQString@@@Z)

Here is the code that uses the library, as well as the .pro file:

MainWindow::updateQRImage
@
void MainWindow::updateQRImage(QString link)
{
QRcode *qr = QRcode_encodeString(link.toStdString().c_str(), 1, QR_ECLEVEL_L, QR_MODE_8, 1);
QPixmap *QRpixmap = new QPixmap(920, 920);
QPainter painter(QRpixmap);

if(0 != qr) {

    QColor fg("black");
    QColor bg("white");
    painter.setBrush(bg);
    painter.setPen(Qt::NoPen);
    painter.drawRect(0, 0, QRpixmap->width(), QRpixmap->height());
    painter.setBrush(fg);
    const int s = qr->width > 0 ? qr->width : 1;
    const double w = QRpixmap->width();
    const double h = QRpixmap->height();
    const double aspect = w / h;
    const double scale = ((aspect > 1.0) ? h : w) / s;
    for (int y=0; y<s; y++) {
        const int yy = y * s;
        for (int x=0; x<s; x++) {
            const int xx = yy + x;
            const unsigned char b = qr->data[xx];
            if(b &0x01){
                const double rx1=x*scale, ry1=y*scale;
                QRectF r(rx1, ry1, scale, scale);
                painter.drawRects(&r,1);
            }
        }
    }
    QRcode_free(qr);

}
else{
    QColor error("red");
    painter.setBrush(error);
    painter.drawRect(0,0,width(),height());
}
qr = 0;
painter.end();

QPixmap *borderedQR = new QPixmap(1000, 1000);
QPainter borderPainter(borderedQR);

borderPainter.setBrush(QColor("white"));
borderPainter.setPen(Qt::NoPen);
borderPainter.drawRect(0, 0, borderedQR->width(), borderedQR->height());
borderPainter.drawPixmap((borderedQR->width() - QRpixmap->width()) / 2, (borderedQR->height() - QRpixmap->height()) / 2, *QRpixmap);
borderPainter.end();
delete QRpixmap;

this->full_QR_pixmap->swap(*borderedQR);
delete borderedQR;


setImageFromPixmap(*this->full_QR_pixmap, ui->lblQR);

}
@

.pro file
@
#-------------------------------------------------

Project created by QtCreator 2015-06-30T14:13:00

#-------------------------------------------------

QT += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = PlaquesMetalliques
TEMPLATE = app

SOURCES += main.cpp
mainwindow.cpp
croppingwindow.cpp
gui_functions.cpp
aspectratio.cpp
misc_functions.cpp
carddata.cpp
catalogdialog.cpp

HEADERS += mainwindow.h
croppingwindow.h
gui_functions.h
aspectratio.h
misc_functions.h
carddata.h
catalogdialog.h

FORMS += mainwindow.ui
croppingwindow.ui
catalogdialog.ui

RESOURCES +=
defaultressource.qrc

DISTFILES +=
pensees.txt

INCLUDEPATH += $$PWD/include
DEPENDPATH += $$PWD/include

PRE_TARGETDEPS += $$PWD/lib/libqrencode.a

LIBS += $$PWD/lib/libqrencode.a

@CONFIG += debug_and_release@
@

Here is also the include line for the qrencode library, in mainwindow.h
@
#include <qrencode.h>
@

Does anyone know how I could go about fixing this? I've been trying to get the library to work on Windows for over a week now... :|

[SGaist]

Hi and welcome to devnet,

Did you compile libqrencode with the same compiler you are using for your Qt project ? And for the same architecture ?

[Emile P]

@SGaist
I built the libqrencode library using cygwin, with the same commands I had used on OSX (the ones that are recommended on the library's webpage).
I seem to be using different kits than on my Qt Creator on OSX though, which is most likely the source of the issue. I am using Desktop Qt 5.4.2 clang 64bit on OSX, and Desktop 5.5.0 MSVC2010 32bit on Windows. How would I go about fixing this? I don't know anything about adding new kits, and I doubt (after a quick google search) that clang can be used on Windows. :/

[SGaist]

On Windows, you can't mix compilers not even different version of Visual Studio, they are not compatible one with the other. So you have to build libqrencode with Visual Studio 2010

[Emile P]

I will try to build it with Visual Studio 2010 tomorrow, and see if that helps!