Library linking error: undefined reference to _imp__

Question

I can't figure out how to link FTDI library in my Qt project. I copied ftd2xx.h file to my project directory. The file I want to link is dll: ftd2xx.lib which is stored in F:\\Workspace\\qt\\libs\\ftdi\\amd64

I get error:

release/testftdi.o:testftdi.cpp:(.text+0x6f8): undefined reference to `_imp__FT_Open@8'
collect2.exe: error: ld returned 1 exit status

I have QtWidget application with one PushButton:

TestFtdi.pro file:

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = TestFtdi
TEMPLATE = app

LIBS += -L"F:\Workspace\qt\libs\ftdi\amd64" -lftd2xx
INCLUDEPATH += f:/Workspace/qt/libs/ftdi/amd64

SOURCES += main.cpp\
        testftdi.cpp

HEADERS  += testftdi.h

FORMS    += testftdi.ui

main.cpp file:

#include "testftdi.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    TestFtdi w;
    w.show();

    return a.exec();
}

testftdi.h file:

#ifndef TESTFTDI_H
#define TESTFTDI_H

#include <QMainWindow>

namespace Ui {
class TestFtdi;
}

class TestFtdi : public QMainWindow
{
    Q_OBJECT

public:
    explicit TestFtdi(QWidget *parent = 0);
    ~TestFtdi();

private slots:
    void on_pushButton_clicked();

private:
    Ui::TestFtdi *ui;
};

#endif // TESTFTDI_H

testftdi.cpp file:

#include "testftdi.h"
#include "ui_testftdi.h"
#include <QDebug>

#include "windows.h"
#include "ftd2xx.h"

TestFtdi::TestFtdi(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::TestFtdi)
{
    ui->setupUi(this);
}

TestFtdi::~TestFtdi()
{
    delete ui;
}

void TestFtdi::on_pushButton_clicked()
{

    FT_HANDLE ftHandle;
    FT_STATUS ftStatus;


    ftStatus = FT_Open(0, &ftHandle);
    if(ftStatus != FT_OK) { // FT_Open failed
        qDebug() << "FT_Open failed";
    }
}

The compiler command looks in this situation like this:

g++ -Wl,-s -Wl,-subsystem,windows -mthreads -o release\TestFtdi.exe release/main.o release/testftdi.o release/moc_testftdi.o  -lmingw32 -LC:/Qt/5.5/mingw492_32/lib -lqtmain -lshell32 -LF:\Workspace\qt\libs\ftdi\Static\amd64 -lftd2xx -lQt5Widgets -lQt5Gui -lQt5Core 

Could you help me with this?

Answer 1

My guess is, compiler might be looking for ftd2xx rather than ftd2xx.lib (file name is ftd2xx.lib.dll, right?). Have you tried changing the LIBS line to

LIBS += -L"F:\Workspace\qt\libs\ftdi\amd64" -lftd2xx.lib