undefined reference errors when using oscpack in QtCreator

Question

I've seen several similar posts but have been unable to fix my specific problem.

I want to use oscpack, described here, http://www.rossbencina.com/code/oscpack

and downloaded here, https://github.com/hecomi/qml-osc and then clicked on the button 'clone or download', then 'Download ZIP' link.

Note: the link I had previously, 'https://storage.googleapis.com/google-code-archive-downloads/v2/code.google.com/oscpack/oscpack_1_1_0.zip' was incorrect.

Note2: I also installed oscpack on my Ubuntu 18.04 system:

$ sudo apt-get -y install liboscpack-dev liboscpack1

After including this library in my project - the moment I add the header files, and - I get multiple undefined reference errors; for example:

undefined reference to `UdpSocket::Connect(IpEndpointName const&)'

I get the errors regardless of whether I use:

LIBS += -L"/developer/3rdPartyLibs/osc/lib" -loscpack # from the downloaded ZIP file

or

LIBS += -L"/usr/lib/x86_64-linux-gnu" -loscpack  # from the linux package

in my SampleProject.pro file.

I saw a very similar post/problem here: Linking a static library to my project on Visual Studio 2010

And I believe I have the same error, and that the solution is similar (it's just that I'm developing on Ubuntu 18.04 instead of Windows). I just haven't figured out how to give the linker what it needs. I expect that the linker can't find the library associated with 'sys/sockets.h', but I don't know where to find it either. I'm using Qt Creator 4.10.2, with Qt_5_13_2_GCC_64bit-Debug.

If you're not familiar with QtCreator but know what command-line arguments need to be passed to ld (and/or g++), that would still be a great help - I can try to figure out where to add that in the IDE.

I suspect no additional information will be required for this problem, but just in case, the code is below.

Thanks!

minimal project (main.qml):

import QtQuick 2.13
import QtQuick.Controls 2.5
import QtQml 2.13
import OSC 1.0

ApplicationWindow {
    visible: true
    width: 640
    height: 480
    title: qsTr("Scroll")


    Rectangle {
        width: 360
        height: 360
        Text {
            id: message
            anchors.centerIn: parent
        }
        OSCReceiver {
            port: 3333
            onMessage: {
                message.text = address + ' : ' + msg;
            }
        }
        OSCSender {
            id: osc
            ip: '127.0.0.1'
            port: 3333
        }
        Timer {
            property int cnt: 0
            interval: 1000/60
            running: true
            repeat: true
            onTriggered: {
                osc.send('/Hoge/cnt', ++cnt);
            }
        }
    }
}

project file (SampleProject.pro):

QT += quick

CONFIG += c++11

# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked deprecated (the exact warnings
# depend on your compiler). Refer to the documentation for the
# deprecated API to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

SOURCES += \
        main.cpp

RESOURCES += qml.qrc

LIBS += -L"/developer/3rdPartyLibs/osc/lib" -loscpack   # add for oscpack

INCLUDEPATH += /developer/3rdPartyLibs/osc              # add for oscpack
include(/developer/3rdPartyLibs/osc/osc.pri)            # add for oscpack

# Additional import path used to resolve QML modules in Qt Creator's code model
QML_IMPORT_PATH =

# Additional import path used to resolve QML modules just for Qt Quick Designer
QML_DESIGNER_IMPORT_PATH =

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

and main.cpp file:

#include <QGuiApplication>
#include <QQmlApplicationEngine>

#include <osc_receiver.h> // add for oscpack
#include <osc_sender.h>   // add for oscpack

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    qmlRegisterType<OSCReceiver>("OSC", 1, 0, "OSCReceiver"); // add for oscpack
    qmlRegisterType<OSCSender>("OSC", 1, 0, "OSCSender");     // add for oscpack

    QQmlApplicationEngine engine;
    const QUrl url(QStringLiteral("qrc:/main.qml"));
    QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                     &app, [url](QObject *obj, const QUrl &objUrl) {
        if (!obj && url == objUrl)
            QCoreApplication::exit(-1);
    }, Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}

This is the output:

14:27:49: Running steps for project SampleProject... 14:27:49: Configuration unchanged, skipping qmake step. 14:27:50: Starting: "/usr/bin/make" -j8 g++ -Wl,-rpath,/opt/Qt/5.13.2/gcc_64/lib -o SampleProject main.o osc_sender.o osc_receiver.o qrc_qml.o moc_osc_sender.o moc_osc_receiver.o -L/developer/3rdPartyLibs/osc/lib -loscpack /opt/Qt/5.13.2/gcc_64/lib/libQt5Quick.so /opt/Qt/5.13.2/gcc_64/lib/libQt5Gui.so /opt/Qt/5.13.2/gcc_64/lib/libQt5Qml.so /opt/Qt/5.13.2/gcc_64/lib/libQt5Network.so /opt/Qt/5.13.2/gcc_64/lib/libQt5Core.so -lGL -lpthread -loscpack osc_sender.o: In function OSCSender::setIp(QString const&)': /developer/builds/qt/build-SampleProject-Desktop_Qt_5_13_2_GCC_64bit-Debug/../../../3rdPartyLibs/osc/osc_sender.cpp:21: undefined reference toUdpSocket::Connect(IpEndpointName const&)' osc_sender.o: In function OSCSender::setPort(int)': /developer/builds/qt/build-SampleProject-Desktop_Qt_5_13_2_GCC_64bit-Debug/Makefile:255: recipe for target 'SampleProject' failed ../../../3rdPartyLibs/osc/osc_sender.cpp:38: undefined reference toUdpSocket::Connect(IpEndpointName const&)' osc_sender.o: In function OSCSender::send(QString const&, QString const&)': /developer/builds/qt/build-SampleProject-Desktop_Qt_5_13_2_GCC_64bit-Debug/../../../3rdPartyLibs/osc/osc_sender.cpp:55 ... ...many similar lines... ... undefined reference toSocketReceiveMultiplexer::~SocketReceiveMultiplexer()' /developer/builds/qt/build-SampleProject-Desktop_Qt_5_13_2_GCC_64bit-Debug/../../../3rdPartyLibs/osc/include/ip/UdpSocket.h:166: undefined reference to UdpSocket::~UdpSocket()' osc_receiver.o: In functionUdpListeningReceiveSocket::Run()': /developer/builds/qt/build-SampleProject-Desktop_Qt_5_13_2_GCC_64bit-Debug/../../../3rdPartyLibs/osc/include/ip/UdpSocket.h:169: undefined reference to SocketReceiveMultiplexer::Run()' osc_receiver.o:(.data.rel.ro._ZTI25UdpListeningReceiveSocket[_ZTI25UdpListeningReceiveSocket]+0x10): undefined reference totypeinfo for UdpSocket' collect2: error: ld returned 1 exit status make: *** [SampleProject] Error 1 14:27:51: The process "/usr/bin/make" exited with code 2.

There is always one and only one reason for undefined reference error - there is a declaration of class/function but the linker can't find an implementation. The zip you've provided doesn't include the lib itself. What is -loscpack? Where did you get the library? Also the package doesn't include osc.pri so where did you get it? The main.qml file you've provided - what that have to show us? It doesn't use some osc items. Please clarify your question. — folibis
@folibis Hello, First of all, I wanted to apologize for the late reply. I did hang around but suspected the 'viewed' counter was updated every time I refreshed, so I started monitoring from my home page in the questions section, and that simply showed a 0 - a newb error. You are correct, that link I put earlier was only a subset of file, as you mentioned; I edited my post and corrected that. No header/library files are now missing. — Marcelo
@folibis Regarding what I'm trying to show, is that I get errors as soon as I add the "include <osc_..." and qmlRegisterType<OSCReceiver>("OSC", ... into the project file. I could include some code trying to actually use oscpack (I removed 99% of my code), but the errors don't seem to change. I got errors as soon as I tried to use their library. I'll gladly add some calls to the library if that will clarify - let me know. — Marcelo
@eyllanesc Hi, I did try to create the minimal reproducible example, as best I could. I did make a mistake with the downloaded file - but that's corrected. This code should generate the errors I listed. Let me know if there is anything specific I should add/changne - thanks! — Marcelo

eyllanesc eyllanesc · Accepted Answer · 2019-12-14T20:59:18

Explanation

The problem is the misunderstanding of how libraries are linked in C++. The qml-osc project to integrate oscpack uses a static link (so it is not necessary to link it dynamically) but unfortunately liboscpack.a is very old generating the problem you observe.

Solution

Considering the above I have made fork of qml-osc eliminating the dependence of the static library so a dynamic link must be used.

Considering the above you must follow the following steps:

install liboscpack-dev

sudo apt-get install liboscpack-dev

Clean your project so that it has the following structure(You can download the files from here):

├── 59331063.pro
├── main.cpp
├── main.qml
└── qml.qrc

Where the .pro is as follows:

QT += quick
CONFIG += c++11
DEFINES += QT_DEPRECATED_WARNINGS
SOURCES += main.cpp
RESOURCES += qml.qrc

INCLUDEPATH += /usr/include/oscpack
LIBS += -loscpack 
include($$PWD/3rdPartyLibs/qml-osc/osc.pri)

Then create a folder called 3rdPartyLibs and clone my repository:

mkdir 3rdPartyLibs && cd 3rdPartyLibs && git clone https://github.com/eyllanesc/qml-osc.git

In the end the project must have the following structure:

├── 3rdPartyLibs
│   └── qml-osc
│       ├── LICENSE
│       ├── osc.pri
│       ├── osc_receiver.cpp
│       ├── osc_receiver.h
│       ├── osc_sender.cpp
│       ├── osc_sender.h
│       └── README.md
├── 59331063.pro
├── main.cpp
├── main.qml
└── qml.qrc

_{At the moment I do not have access to a machine with ubuntu so to test my previous procedure I have used the following Dockerfile}

FROM ubuntu:18.04

MAINTAINER eyllanesc <[email protected]>

RUN apt-get update && \
    apt-get autoclean

RUN apt-get update && apt-get install \
  -y --no-install-recommends \
  git \
  ca-certificates \
  build-essential \ 
  qt5-default \
  qtdeclarative5-dev \
  qml-module-qtquick-controls \
  qml-module-qtquick-controls2 \
  qml-module-qtquick-window2  \
  liboscpack-dev

COPY app app

RUN mkdir app/3rdPartyLibs && \
    cd app/3rdPartyLibs && \
    git clone https://github.com/eyllanesc/qml-osc.git

RUN mkdir app/build && \
    cd app/build && \
    qmake .. && \
    make

CMD app/build/59331063

undefined reference errors when using oscpack in QtCreator

1 Answers

Explanation

Solution