unresolved external symbol "public: static struct QMetaObject const staticMetaObject"

a_coder · 30 Mar 2024, 10:12

i have some error in my code when i build it in visual studio

1>mainw.obj : error LNK2001: unresolved external symbol "public: static struct QMetaObject const Mainw::staticMetaObject" (?staticMetaObject@Mainw@@2UQMetaObject@@B)
1>main.obj : error LNK2001: unresolved external symbol "public: static struct QMetaObject const Workspace::staticMetaObject" (?staticMetaObject@Workspace@@2UQMetaObject@@B)
1>mainw.obj : error LNK2001: unresolved external symbol "public: static struct QMetaObject const Workspace::staticMetaObject" (?staticMetaObject@Workspace@@2UQMetaObject@@B)
1>mainw.obj : error LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __cdecl Mainw::metaObject(void)const " (?metaObject@Mainw@@UEBAPEBUQMetaObject@@XZ)
1>mainw.obj : error LNK2001: unresolved external symbol "public: virtual void * __cdecl Mainw::qt_metacast(char const *)" (?qt_metacast@Mainw@@UEAAPEAXPEBD@Z)
1>mainw.obj : error LNK2001: unresolved external symbol "public: virtual int __cdecl Mainw::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@Mainw@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z)
1>mainw.obj : error LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __cdecl Workspace::metaObject(void)const " (?metaObject@Workspace@@UEBAPEBUQMetaObject@@XZ)
1>mainw.obj : error LNK2001: unresolved external symbol "public: virtual void * __cdecl Workspace::qt_metacast(char const *)" (?qt_metacast@Workspace@@UEAAPEAXPEBD@Z)
1>mainw.obj : error LNK2001: unresolved external symbol "public: virtual int __cdecl Workspace::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@Workspace@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z)

this is my code
mainw.h

#include <ui_mainw.h>
#include <ui_forcus.h>
#include <qmainwindow.h>
#include "control.h"
#include "qprocess.h"

class Timer;
class control;

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

class Mainw : public QMainWindow {
	Q_OBJECT
public:
	void start();
	Mainw(Timer* time, QWidget* parent = nullptr);
	~Mainw();
signals:
	void change_gui() {}
private:
	Ui::Main* ui;
	Timer* timer;
private slots:
	void updatetime(long long time);
	void toworkspace() {
		ui->pushButton->setDisabled(true);
		emit change_gui();
		this->close();
	}
};



class Workspace : public QWidget {
	Q_OBJECT
public:
	Workspace(Timer* time, QWidget* parent = nullptr);
	~Workspace();
	void start();
signals:
	void change_gui() {}
private:
	//store all processes the ui run in a vector
	std::vector<QProcess*> processes;
	Ui::workspace* ui;
	Timer* timer;
private slots:
	void updatetime(long long time);
	void goback();
};
#endif // !MAINWINDOW_H

mainw.cpp

#include <qtimer.h>
#include <qdatetime.h>
#include <qmessagebox.h>
#include "control.h"
#include "mainw.h"
Mainw::Mainw(Timer* time, QWidget* parent)
    :QMainWindow(parent)
    ,timer(time)
    ,ui(new Ui::Main)
{
	ui->setupUi(this);
}

Mainw::~Mainw() {
	delete ui;
}
void Mainw::updatetime(long long time) {
    QLabel* text = ui->label;
    int hour = time / 3600;
    int minutes = time / 60;
    int second = time % 60;
    text->setText(QString("%1:%2:%3")
        .arg(hour, 2, 10, QChar('0'))
        .arg(minutes, 2, 10, QChar('0'))
        .arg(second, 2, 10, QChar('0')));
}
void Mainw::start() {

    QLabel* text = ui->label;
	text->setText("__:__:__");
    text->setAlignment(Qt::AlignCenter);

    connect(timer, &Timer::requestupdated, this, &Mainw::updatetime);

	connect(ui->pushButton, &QPushButton::clicked, this, &Mainw::toworkspace);
	this->raise();
	this->showFullScreen();
    this->show();
}

//setup Workspace
Workspace::Workspace(Timer* time, QWidget* parent)
	:QWidget(parent)
	,ui(new Ui::workspace)
	,timer(time)
{
	ui->setupUi(this);
	connect(timer, &Timer::requestupdated, this, &Workspace::updatetime);
}

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

void Workspace::start() {

	//set text for timer

	QLabel* text = ui->time;
	QLabel* text2 = ui->count;
	text->setText("__:__:__");
	text2->setText("__:__:__");

	//connect button

	connect(timer, &Timer::requestupdated, this, &Workspace::updatetime);
	QPushButton* button = ui->back;
	connect(button, &QPushButton::clicked, this, &Workspace::goback);

	//show workspace

	this->raise();
	this->showFullScreen();
	this->show();
}

void Workspace::updatetime(long long time) {
	//update time remain to label name "timer"
	QLabel* text2 = ui->count;
	int hour2 = time / 3600;
	int minutes2 = time / 60;
	int second2 = time % 60;
	text2->setText(QString("%1:%2:%3")
		.arg(hour2, 2, 10, QChar('0'))
		.arg(minutes2, 2, 10, QChar('0'))
		.arg(second2, 2, 10, QChar('0')));
    //update system time to label name "time"
    QLabel* text = ui->time;
	QDateTime now = QDateTime::currentDateTime();
    text->setText(QString(now.toString("HH:mm:ss")));
}

void Workspace::goback() {
	//show warming message if there is some proess running
	if (processes.size() > 0) {
		QMessageBox msgBox;
		msgBox.setText("There is some proess running,if you exit the process will be close \ndo you want to exit?");
		msgBox.setStandardButtons(QMessageBox::Yes | QMessageBox::No);
		msgBox.setDefaultButton(QMessageBox::No);
		int ret = msgBox.exec();
		if (ret == QMessageBox::Yes) {
			//kill all process in vector
			for (int i = 0; i < processes.size(); i++) {
				processes[i]->kill();
				delete processes[i];
			}
			emit change_gui();
			this->close();
		}
	}
	else {
		emit change_gui();
		this->close();
	}
}

jsulm · 4 May 2024, 05:44

@a_coder said in unresolved external symbol "public: static struct QMetaObject const staticMetaObject":

#include "control.h"

class Timer;
class control;

You have a circular dependency: mainw.h includes control.h and control.h includes mainw.h. This is not going to work. Since you only use Timer* in mainw.h and already have a forward declaration for it, the control.h include is not needed, remove it.

JonB · 30 Mar 2024, 10:20

@a_coder
Did you run a complete rebuild/re-run qmake/cmake/delete build output directory?

a_coder · 30 Mar 2024, 10:31

@JonB sorry, i build it with msvc and i tried to rebuild it but still not work

JonB · 30 Mar 2024, 10:34

@a_coder
It should do. moc needs to be re-run on the file containing the Q_OBJECT macro. I'm pretty sure that is what that linker error stems from. I know nothing about VS. Do you have to install a "plugin" to make it Qt-aware? In the build output filder do you have file names starting with moc_? Can you get VS to show the exact commands it is issuing when rebuilding from scratch?

a_coder · 30 Mar 2024, 11:02

@JonB i use qt extensions to link qt with visual studio and this is my msvc log when i rebuild

Build started at 5:24 CH...
1>------ Build started: Project: project, Configuration: Debug x64 ------
1>Reading Qt configuration (E:/Qt/6.6.2/msvc2019_64/bin/qmake)
1>uic workspace.ui
1>uic mainw.ui
1>moc mainw.h
1>moc control.h
1> G:\project\project\mainw.h(8:1): note: No relevant classes found. No output generated.
1>main.cpp
1>mainw.cpp
1>moc_mainw.cpp
1>moc_control.cpp
1>main.obj : error LNK2001: unresolved external symbol "public: static struct QMetaObject const Mainw::staticMetaObject" (?staticMetaObject@Mainw@@2UQMetaObject@@B)
1>mainw.obj : error LNK2001: unresolved external symbol "public: static struct QMetaObject const Mainw::staticMetaObject" (?staticMetaObject@Mainw@@2UQMetaObject@@B)
1>main.obj : error LNK2001: unresolved external symbol "public: static struct QMetaObject const Workspace::staticMetaObject" (?staticMetaObject@Workspace@@2UQMetaObject@@B)
1>mainw.obj : error LNK2001: unresolved external symbol "public: static struct QMetaObject const Workspace::staticMetaObject" (?staticMetaObject@Workspace@@2UQMetaObject@@B)
1>mainw.obj : error LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __cdecl Mainw::metaObject(void)const " (?metaObject@Mainw@@UEBAPEBUQMetaObject@@XZ)
1>mainw.obj : error LNK2001: unresolved external symbol "public: virtual void * __cdecl Mainw::qt_metacast(char const *)" (?qt_metacast@Mainw@@UEAAPEAXPEBD@Z)
1>mainw.obj : error LNK2001: unresolved external symbol "public: virtual int __cdecl Mainw::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@Mainw@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z)
1>mainw.obj : error LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __cdecl Workspace::metaObject(void)const " (?metaObject@Workspace@@UEBAPEBUQMetaObject@@XZ)
1>mainw.obj : error LNK2001: unresolved external symbol "public: virtual void * __cdecl Workspace::qt_metacast(char const *)" (?qt_metacast@Workspace@@UEAAPEAXPEBD@Z)
1>mainw.obj : error LNK2001: unresolved external symbol "public: virtual int __cdecl Workspace::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@Workspace@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z)
1>G:\project\x64\Debug\project.exe : fatal error LNK1120: 8 unresolved externals
1>Done building project "project.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
========== Build completed at 5:24 CH and took 08,659 seconds ==========

JonB · 30 Mar 2024, 13:03

@a_coder said in unresolved external symbol "public: static struct QMetaObject const staticMetaObject":

G:\project\project\mainw.h(8:1): note: No relevant classes found. No output generated.

I think this looks to be the issue to me. If that indicates that moc did not think your mainw.h did not have recognisable Q_OBJECT macros that would be a problem. I think your mainw.h does have these correctly, so I'm not sure why, but assume the error message is telling us it's a problem.

You have done some hand-coding here, and some if it is not right. For example,:

Any #ifndef MAINWINDOW_H should be right at the start of the header, but you have preceded it by your own '#includes. Though I don't think this would cause your error. But it might do if you have done this in other .h files like control.h.
You use <...> in #include <ui_mainw.h>, but you should not. It is not a "system" include. It should be #include "ui_mainw.h". But again I don't think this would cause your error (though you should change it nonetheless, if there is then a problem something is wrong).
You have #include <ui_forcus.h> in mainw.h. But ui_....h files are only for including into their corresponding .cpp file. This is more worrying, I don't know what effect that might have.

If you cannot get past this, I would suggest you reduce your project to only having the Mainw class. Stop including/compiling/linking anything but the ...mainw... files. And although it should work to have multiple Q_OBJECT classes in your mainw.h file you might get rid of the extra Workspace class while you are having the problem. Get that working. Then add back in the other stuff. You could create a brand new, standalone project with nothing but a MainWindow form and verify that links correctly.

a_coder · 30 Mar 2024, 13:23

@JonB can i put many gui in one .ui file?

Christian Ehrlicher · 30 Mar 2024, 13:43

@a_coder what has this to do with the problem? Make sure you don't have a second header file named the same way somewhere around.

a_coder · 30 Mar 2024, 14:00

@Christian-Ehrlicher of course i don’t have another one named same

Christian Ehrlicher · wrote on 30 Mar 2024, 14:00

@a_coder then cleanup your include and move the ifdef to the top

a_coder · 4 Apr 2024, 10:59

after some edit of my code i think i fixed it but i got some another errors:

1>G:\project\project\control.h(76,7): error C2143: syntax error: missing ';' before '*'
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\control.h(76,7): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\control.h(76,14): error C2238: unexpected token(s) preceding ';'
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\control.h(50,15): error C2061: syntax error: identifier 'Mainw'
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\control.h(50,27): error C2612: trailing ')' illegal in base/member initializer list
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\mainw.h(12,2): warning C4081: expected ')'; found 'string'
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\x64\Debug\moc\moc_mainw.cpp(32,1): warning C4081: expected ')'; found 'string'
1>G:\project\project\x64\Debug\moc\moc_mainw.cpp(160,1): error C1004: unexpected end-of-file found
1>Done building project "project.vcxproj" -- FAILED.
1>Done building project "project.vcxproj" -- FAILED.

i think workspace and mainw class isn't defined in control class although i inclued it
my control.h

#ifndef CONTROLER_H
#define CONTROLER_H

#include <qobject.h>
#include <qtimer.h>
#include <qobject.h>
#include "mainw.h"
#include "workspace.h"


class Timer :public QObject {
	Q_OBJECT
public:
	Timer(long long &timesetup, QObject* parent = nullptr)
		:QObject(parent)
		,counter(new QTimer)
	{
		timereaining = &timesetup;
		connect(counter, &QTimer::timeout, this, &Timer::sendupdate);
	}
	void start() {
		counter->setInterval(1000);
		counter->start();
	}
signals:
	void requestupdated(long long remainsecond);
	void timeout();
private slots:
	void sendupdate() {
		if (*timereaining <= 0) {
			emit timeout();
		}
		else {
			(*timereaining)--;
			emit requestupdated(*timereaining);
		}
	}
private:
	long long* timereaining;
	QTimer* counter;
};

class control :public QObject {
	Q_OBJECT
public:
	control(Timer* time, QObject* parent = nullptr):
		QObject(parent)
		,timer(time)
		, workspace(new Workspace(timer))
		, mainw(new Mainw(timer))
	{
		/*mainw = new Mainw(timer);
		workspace = new Workspace(timer);*/
	}
	~control() {
	}
	void start() {
		connect(mainw, &Mainw::change_gui, this, &control::changeto_workspace_slot);
		connect(workspace, &Workspace::change_gui, this, &control::changeto_mainw_slot);
		mainw->start();
	}
//signals:
	//void changeto_mainw();
	//void changeto_workspace();
private slots:
	void changeto_mainw_slot() {
		mainw->start();
		workspace->close();
	}
	void changeto_workspace_slot() {
		workspace->start();
		mainw->close();
	}
private:
	Timer* timer;
	Mainw* mainw;
	Workspace* workspace;
};
#endif // CONTROLER_H

and i detached mainw and workspace and put it to different header file

jsulm · 4 Apr 2024, 11:03

@a_coder said in unresolved external symbol "public: static struct QMetaObject const staticMetaObject":

1>G:\project\project\control.h(76,7): error C2143: syntax error: missing ';' before '*'
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\control.h(76,7): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')

So, what is in these lines in control.h?
And what is the very first error?

Christian Ehrlicher · 4 Apr 2024, 12:10

apart from the really strange usage of reference and pointers to this reference which will likely not work, don't use 'long long' in signals and slots (or any other 'composed' type as e.g. unsigned int)

a_coder · 4 Apr 2024, 12:12

@Christian-Ehrlicher which vaule i can use in signal and slots?

Christian Ehrlicher · 4 Apr 2024, 13:05

@a_coder said in unresolved external symbol "public: static struct QMetaObject const staticMetaObject":

which vaule i can use in signal and slots?

How should I know which value you send through signals and slot. If you want which datatype then, as I already said, anything which consists of only one word to not confuse the moc compiler.

a_coder · 4 Apr 2024, 13:07

@Christian-Ehrlicher i want to synchronized my countdown from two windows so i send the signal with the time remain in there.however, i don't think that will make the code error

JonB · 4 Apr 2024, 13:34

@a_coder
@Christian-Ehrlicher has suggested you do not use a type written as e.g. long long as a signal parameter, as moc may not like it. I don't know, but I would try obeying his hint and change that to see if it helps.

a_coder · 4 Apr 2024, 13:39

@JonB now i removed long long in signal and it will get that in Timer class but i still got some errors

Build started at 8:33 CH...
1>------ Build started: Project: project, Configuration: Debug x64 ------
1>Reading Qt configuration (E:/Qt/6.7.0/msvc2019_64/bin/qmake)
1>uic mainw.ui
1>uic workspace.ui
1>moc control.h
1>moc mainw.h
1>moc workspace.h
1>main.cpp
1>mainw.cpp
1>workspace.cpp
1>moc_control.cpp
1>moc_mainw.cpp
1>G:\project\project\control.h(77,7): error C2143: syntax error: missing ';' before '*'
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\control.h(77,7): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\control.h(77,14): error C2238: unexpected token(s) preceding ';'
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\control.h(51,15): error C2061: syntax error: identifier 'Mainw'
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\control.h(51,27): error C2612: trailing ')' illegal in base/member initializer list
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\mainw.h(12,2): warning C4081: expected ')'; found 'string'
1>(compiling source file 'x64/Debug/moc/moc_mainw.cpp')
1>G:\project\project\x64\Debug\moc\moc_mainw.cpp(32,1): warning C4081: expected ')'; found 'string'
1>G:\project\project\x64\Debug\moc\moc_mainw.cpp(159,1): error C1004: unexpected end-of-file found
1>Done building project "project.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
========== Build completed at 8:33 CH and took 11,009 seconds ==========

jsulm · wrote on 4 Apr 2024, 13:39

@a_coder Please post current control.h and also mark the line 77 there

a_coder · 4 Apr 2024, 13:52

@jsulm

#ifndef CONTROLER_H
#define CONTROLER_H

#include <qobject.h>
#include <qtimer.h>
#include <qobject.h>
#include "mainw.h"
#include "workspace.h"


class Timer :public QObject {
	Q_OBJECT
public:
	Timer(long long &timesetup, QObject* parent = nullptr)
		:QObject(parent)
		,counter(new QTimer)
	{
		timereaining = &timesetup;
		connect(counter, &QTimer::timeout, this, &Timer::sendupdate);
	}
	long long timeleft() { return *timereaining; }
	void start() {
		counter->setInterval(1000);
		counter->start();
	}
signals:
	void requestupdated();
	void timeout();
private slots:
	void sendupdate() {
		if (*timereaining <= 0) {
			emit timeout();
		}
		else {
			(*timereaining)--;
			emit requestupdated();
		}
	}
private:
	long long* timereaining;
	QTimer* counter;
};

class control :public QObject {
	Q_OBJECT
public:
	control(Timer* time, QObject* parent = nullptr):
		QObject(parent)
		,timer(time)
		, workspace(new Workspace(timer))
		, mainw(new Mainw(timer))
	{
		/*mainw = new Mainw(timer);
		workspace = new Workspace(timer);*/
	}
	~control() {
	}
	void start() {
		connect(mainw, &Mainw::change_gui, this, &control::changeto_workspace_slot);
		connect(workspace, &Workspace::change_gui, this, &control::changeto_mainw_slot);
		mainw->start();
	}
//signals:
	//void changeto_mainw();
	//void changeto_workspace();
private slots:
	void changeto_mainw_slot() {
		mainw->start();
		workspace->close();
	}
	void changeto_workspace_slot() {
		workspace->start();
		mainw->close();
	}
private:
	Timer* timer;
	Mainw* mainw; //line 77
	Workspace* workspace;
};
#endif // CONTROLER_H

sorry idk how to mark that