[Solved] error LNK2001: unresolved external symbol

[silep]

Hello,

I have three errors and I don't know where it comes from and how to solve it. There were not here before. I have shown topics on the internet, but it's very confusing, and the proposals didn't work for me. The errors are

@errorMsg.obj : error LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __thiscall errorMsg::metaObject(void)const " (?metaObject@errorMsg@@UBEPBUQMetaObject@@XZ)

errorMsg.obj : error LNK2001: unresolved external symbol "public: virtual void * __thiscall errorMsg::qt_metacast(char const *)" (?qt_metacast@errorMsg@@UAEPAXPBD@Z)

errorMsg.obj : error LNK2001: unresolved external symbol "public: virtual int __thiscall errorMsg::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@errorMsg@@UAEHW4Call@QMetaObject@@HPAPAX@Z)@

[JohanSolo]

This looks like the moc_errorMsg.cpp is not up to date or not used when linking your application.

[silep]

Yeah that's right at the beginning for the moc generation there is

@errorMsg.h(13): Note: No relevant classes found. No output generated.@

But I really don't know how to fix it.

NB: the file is well included in the .pro file

[JohanSolo]

Did you put the Q_OBJECT macro at the beginning of your class declaration? E.g:

class errorMsg : [...]
{
    Q_OBJECT

[silep]

Yes I did

[JohanSolo]

What does you errorMsg class declaration look like?

[silep]

@#ifndef ERRORMSG_H
#define ERRORMSG_H

class errorMsg : public QObject
{
Q_OBJECT

public:
errorMsg();
~errorMsg();
void writeErrorMsg(QString msg, int value);

};

#endif //ERRORMSG_H@

[JohanSolo]

Apart from the

-errorMsg();

which I assume is a typo, this looks almost OK. You seem to be missing the

#include <QtCore/QObject>

directive.

[silep]

The "~errorMsg();" is the destructor, but it is not so usefull.

I added your include line but it didn't change anything.

My includes are

@#include <QString>
#include <QFile>
#include <QTextStream>
#include <iostream>
#include <QDateTime>
#include <QLabel>
#include <QTextEdit>
#include <QtCore/QObject>
#include "mainform.h"@

[JohanSolo]

[quote author="bern69" date="1396621287"]The "~errorMsg();" is the destructor, but it is not so usefull.
[/quote]
Obviously, but the "-" should read as a "~"...

Indeed the include I told you to add is not needed since many widgets are already included.

I guess you've already tried to rerun qmake and it didn't change a thing.

Could you provide your (complete) .pro file?

Edit: is it only me who sees the tilda as an hyphen?

[bodzio131]

Why would you like to build your errorMsg with Q_OBJECT if you don't declare any signals/slots inside it nor use other Qt's meta-object system services?

[silep]

I removed Q_OBJECT from the class and it works now! Thank you very much! I inserted it because I will program some signals and slots later. If I understand, I have to keep it as commentary until the first slot is inserted?

[bodzio131]

Yes. I don't understand why moc doesn't generate an empty .moc file and some warnings in such case, but it's how it works.