Plugin + QObject: undefined symbol

[fem_dev]

I'm writing a set of C-Wrapper functions to my Qt C++ plugins (shared libraries) to enable a pure C call of my library.
It compiles, loads and works good using QLibrary to load this new files at run-time.

My problem is that now I would like to use signals and slots between some internal objects of my myLib.
To enable this, I moved from:

class myLib
{
public:
    myLib();
    ~myLib();
...
}

extern "C" {
    myLib* MYLIB_EXPORT newMyLib(void); // Constructor
}

To a new form:

#include <QObject>

class myLib : public QObject
{
    Q_OBJECT
public:
    explicit myLib(QObject *parent = nullptr);
    ~myLib();
...

Just doing this little movement that I wrote above, when I recompile it and try to load it, I got this run-time load error in my "main application":

undefined symbol: _ZTV6myLib

If I go back to the original version, without QObject, it works good!

Why?
How can I fix it?

My System:

• Ubuntu 20.04 x64
• Qt 5.15.1

[Christian Ehrlicher]

You also have to export your myLib class.

[fem_dev]

@Christian-Ehrlicher said in Plugin + QObject: undefined symbol:

You also have to export your myLib class.

I already tried it, but I got the same run-time error on loading this shared library:

class MYLIB_EXPORT myLib : public QObject
{
    Q_OBJECT
public:
    explicit myLib(QObject *parent = nullptr);
    ~myLib();
...

And again:

undefined symbol: _ZTV6myLib

Any ideas?

[jsulm]

@fem_dev said in Plugin + QObject: undefined symbol:

MYLIB_EXPORT

How is it defined?