If class with Q_OBJECT is in header file than Generated File is named moc_xxx.cpp and there are no issues.

If class with Q_OBJECT is in cpp file than Generated File is xxx.moc and warning MSB8017 is output:

A circular dependency has been detected while executing custom build commands for item "GeneratedFiles\Debug\main.moc". This may cause incremental build to work incorrectly.

Code example – just put this into main.cpp, save and build with Visual Studio:

#include <QtCore/QCoreApplication>

class AddInHatesThis : public QObject
{
	Q_OBJECT

public:
	AddInHatesThis() {}
	virtual ~AddInHatesThis() {}
};

int main(int argc, char *argv[])
{
	QCoreApplication a(argc, argv);

	return a.exec();
}