how to create plugins (Qt 5.2.0) - c++

Question

i ‘m trying to create a plugin(not for Qt creator),
i created an empty project and added the following files :
but i’m getting the following errors:
1.
C:\Qt\Qt5.2.0\5.2.0\mingw48_32\include\QtCore\qglobal.h:666: erreur : invalid application of ‘sizeof’ to incomplete type ‘QStaticAssertFailure’ enum {Q_STATIC_ASSERT_PRIVATE_JOIN(q_static_assert_result, COUNTER) = sizeof(QStaticAssertFailure)} ^
2.
D:\MyFiles\Projects\QtProjects\pluginTest2\plugintest.cpp:9: erreur : expected initializer before ‘PluginTest’ QString PluginTest::name() const ^
PluginTest2.pro (project name)
CONFIG += plugin
TARGET = PluginTest
CONFIG += plugin release
VERSION =1.0.0
TEMPLATE = lib
SOURCES += \
plugintest.cpp
HEADERS += \
Interface.h \
plugintest.h
interface.h
#ifndef INTERFACE_H
#define INTERFACE_H
#include <QString>
class Interface
{
public:
virtual QString name() const =0;
};
Q_DECLARE_INTERFACE(Interface,"interface /1.0.0")
#endif // INTERFACE_H
plugintest.h
#ifndef PLUGINTEST_H
#define PLUGINTEST_H
#include <QObject>
#include <QString>
#include<QtPlugin>
#include "Interface.h"
class PluginTest:public QObject,public Interface
{
Q_OBJECT
Q_INTERFACES(Interface)
public:
PluginTest();
QString name() const;
};
#endif // PLUGINTEST_H
plugintest.cpp
#include "plugintest.h"
PluginTest::PluginTest()
{
}
Q_EXPORT_PLUGIN2(PluginTest,PluginTest)
QString PluginTest::name() const
{
return "pluginTest";
}

Answer 1

The problem is this line:
Q_EXPORT_PLUGIN2(PluginTest,PluginTest)
This is a Qt 4 feature, so you would need to either remove it, or put behind a version checking macro as follows:
#if QT_VERSION < QT_VERSION_CHECK(5, 0, 0)
Q_EXPORT_PLUGIN2(PluginTest,PluginTest)
#endif
For completeness, it seems you do not specify the meta data for the plugin. You would need to add that either unconditionally or conditionally with a version checking macro if you wish to support both Qt 4 and Qt 5 as follows:
class PluginTest:public QObject,public Interface
{
Q_OBJECT
Q_INTERFACES(Interface)
#if QT_VERSION >= QT_VERSION_CHECK(5, 0, 0)
Q_PLUGIN_METADATA(IID "your-string-here" FILE "file-here-but-can-be-empty")
#endif
...
};
Also, note that you append the "plugin" CONFIG item twice in your project file.