Multiple qRegisterMetaType<T>() result in Binary compatibility break.

JulienMaille

Hi everyone,
I'm getting headaches trying to expose a class to both ActiveX and QtScript.
In order to expose it to activeX, I use Qt macro QAXCLASS(MyClass) which will call :

#define QAXCLASS(Class)
factory = new QAxClass<Class>(typeLibID().toString(), appID().toString());
qRegisterMetaType<Class*>(#Class"*");
[snip]

Later in my dll handling the script, I will register the class qScriptRegisterMetaType<MyClass*>(eng, qObjectToScriptValue, qObjectFromScriptValue) which will call

template<typename T>
int qScriptRegisterMetaType(
    QScriptEngine *eng,
    QScriptValue (*toScriptValue)(QScriptEngine *, const T &t),
    void (*fromScriptValue)(const QScriptValue &, T &t),
    const QScriptValue &prototype = QScriptValue()
#ifndef qdoc
    , T * /* dummy */ = 0
#endif
)
{
    const int id = qRegisterMetaType<T>(); // make sure it's registered
[snip]

this will compile and link, but on execution I get a qFatal stating that:

QMetaType::registerType: Binary comaptibility break. Type flags for type 'MyClass*' [2258] don't match. Previously registered TypeFlags(0x104), now registering TypeFlags(0x10c)

Since all these codes are hidden in Qt macro, is there anything I can do?
Thanks in advance for your help

mrjj

Hi
Its not something with const ?
https://bugreports.qt.io/browse/QTBUG-47631

Seems to be the same TypeFlags values in the bug report but
im not aware if other qRegisterMetaType scenarios result in same
ID/values for TypeFlags.

JulienMaille

No I'm not trying to register const.
However the first registration happen in the main app (QAXCLASS macro) while the latter is called from a plugin.

mrjj

@JulienMaille
Hmm, searching Google that error also seen when plugin loaded another version
of Qt Dlls. ( than main app)
I assume this cant be the case ?

JulienMaille

Yes this can't be the case. (the funny part is it compiles fine with Qt4)

JulienMaille

I finally found the trick. Write my own macro that doesn't blindly call qRegisterMetaType

#define MYAXTYPE(Class) \
    factory = new MyAxType<Class>(typeLibID().toString(), appID().toString()); \
    if( !QMetaType::isRegistered(QMetaType::type(#Class"*")) ) \
        qRegisterMetaType<Class*>(#Class"*"); \
    keys = factory->featureList(); \
    for (it = keys.begin(); it != keys.end(); ++it) { \
        factoryKeys += *it; \
        factories.insert(*it, factory); \
        creatable.insert(*it, false); \
    }\