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  1. Qt
  2. QTBUG-119912

moc: Generated code calls the overloaded non-const getter for when accessing the property

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    • Icon: Bug Bug
    • Resolution: Unresolved
    • Icon: P2: Important P2: Important
    • None
    • dev
    • Build tools: moc
    • None

      The following code cases the call of int a() but not the int a() const as could expected.

      class MyClass {
    Q_OBJECT
    Q_PROPERTY(int a READ a)

    int a() const
    {
         qDebug() << "const";
         return m_a;
    }
    int &a()
    {
         qDebug() << "non-const";
         return m_a;
    }
private:
    int m_a  = 1;
};

      This happens because the reader code accesses the MyClass uses pointer to non-const data when reading values:

      if (_c == QMetaObject::ReadProperty) {
        auto *_t = reinterpret_cast<MyClass *>(_o);
        (void)_t;
        void *_v = _a[0];
        switch (_id) {
        case 0: *reinterpret_cast< int*>(_v) = _t->a(); break;
        default: break;
        }

      It would be nice to detect this situation and force calling const function instead, since mutable getters might lead to really expensive shared data detach.

        For Gerrit Dashboard: QTBUG-119912
        # Subject Branch Project Status CR V
        598155,9 WIP: moc: Prefer const getter whenever possible dev qt/qtbase Status: NEW -2 0

            fabiankosmale Fabian Kosmale
            semlanik Alexey Edelev
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              Created:
              Updated:

                There is 1 open Gerrit change