// a.h
//////////////////////////////////////////////////////////////////////////////

#ifndef A_H
#define A_H

#include <QtGlobal>
#include <QObject>

#ifdef BUILD_A
#    define A_EXPORT Q_DECL_EXPORT
#else
#    define A_EXPORT Q_DECL_IMPORT
#endif // BUILD_A

class A_EXPORT A : public QObject
{
    Q_OBJECT
    Q_ENUMS(Foo)

public:
    enum Foo
    {
        Bar
    };

    void dummyFunction();
};

#endif // A_H

// b.h
//////////////////////////////////////////////////////////////////////////////

#ifndef B_H
#define B_H

#include <QtGlobal>
#include <QObject>
#include "a.h"

#ifdef BUILD_B
#    define B_EXPORT Q_DECL_EXPORT
#else
#    define B_EXPORT Q_DECL_IMPORT
#endif // BUILD_B

class B_EXPORT B : public QObject
{
    Q_OBJECT
    Q_PROPERTY(A::Foo foo READ foo) // <--------------- !!!

public:
    A::Foo foo() const;
};

#endif // B_H