On 21/03/2018 14:40, Marc-André Lureau wrote:
> +/* A typecast, checking for the type of arguments */
> +/* QObject is at offset 0, for all QObject-derived types */
> +#define QOBJECT(x) QEMU_GENERIC(x, \
> + (QNull *, (QObject *) x), \
> + (const QNull *, (const QObject *) x), \
> + (QNum *, (QObject *) x), \
> + (const QNum *, (const QObject *) x), \
> + (QString *, (QObject *) x), \
> + (const QString *, (const QObject *) x), \
> + (QDict *, (QObject *) x), \
> + (const QDict *, (const QObject *) x), \
> + (QList *, (QObject *) x), \
> + (const QList *, (const QObject *) x), \
> + (QBool *, (QObject *) x), \
> + (const QBool *, (const QObject *) x), \
> + (QObject *, x), \
> + (const QObject *, x), \
> + qobject_unknown_type(x))
Why not just
QEMU_GENERIC(x,
(QObject *, x),
(const QObject *, x),
({ \
QEMU_BUILD_BUG_ON(offsetof(typeof(*x), base));
&(x)->base;
}))
That is just an extension of what was being done before, and it is
resilient against people putting a random "QObject base" in the middle
of a struct.
Paolo
