Fix rare double-free in QObject machinery

As exposed by tst_QObjectRace::destroyRace we would sometimes end up
with a double-free when destroying a QSlotObject in multi-threaded
scenarios. One free would be done in ~QObject as the receiver was being
destroyed while the other free was done when deleting a QMetaCallEvent
object after we realized it was not needed because the receiver was
destroyed.

Since we can be in a separate thread from the receiver we should lock
before referencing the connection object.

Amends b7d073e9905bf9812ba96cecdcf6871a95517d30.

Change-Id: Icb53862dc880ae9a4e5581a1a9ee693573f7d9c7
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

0 files changed, 0 insertions, 0 deletions