While QMessageAuthenticationCode is not copyable, result() is
nevertheless const, so a user could prepare a
QMessageAuthenticationCode object with setKey() and addData(), pass it
by const reference to two threads, which each just call result() on
it. This should be safe, but because result() performed lazy
evaluation without being internally synchronized, this would cause
data races.
Fix in the same was as b904de43a5 did
for QCryptographicHash. See there for a detailed discussion of the
solution.
Fixes: QTBUG-111347
Pick-to: 6.5 6.4 6.2 5.15
Change-Id: I1feb380973c480ad6268349a0a46ac471b9ca0f7
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: David Faure <david.faure@kdab.com>
2449af142f