[Interest] can the QRegExpEngine cache acces objects belonging to an unloaded library during global destruction?

[René J. V. Bertin]

One more question: I'm not locking the mutex before emptying the cache ATM, but 
I guess that ideally I should.

The mutex can now be moved into the EngineCache class itself, but if I protect 
the clear() operation with a lock, what would be the most efficient? Continue to 
use a QBasicMutex and keep track of the QThread owning the lock, or just use a 
recursive and apparently slower QMutex?

Taking this a step further: is it actually possible to get the aboutToQuit 
signal in the middle of an access to this cache, in particular an access by *the 
same thread*? No non-deadlocking lock would protect against that so what would 
be the most appropriate course of action?

R.