NULL in void WbSolid::setSolidMerger()

[ShuffleWire]

as in #4055
is it expected that, in WbSolid.cpp, void WbSolid::setSolidMerger()
we do
mSolidMerger = NULL;
?
i think we should do
mSolidMerger.clear()

[omichel]

Both are exactly equivalent from a binary point of view, however mSolidMerger.clear() is better because it shows this is not a standard C++ pointer, but a QPointer, so this is more readable.

[ShuffleWire]

that's true, the doc state that, sorry...
https://doc.qt.io/qt-5/qpointer.html#operator-eq
I believe leave it like that will cause no harm, the QPointer is made for this kind of usage !