Finds places where you're calling non-const member functions on temporaries.
For example getList().first(), which would detach if the container is shared.
There can be some false-positives, for example someHash.values().first() because refcount is 1.
But constFirst() is a good default, so you should try to use it wherever you can, since it's not practical to inspect all code and figure out if the container is shared or not.