If a container is moved by its move assignment operator, according to the standard all their iterators except the past-end iterators remain valid but refer to the new container. This patch introduces support for this case in the iterator checkers.
I do not immediately understand what is this useful for. At least tests don't look like they make use of these offset manipulations(?)
Without full understanding, i wonder: when we overwrite one container with another, why don't we just overwrite all symbols associated with it, instead of creating a mixture of old and new symbols?
Or maybe this is an accidental part of another patch, that has something to do with resizes?
One test failed after rebased to the current master branch. Depending on the internal implementation of the iterator and the move operation of the container it could happen that after moving a container the begin() or end() of the target of the move returns an already existing iterator position to the source of the move which is wrong. Therefore we must first check for begin() and end() and only then check for the existence of the iterator position of the return value of a function returning an iterator.
I do not see which lines exactly you commented but I suppose it is about not reassigning all iterator positions to the new container upon moving. According to [[ C++ Reference | en.cppreference.com/w/cpp/container/vector/operator%3D ]] the past-end iterators are not moved to the new container.
I think this patch is in good shape.
This was about the replaceSymbol() sub. You can traverse history using the History tab, or if there's still a greyed out comment you can push the |<< button on it to jump to the respective historical diff.
In any case, i think in current form replaceSymbol() is much easier to understand, but still deserves a short comment, maybe a small example, maybe a better name (the word "rebase" comes to mind).