- An “escaping var” is a bound var whose binder is not part of
t. A bound var can be a bound region or a bound type.
- Collects all the late-bound regions at the innermost binding level into a hash set.
- Finds the max universe present
- This trait is implemented for every type that can be visited, providing the skeleton of the traversal.
- This trait is implemented for every visiting traversal. There is a visit method defined for every type of interest. Each such method has a default that recurses into the type’s fields in a non-custom fashion.