LambdaType

Is this type close enough to that type so that members with the two types would override each other?

This means:

• Either both types are polytypes with the same number of type parameters and their result types match after renaming corresponding type parameters
• Or both types are method types with =:=-equivalent(*) parameter types and matching result types after renaming corresponding parameter types if the method types are dependent.
• Or both types are =:=-equivalent
• Or neither type takes term or type parameters.

(*) when matching with a Java method, we also regard Any and Object as equivalent parameter types. (TODO)

This function will always use unsafe-nulls semamtics to check the types. This is because we are using a relaxed rule (ignoring Null types) to check overriding Java methods.

Widens TermRefs one level to their underlyingOrMethodic type.

• If this term type is a TermRef, returns this.underlyingOrMethodic.
• Otherwise, returns this.