Provides check method to check that all top-level definitions in tree are variance correct. Does not recurse inside methods. The method should be invoked once for each Template.
Check that variances of type lambda correspond to their occurrences in its body. Note: this is achieved by a mechanism separate from checking class type parameters. Question: Can the two mechanisms be combined in one?
Check that variances of type lambda correspond to their occurrences in its body. Note: this is achieved by a mechanism separate from checking class type parameters. Question: Can the two mechanisms be combined in one?
