pass.Report(diag)
	})
	return nil, nil
}

func structuralTypes(t types.Type) ([]types.Type, error) {
	var structuralTypes []types.Type
	if tp, ok := aliases.Unalias(t).(*types.TypeParam); ok {
		terms, err := typeparams.StructuralTerms(tp)
		if err != nil {
			return nil, err
		}
		for _, term := range terms {
			structuralTypes = append(structuralTypes, term.Type())
		}
	} else {