alt/base_as_notnull_alt4.nit:41,6: Warning: expression is not null, since it is a `A`.
alt/base_as_notnull_alt4.nit:42,6--7: Warning: expression is not null, since it is a `A`.
alt/base_as_notnull_alt4.nit:43,6: Warning: expression is not null, since it is a `B`.
alt/base_as_notnull_alt4.nit:52,6: Warning: expression is not null, since it is a `B`.
alt/base_as_notnull_alt4.nit:54,6--21: Type Error: expected `B`, got `A`.