alt/base_as_notnull_alt4.nit:41,6--19: Warning: expression is already not null, since it is a `A`.
alt/base_as_notnull_alt4.nit:42,6--20: Warning: expression is already not null, since it is a `A`.
alt/base_as_notnull_alt4.nit:43,6--19: Warning: expression is already not null, since it is a `B`.
alt/base_as_notnull_alt4.nit:52,6--19: Warning: expression is already not null, since it is a `B`.
alt/base_as_notnull_alt4.nit:54,6--21: Type error: expected B, got A