-base_null.nit:28,2--13: Warning: expression is not null, since it is a `null`.
-base_null.nit:42,2--13: Warning: expression is not null, since it is a `null`.
+base_null.nit:28,2--5: Warning: expression is always `null`.
+base_null.nit:42,2--5: Warning: expression is always `null`.
false
false
true