-error_ref_attr.nit:20,16--18: Redef Error: Wrong static type. found Int, expected B.
+error_ref_attr.nit:20,15--17: Redef Error: expected `B` return type; got `Int`.
+error_ref_attr.nit:20,15--17: Redef Error: expected `B` type for parameter `a'; got `Int`.