t3453.scala:18: error: type mismatch;
 found   : A
 required: B
        new A
        ^
t3453.scala:36: error: type mismatch;
 found   : A
 required: B
        new A
        ^
t3453.scala:50: error: type mismatch;
 found   : A
 required: B
        new A
        ^
t3453.scala:64: error: type mismatch;
 found   : A
 required: B
        new A
        ^
four errors found