t6667b.scala:16: error: ambiguous implicit values:
 both value a in object Test of type => Test.Box
 and value b of type Test.Box
 match expected type Test.Box
      new Test()
      ^
t6667b.scala:19: error: ambiguous implicit values:
 both value a in object Test of type => Test.Box
 and value b of type Test.Box
 match expected type Test.Box
    new Test()
    ^
two errors found