The usable stubs extended help doesn't do this.type

[som-snytt]

The usable stubs extended help doesn't do this.type.

scala 2.13.0-M5> trait T { def f: this.type }
defined trait T

scala 2.13.0-M5> class C extends T
                       ^
                 error: class C needs to be abstract, since method f in trait T of type => C.this.type is not defined

scala 2.13.0-M5> trait T { def f: this.type ; def g: Int ; def h: String }
defined trait T

scala 2.13.0-M5> class C extends T
                       ^
                 error: class C needs to be abstract, since:
                 it has 3 unimplemented members.
                 /** As seen from class C, the missing signatures are as follows.
                  *  For convenience, these are usable as stub implementations.
                  */
                   def f: C = ???
                   def g: Int = ???
                   def h: String = ???

[som-snytt]

Woo-hoo @hrhino why is it hrhino and not woohoono? See linked ticket.

Welcome to Scala 2.13.4 (OpenJDK 64-Bit Server VM, Java 15).
Type in expressions for evaluation. Or try :help.

scala> trait T { def f: this.type }
trait T

scala> class C extends T
             ^
       error: class C needs to be abstract. Missing implementation for:
         def f: C.this.type // inherited from trait T