Polymorphic functions vs structural types

[Blaisorblade]

minimized code

The following code doesn't compile, but should:

package bug
import reflect.Selectable.reflectiveSelectable

object options2 {
  type Option[T] = {
    def isEmpty: Boolean
  }
  type None[T] = Option[T]
  //Succeeds:
  val none : () => Option[Nothing] = () => new {
    def isEmpty = true
  }
  //Fails. Note I'm not even using T!
  val mkNone0 : [T] => () => Option[Nothing] = [T] => () => new {
    def isEmpty = true
  }
  //Fails. That'd be real.
  val mkNone : [T] => () => Option[T] = [T] => () => new {
    def isEmpty = true
  }
}

expectation

Should compile.

actual

[error] -- [E007] Type Mismatch Error: /Users/pgiarrusso/git/Coq/silr-dot/code/Bug.scala:16:3
[error] 16 |  }
[error]    |   ^
[error]    |   Found:    Object with PolyFunction {...}
[error]    |   Required: PolyFunction{apply: [T](): bug.options2.Option[Nothing]}
[error] -- [E007] Type Mismatch Error: /Users/pgiarrusso/git/Coq/silr-dot/code/Bug.scala:20:3
[error] 20 |  }
[error]    |   ^
[error]    |   Found:    Object with PolyFunction {...}
[error]    |   Required: PolyFunction{apply: [T](): bug.options2.Option[T]}
[error] two errors found

With version 0.20.0-RC1.

[ckipp01]

The expectation of this is that it compiles:

//> using scala 3.3.1-RC1-bin-20230510-d6c643c-NIGHTLY

import reflect.Selectable.reflectiveSelectable

object options2 {
  type Option[T] = {
    def isEmpty: Boolean
  }
  type None[T] = Option[T]
  val none: () => Option[Nothing] = () =>
    new {
      def isEmpty = true
    }
  val mkNone0: [T] => () => Option[Nothing] = [T] =>
    () =>
      new {
        def isEmpty = true
    }
  val mkNone: [T] => () => Option[T] = [T] =>
    () =>
      new {
        def isEmpty = true
    }
}

This now does compile as expected, so I'll go ahead and close. Please report back or reopen if I'm misunderstanding something here.