The meaning of `this.field` in class body

Compiler version

Scala 2 and Scala 3 (master)

Minimized code

class B(val y: Int):
  println(this.y)
  foo()
  def foo() = println(this.y)

class C(override val y: Int) extends B(10)

@main
def Test = new C(20)

Output

10
20

Expectation

I would expect this.y to have the same semantics both in the class body and method body.

It’s up to discussion whether an unqualified y in class body and in method body should have the same semantics.

[smarter]

class C(override val y: Int) extends B(10)

Could we disallow overriding a class parameter unless the overridden val is passed to the supercall (as in B(y))?

[smarter]

without fear of capture in C

That can be accomplised by writing @constructorOnly y: Int (https://github.com/lampepfl/dotty/blob/main/library/src/scala/annotation/constructorOnly.scala)