not found: value getClass

[matobet]

reproduction steps

using Scala (2.13.2),

class Howdy(c: Class[_]) {
  def this() = this(getClass)
}

problem

Fails to compile with

Error:(8, 21) not found: value getClass
  def this() = this(getClass)

The above class compiles successfully with Scala 2.12.7.

[joroKr21]

This is intentional: scala/scala#8541
The behaviour was quite surprising because getClass referred to Predef.getClass and not this.getClass.

[matobet]

@joroKr21 is there a workaround for my case? because attempting def this() = this(this.getClass) results in

Error:(8, 21) this can be used only in a class, object, or template
  def this() = this(this.getClass)

[Jasper-M]

def this() = this(classOf[Howdy])

[matobet]

Ok, so you are saying the 2.12.7 code was incorrect all way long. But why is it illegal to do this.getClass? I believe Java allows you to do this.

[matobet]

@Jasper-M actually howdy is an abstract base class that really wants to do something with the concrete Class[_] of its child... Thats why I need the polymorphic call to getClass here.

[Jasper-M]

I'm not really sure how your old code accomplished that since constructors are not inherited. Maybe your minimized code is now too small to clearly see what the use case was. Anyway it's probably better to ask the question on e.g. users.scala-lang.org.

[joroKr21]

I can't think of a workaround that would cover all use cases.
But the original code wasn't working as intended either.
Java has the same limitation: https://docs.oracle.com/javase/specs/jls/se8/html/jls-8.html#jls-8.8.7.1

An explicit constructor invocation statement in a constructor body may not refer to any instance variables or instance methods or inner classes declared in this class or any superclass, or use this or super in any expression; otherwise, a compile-time error occurs.

[Jasper-M]

You could consider

class Howdy(c: Option[Class[_]] = None) {
  val clazz = c.getOrElse(this.getClass)
}

[dwijnand]

I believe Java allows you to do this.

It doesn't:

$ cat C.java && javac C.java
class C {
  private final Class<?> cls;

  C(Class<?> cls) {
    this.cls = cls;
  }

  C() {
    this(getClass());
  }
}
C.java:9: error: cannot reference this before supertype constructor has been called
    this(getClass());
         ^
1 error

[matobet]

Indeed, the legacy code I'm now migrating to Scala 2.13 must have accidentally depended on the old 2.12 behavior where it invoked Predef.getClass and was thus incorrect. It turns out those ctor overloads were never used and subclasses always supplied their specific classOf[Child].

Thanks everyone for the quick reactions and answers! 👍