Reachability examples

1.Inheritance.scala

trait A {/* has a `def toString: String` inherited from scala.Any */}
class B extends A { override def toString = "B"}
class C extends A { override def toString = "C" /* is this dead code? */ }

def main(a: Array[String]): Unit = {

  def foo(a: A) = a.toString // does it call .toString on all the A’s?
  
  val b: B = new B;
  val c: C = new C;
  foo(b)
}

2.Inheritance.scala

trait A {/* has a `def toString: String` inherited from scala.Any */}
class B extends A { override def toString = "B" /* is this dead code? */}
class C extends B { override def toString = "C"}

def main(a: Array[String]): Unit = {

  def foo(a: A) = a.toString // does it call .toString on all the A’s?
  val b: B = new B;
  val c: C = new C;
  foo(c)
}

3.Inheritance.scala

trait A {/* has a `def toString: String` inherited from scala.Any */}
trait B extends A { override def toString = super.toString + "B" /* is this dead code? */}
trait C extends A { override def toString = super.toString + "C" /* is this dead code? */}

def main(a: Array[String]): Unit = {

  def foo(a: A) = a.toString // does it call .toString on all the A’s?
  val b: B = new B with C{};
  foo(b)
}

4.Inheritance.scala

trait A {/* has a `def toString: String` inherited from scala.Any */}
trait B extends A { override def toString = super[A].toString + "B" /* is this dead code? */} // triggers https://issues.scala-lang.org/browse/SI-9645
trait C extends A { override def toString = super.toString + "C" /* is this dead code? */}

def main(a: Array[String]): Unit = {

  def foo(a: A) = a.toString // does it call .toString on all the A’s?
  val b: B = new B with C{};
  foo(b)
}

5.AbstractTypeMembers.scala

trait A { type I; val s: I; def toString = s.toString}
class B extends A { type I = Int; val s = 0;}
class E { override def toString = ??? /* is this dead code? */}

def main(a: Array[String]): Unit = {

  def foo(a: A) = a.toString // does it call .toString on all the A’s?
  val b: B = new B;
  val e: E = new E;
  foo(b)
}

6.Inheritance+OuterClasses.scala

trait A {/* has a `def toString: String` inherited from scala.Any */}
class B {self => class Inner extends A {override def toString = self.toString}}
class C extends B{ override def toString = "B" /* is this dead code? */ }

def main(a: Array[String]): Unit = {

  def foo(a: A) = a.toString // does it call .toString on all the A’s?
  val c: B = new C;
  val inner = new (c.Inner)
  foo(inner)
}

7.Inheritance+OuterClasses+PartialApplication.scala

trait A { def toStringUnapplied: () => String}
class B {self => class Inner extends A {def toStringUnapplied = self.toString _ }}
class C extends B { override def toString = "B" /* is this dead code? */ }

def main(a: Array[String]): Unit = {

  def foo(a: A) = a.toStringUnapplied
  
  val c: B = new C;
  val inner = new (c.Inner)
  foo(inner)
}

8.Generics.scala

class A { def toString = "A"}
class B { def toString = "B"}

def main(a: Array[String]): Unit = {

  def foo[A](a: A) = a.toString
  
  val a: A = new A;
  val b: B = new B;
  foo(a)
}

9.Outer+Generics+Inheritance.scala

trait A
class B {self => class Inner extends A { override def toString = self.toString}}
class C[T](val f: T) extends B { override def toString = f.toString}

class E {override def toString = "E" /* is this dead code? */ }

def main(a: Array[String]): Unit = {

  def foo(a: A) = a.toString // does it call .toString on all the A’s?
  val e: E = new E
  val c: B = new C(1);
  val inner = new (c.Inner)
  foo(inner)
}

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