Add test cases for protected constructors in super call arguments

Author: bracevac

tests/neg/protected-constructors.scala

@@ -0,0 +1,17 @@
+class A protected (x: Int)
+
+// Protected constructor in super call arguments (transitive parent)
+class B(a: A) extends A(a.hashCode)
+class C extends B(new A(1)) // error
+
+// Protected constructor in own parent's arguments
+class D protected (x: Any)
+class E extends D(new D(1)) // error
+
+// Mixed visibility constructors
+class F protected (x: Int) {
+  def this() = this(0) // public secondary
+}
+class G(f: F) extends F(f.hashCode)
+class H extends G(new F())   // ok: public secondary in super args
+class J extends G(new F(1))  // error: protected primary in super args