Add neg test

Author: liufengyun

tests/init/neg/i12544.scala

@@ -0,0 +1,19 @@
+enum Enum:
+  case Case
+  case Case2(x: Int)
+
+def g(b: Enum.B): Int = b.foo()
+
+object Enum:
+  object nested:
+    val a: Enum = Case
+
+  val b: Enum = f(nested.a)
+
+  def f(e: Enum): Enum = e
+
+  class B() { def foo() = n + 1 }
+  g(new B())                       // error
+  val n: Int = 10
+
+@main def main(): Unit = println(Enum.b)