Fix scala#5006

Author: Blaisorblade

compiler/src/dotty/tools/dotc/transform/TypeTestsCasts.scala

@@ -140,7 +140,15 @@ object TypeTestsCasts {
   }
 
   def interceptTypeApply(tree: TypeApply)(implicit ctx: Context): Tree = trace(s"transforming ${tree.show}", show = true) {
-    tree.fun match {
+    interceptTypeApply1(tree, tree.fun match {
+      case i: Ident =>
+        desugarIdent(i).withPos(tree.fun)
+      case t => t
+    })
+  }
+
+  private def interceptTypeApply1(tree: TypeApply, treeFun: Tree)(implicit ctx: Context): Tree = {
+    treeFun match {
       case fun @ Select(expr, selector) =>
         val sym = tree.symbol
 

tests/neg/i5006.scala

@@ -0,0 +1,7 @@
+object i0 {
+  // Adding anything in front of asInstanceOf,
+  // i0 or this, makes the error go away.
+  def i1: Int = asInstanceOf[Int].toInt
+
+  val i2 = asInstanceOf[Int]
+}