Add test for Tree | Context => Tree

Author: liufengyun

compiler/src/dotty/tools/dotc/core/Annotations.scala

@@ -86,7 +86,7 @@ object Annotations {
       myTree.asInstanceOf[Tree]
 
     override def isEvaluating: Boolean = myTree == null
-    override def isEvaluated: Boolean = myTree.isInstanceOf[Tree @unchecked]
+    override def isEvaluated: Boolean = myTree.isInstanceOf[Tree]
   }
 
   /** An annotation indicating the body of a right-hand side,
@@ -119,7 +119,7 @@ object Annotations {
       myTree.asInstanceOf[Tree]
 
     override def isEvaluating: Boolean = myTree == null
-    override def isEvaluated: Boolean = myTree.isInstanceOf[Tree @unchecked]
+    override def isEvaluated: Boolean = myTree.isInstanceOf[Tree]
   }
 
   object LazyBodyAnnotation {

tests/neg-custom-args/isInstanceOf/or-type-trees.scala

@@ -0,0 +1,13 @@
+trait Tree
+trait Context
+
+def foo(myTree: Tree | (Context => Tree)) =
+  println(myTree.isInstanceOf[Tree])
+  myTree match
+    case treeFn: (Context => Tree) =>  // error
+    case _ =>
+
+def bar(myTree: Tree | (Context => Tree)) =
+  myTree match
+    case treeFn: (_ => _) =>       // ok
+    case _ =>