Allow @Alpha on types

Author: odersky

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

@@ -446,16 +446,15 @@ object SymDenotations {
 
     /** The name given in an `@alpha` annotation if one is present, `name` otherwise */
     final def erasedName(implicit ctx: Context): Name =
-      if (isTerm)
-        getAnnotation(defn.AlphaAnnot) match {
-          case Some(ann) =>
-            ann.arguments match {
-              case Literal(Constant(str: String)) :: Nil => str.toTermName
-              case _ => name
-            }
-          case _ => name
-        }
-      else name
+      getAnnotation(defn.AlphaAnnot) match {
+        case Some(ann) =>
+          ann.arguments match {
+            case Literal(Constant(str: String)) :: Nil =>
+              if (isType) str.toTypeName else str.toTermName
+            case _ => name
+          }
+        case _ => name
+      }
 
     // ----- Tests -------------------------------------------------
 

tests/run/alpha/Test_2.java

@@ -4,7 +4,7 @@
 public class Test_2 {
 
   public static void main(String[] args) {
-    Alpha<String> a = new Beta();
+    Alpha<String> a = new Bar();
     assert a.foo() == 1;
     assert a.bar("a").equals("aa");
     Alpha<String> aa = a.append(a);

tests/run/alpha/alpha_1.scala

@@ -11,7 +11,7 @@ abstract class Alpha[T] {
 
 }
 
-class Beta extends Alpha[String] {
+@alpha("Bar") class | extends Alpha[String] {
 
   @alpha("bar") override def foo(x: String) = x ++ x