--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/code/TypeAnnotations.java	Thu Nov 29 18:57:18 2018 -0800
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/code/TypeAnnotations.java	Fri Nov 30 10:37:48 2018 +0530
@@ -169,9 +169,12 @@
 
     /**
      * Determine whether an annotation is a declaration annotation,
-     * a type annotation, or both.
+     * a type annotation, or both (or none, i.e a non-annotation masquerading as one).
      */
     public AnnotationType annotationTargetType(Attribute.Compound a, Symbol s) {
+        if (!a.type.tsym.isAnnotationType()) {
+            return AnnotationType.NONE;
+        }
         List<Attribute> targets = annotationTargets(a.type.tsym);
         return (targets == null) ?
                 AnnotationType.DECLARATION :
@@ -319,6 +322,8 @@
                         onlyTypeAnnos.append(ta);
                         break;
                     }
+                    case NONE: // Error signaled already, just drop the non-annotation.
+                        break;
                 }
             }