src/jdk.compiler/share/classes/com/sun/tools/javac/tree/TreeInfo.java

@@ -180,10 +180,45 @@
              default:
                  return false;
          }
      }
  
+     /** Check if the given tree is an explicit reference to the 'this' instance of the
+      *  class currently being compiled. This is true if tree is:
+      *  - An unqualified 'this' identifier
+      *  - A 'super' identifier qualified by a class name whose type is 'currentClass' or a supertype
+      *  - A 'this' identifier qualified by a class name whose type is 'currentClass' or a supertype
+      *    but also NOT an enclosing outer class of 'currentClass'.
+      */
+     public static boolean isExplicitThisReference(Types types, Type.ClassType currentClass, JCTree tree) {
+         switch (tree.getTag()) {
+             case PARENS:
+                 return isExplicitThisReference(types, currentClass, skipParens(tree));
+             case IDENT: {
+                 JCIdent ident = (JCIdent)tree;
+                 Names names = ident.name.table.names;
+                 return ident.name == names._this || ident.name == names._super;
+             }
+             case SELECT: {
+                 JCFieldAccess select = (JCFieldAccess)tree;
+                 Type selectedType = types.erasure(select.selected.type);
+                 if (!selectedType.hasTag(TypeTag.CLASS))
+                     return false;
+                 Symbol.ClassSymbol currentClassSym = (Symbol.ClassSymbol)((Type.ClassType)types.erasure(currentClass)).tsym;
+                 Symbol.ClassSymbol selectedClassSym = (Symbol.ClassSymbol)((Type.ClassType)selectedType).tsym;
+                 Names names = select.name.table.names;
+                 return currentClassSym.isSubClass(selectedClassSym, types) &&
+                         (select.name == names._super ||
+                         (select.name == names._this &&
+                             (currentClassSym == selectedClassSym ||
+                             !currentClassSym.isEnclosedBy(selectedClassSym))));
+             }
+             default:
+                 return false;
+         }
+     }
+ 
      /** Is this a call to super?
       */
      public static boolean isSuperCall(JCTree tree) {
          Name name = calledMethodName(tree);
          if (name != null) {