Fixing bug 277935: now parser throws syntax error on assignments to descendants like x..y = 1

js/rhino/src/org/mozilla/javascript/IRFactory.java

@@ -1239,6 +1239,7 @@ final class IRFactory
           }
           case Token.GET_REF: {
             Node ref = left.getFirstChild();
+            checkMutableReference(ref);
             return new Node(Token.SET_REF, ref, right);
           }
         }
@@ -1246,6 +1247,14 @@ final class IRFactory
         throw Kit.codeBug();
     }
 
+    private void checkMutableReference(Node n)
+    {
+        int memberTypeFlags = n.getIntProp(Node.MEMBER_TYPE_PROP, 0);
+        if ((memberTypeFlags & Node.DESCENDANTS_FLAG) != 0) {
+            parser.reportError("msg.bad.assign.left");
+        }
+    }
+
     Node createAssignment(int assignType, Node left, Node right)
     {
         left = makeReference(left);
@@ -1297,6 +1306,7 @@ final class IRFactory
           }
           case Token.GET_REF: {
             Node ref = left.getFirstChild();
+            checkMutableReference(ref);
             Node opLeft = new Node(Token.USE_STACK);
             Node op = new Node(assignOp, opLeft, right);
             return new Node(Token.SET_REF_OP, ref, op);