--- a/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/codegen/AssignSymbols.java	Thu Dec 14 20:19:34 2017 +0800
+++ b/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/codegen/AssignSymbols.java	Thu Dec 14 13:42:59 2017 +0100
@@ -796,7 +796,7 @@
             args.add(strictFlagNode);
 
         } else {
-            return LiteralNode.newInstance(unaryNode, true);
+            throw new AssertionError("Unexpected delete with " + rhs.getClass().getName() + " expression");
         }
         return new RuntimeNode(unaryNode, request, args);
     }

--- a/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/codegen/Lower.java	Thu Dec 14 20:19:34 2017 +0800
+++ b/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/codegen/Lower.java	Thu Dec 14 13:42:59 2017 +0100
@@ -228,6 +228,16 @@
         return super.leaveIndexNode(indexNode);
     }
 
+    @Override
+    public Node leaveDELETE(final UnaryNode delete) {
+        final Expression expression = delete.getExpression();
+        if (expression instanceof IdentNode || expression instanceof BaseNode) {
+            return delete;
+        }
+        return new BinaryNode(Token.recast(delete.getToken(), TokenType.COMMARIGHT), expression,
+                LiteralNode.newInstance(delete.getToken(), delete.getFinish(), true));
+    }
+
     // If expression is a primitive literal that is not an array index and does return its string value. Else return null.
     private static String getConstantPropertyName(final Expression expression) {
         if (expression instanceof LiteralNode.PrimitiveLiteralNode) {

--- a/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/parser/Parser.java	Thu Dec 14 20:19:34 2017 +0800
+++ b/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/parser/Parser.java	Thu Dec 14 13:42:59 2017 +0100
@@ -4404,15 +4404,6 @@
         final long unaryToken = token;
 
         switch (type) {
-        case DELETE: {
-            next();
-            final Expression expr = unaryExpression();
-            if (expr instanceof BaseNode || expr instanceof IdentNode) {
-                return new UnaryNode(unaryToken, expr);
-            }
-            appendStatement(new ExpressionStatement(unaryLine, unaryToken, finish, expr));
-            return LiteralNode.newInstance(unaryToken, finish, true);
-        }
         case ADD:
         case SUB: {
             final TokenType opType = type;
@@ -4420,6 +4411,7 @@
             final Expression expr = unaryExpression();
             return new UnaryNode(Token.recast(unaryToken, (opType == TokenType.ADD) ? TokenType.POS : TokenType.NEG), expr);
         }
+        case DELETE:
         case VOID:
         case TYPEOF:
         case BIT_NOT:

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/nashorn/src/jdk/nashorn/api/tree/test/JDK_8193296_Test.java	Thu Dec 14 13:42:59 2017 +0100
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package jdk.nashorn.api.tree.test;
+
+import jdk.nashorn.api.tree.CompilationUnitTree;
+import jdk.nashorn.api.tree.ExpressionStatementTree;
+import jdk.nashorn.api.tree.FunctionCallTree;
+import jdk.nashorn.api.tree.Parser;
+import jdk.nashorn.api.tree.Tree;
+import jdk.nashorn.api.tree.UnaryTree;
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+/**
+ * @test
+ * @bug 8184723
+ * @summary Parser should not eagerly transform delete expressions
+ * @run testng jdk.nashorn.api.tree.test.JDK_8193296_Test
+ */
+public class JDK_8193296_Test {
+    @Test
+    public void test() {
+        Parser p = Parser.create();
+        CompilationUnitTree t = p.parse("test", "function x() { }; delete x();", System.out::println);
+        Assert.assertEquals(t.getSourceElements().size(), 2);
+        Tree delt = ((ExpressionStatementTree)t.getSourceElements().get(1)).getExpression();
+        Assert.assertTrue(delt instanceof UnaryTree, delt.getClass().getName());
+        UnaryTree del = (UnaryTree)delt;
+        Assert.assertEquals(del.getKind(), Tree.Kind.DELETE);
+        Assert.assertTrue(del.getExpression() instanceof FunctionCallTree, del.getExpression().getClass().getName());
+    }
+}