6869075: regression: javac crashes when compiling compound string assignment with generics

Javac should not add syntehtic cast to the LHS of an assignment expression

Reviewed-by: jjg

langtools/src/share/classes/com/sun/tools/javac/comp/TransTypes.java

@@ -631,7 +631,7 @@ public class TransTypes extends TreeTranslator {
     }
 
     public void visitAssignop(JCAssignOp tree) {
-        tree.lhs = translate(tree.lhs, tree.operator.type.getParameterTypes().head);
+        tree.lhs = translate(tree.lhs, null);
         tree.rhs = translate(tree.rhs, tree.operator.type.getParameterTypes().tail.head);
         tree.type = erasure(tree.type);
         result = tree;

langtools/test/tools/javac/generics/T6869075.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2009 Sun Microsystems, Inc.  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.
+ *
+ * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * @test
+ * @bug     6869075
+ * @summary regression: javac crashes when compiling compound string assignment with generics
+ * @author mcimadamore
+ */
+
+public class T6869075 {
+
+    static class Foo<X> {
+        X x;
+        Foo (X x) {
+            this.x = x;
+        }
+    }
+
+    static void test1(Foo<String> foo) {
+        String start = foo.x;
+        equals(foo.x += "foo", start + "foo");
+    }
+
+    static void test2(Foo<String> foo) {
+        String start = foo.x;
+        equals((foo.x += "foo"), (start + "foo"));
+    }
+
+    static void test3(Foo<String> foo) {
+        String start = foo.x;
+        equals(((foo.x += "foo")), ((start + "foo")));
+    }
+
+    public static void main(String[] args) {
+        test1(new Foo<String>("Hello!"));
+        test2(new Foo<String>("Hello!"));
+        test3(new Foo<String>("Hello!"));
+    }
+
+    static void equals(String found, String req) {
+        if (!found.equals(req)) {
+            throw new AssertionError("Error (expected: "+ req +
+                                     " - found: " + found + ")");
+        }
+    }
+}