8069265: ClassCastException when compiled with JDK 9b08+, JDK8 compiles OK

Alternate fix for 8015499 to eliminate extra checkcast (by working around a limitation in Types#asSuper) without the side effect that results in 8069265

Reviewed-by: mcimadamore, jjg

langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2015, 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
@@ -1931,6 +1931,11 @@ public class Types {
      * Return the (most specific) base type of t that starts with the
      * given symbol.  If none exists, return null.
      *
+     * Caveat Emptor: Since javac represents the class of all arrays with a singleton
+     * symbol Symtab.arrayClass, which by being a singleton cannot hold any discriminant,
+     * this method could yield surprising answers when invoked on arrays. For example when
+     * invoked with t being byte [] and sym being t.sym itself, asSuper would answer null.
+     *
      * @param t a type
      * @param sym a symbol
      */

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2015, 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
@@ -720,7 +720,7 @@ public class TransTypes extends TreeTranslator {
 
     public void visitParens(JCParens tree) {
         tree.expr = translate(tree.expr, pt);
-        tree.type = erasure(tree.type);
+        tree.type = erasure(tree.expr.type);
         result = tree;
     }
 
@@ -755,7 +755,7 @@ public class TransTypes extends TreeTranslator {
         tree.clazz = translate(tree.clazz, null);
         Type originalTarget = tree.type;
         tree.type = erasure(tree.type);
-        JCExpression newExpression = translate(tree.expr, erasure(tree.expr.type));
+        JCExpression newExpression = translate(tree.expr, tree.type);
         if (newExpression != tree.expr) {
             JCTypeCast typeCast = newExpression.hasTag(Tag.TYPECAST)
                 ? (JCTypeCast) newExpression

langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/Gen.java

@@ -2145,7 +2145,8 @@ public class Gen extends JCTree.Visitor {
         // For basic types, the coerce(...) in genExpr(...) will do
         // the conversion.
         if (!tree.clazz.type.isPrimitive() &&
-            types.asSuper(tree.expr.type, tree.clazz.type.tsym) == null) {
+           !types.isSameType(tree.expr.type, tree.clazz.type) &&
+           types.asSuper(tree.expr.type, tree.clazz.type.tsym) == null) {
             code.emitop2(checkcast, makeRef(tree.pos(), tree.clazz.type));
         }
     }

langtools/test/tools/javac/CheckNoClassCastException.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2015, 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.
+ *
+ * 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.
+ */
+
+/*
+ * @test
+ * @bug 8069265
+ * @summary ClassCastException when compiled with JDK 9b08+, JDK8 compiles OK.
+ * @run main CheckNoClassCastException
+ */
+import java.util.*;
+
+public class CheckNoClassCastException {
+    static String result = "";
+    public static void main(String[] args) {
+        ListFail.main(null);
+        MapFail.main(null);
+        if (!result.equals("ListFailDoneMapFailDone"))
+            throw new AssertionError("Incorrect result");
+    }
+}
+
+class ListFail {
+    static interface Foo {
+    }
+
+    public static void main(String[] args) {
+        List<Date> list = new ArrayList<>();
+        list.add(new Date());
+
+        List<Foo> cList = (List<Foo>) (List<?>) list;
+        Date date = (Date) cList.get(0);
+        CheckNoClassCastException.result += "ListFailDone";
+    }
+}
+
+
+class MapFail {
+    static interface Foo {
+    }
+
+    public static void main(String[] args) {
+        Map<String,Date> aMap = new HashMap<>();
+        aMap.put("test",new Date());
+
+        Map<String,Foo> m = (Map<String,Foo>) (Map<?,?>) aMap;
+        Date q = (Date) m.get("test");
+        CheckNoClassCastException.result += "MapFailDone";
+    }
+}

langtools/test/tools/javac/T7053059/DoubleCastTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2015, 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
@@ -47,6 +47,7 @@ public class DoubleCastTest {
             m1((byte[])m());
             m1((byte[])os[0]);
             m1((byte[])this.x);
+            m1((byte[])((byte []) (o = null)));
         }
     }